ErisFUgq

1junk basket
21.n. [Drilling]
3A tool run into the wellbore to retrieve junk from the bottom of the hole.
4junk
5junk sub
6basket sub
7--
8junk basket
92.n. [Drilling]
10A large, rectangular steel box, usually with sides made of expanded metal to facilitate seeing what is inside. The junk basket is used by the rig crew to store an assortment of relatively small parts of the drilling rig, ranging from drill bits to crossover subs to lifting subs to spare kellys. Dimensions vary, but a typical junk basket on a land rig is 8 ft wide [2.5 m] by 3 ft [1 m] deep by 30 ft [9 m] long.
11junk, kelly, sub
12None
13None
14--
15jackup
161.n. [Drilling]
17A self-contained combination drilling rig and floating barge, fitted with long support legs that can be raised or lowered independently of each other. The jackup, as it is known informally, is towed onto location with its legs up and the barge section floating on the water. Upon arrival at the drilling location, the legs are jacked down onto the seafloor, preloaded to securely drive them into the seabottom, and then all three legs are jacked further down. Since the legs have been preloaded and will not penetrate the seafloor further, this jacking down of the legs has the effect of raising the jacking mechanism, which is attached to the barge and drilling package. In this manner, the entire barge and drilling structure are slowly raised above the water to a predetermined height above the water, so that wave, tidal and current loading acts only on the relatively small legs and not the bulky barge and drilling package.
18bridge, mobile offshore drilling unit, Texas deck
19None
20None
21--
22jet cutter
231.n. [Well Workover and Intervention]
24A downhole tool, generally run on wireline or coiled tubing, that uses the detonation of a shaped explosive charge to cut the surrounding tubing or casing wall. The cutting action leaves a relatively clean cut surface, although the explosive action tends to flare the cut ends, making retrieval of cut tubular difficult if the fishing tool engages on the external surfaces.
25None
26None
27None
28--
29joint
301.n. [Geology]
31A surface of breakage, cracking or separation within a rock along which there has been no movement parallel to the defining plane. The usage by some authors can be more specific: When walls of a fracture have moved only normal to each other, the fracture is called a joint.
32fault, fracture
33None
34None
35--
36joint
372.n. [Drilling]
38A length of pipe, usually referring to drillpipe, casing or tubing. While there are different standard lengths, the most common drillpipe joint length is around 30 ft [9 m]. For casing, the most common length of a joint is 40 ft [12 m].
39casing, casing string, connection, drillpipe, kelly down, make a connection
40None
41None
42--
43junk sub
441.n. [Well Workover and Intervention]
45A downhole tool with a profiled external surface designed to catch and retrieve junk or debris from the wellbore. The debris is carried up the tool-string annulus in the circulation fluid. An indented profile creating a larger annular area causes the fluid flow rate to drop and allows debris to drop into a basket or receptacle located at the base of the tool.
46None
47junk basket
48None
49--
50jackup rig
511.n. [Drilling]
52A self-contained combination drilling rig and floating barge, fitted with long support legs that can be raised or lowered independently of each other. The jackup, as it is known informally, is towed onto location with its legs up and the barge section floating on the water. Upon arrival at the drilling location, the legs are jacked down onto the seafloor, preloaded to securely drive them into the seabottom, and then all three legs are jacked further down. Since the legs have been preloaded and will not penetrate the seafloor further, this jacking down of the legs has the effect of raising the jacking mechanism, which is attached to the barge and drilling package. In this manner, the entire barge and drilling structure are slowly raised above the water to a predetermined height above the water, so that wave, tidal and current loading acts only on the relatively small legs and not the bulky barge and drilling package.
53bridge, mobile offshore drilling unit, Texas deck
54None
55None
56--
57kaolinite
581.n. [Geology]
59[Al4Si4O10(OH)8]A type of clay mineral from the kaolin group that forms through the weathering of feldspar and mica group minerals. Unlike some clay minerals like montmorillonite, kaolinite is not prone to shrinking or swelling with changes in water content.
60clay, feldspar, mica, weathering
61None
62None
63--
64kaolinite
652.n. [Drilling Fluids]
66A common two-layer clay that does not swell when exposed to water. Kaolinite is used to make paper, pottery and bricks. It occurs naturally in shale and claystone, and therefore is a common component of drill solids in muds.
67clay, clay-water interaction, methylene blue test
68None
69None
70--
71kerogen
721.n. [Geology, Geochemistry, Shale Gas]
73The naturally occurring, solid, insoluble organic matter that occurs in source rocks and can yield oil upon heating. Kerogen is the portion of naturally occurring organic matter that is nonextractable using organic solvents. Typical organic constituents of kerogen are algae and woody plant material. Kerogens have a high molecular weight relative to bitumen, or soluble organic matter. Bitumen forms from kerogen during petroleum generation. Kerogens are described as Type I, consisting of mainly algal and amorphous (but presumably algal) kerogen and highly likely to generate oil; Type II, mixed terrestrial and marine source material that can generate waxy oil; and Type III, woody terrestrial source material that typically generates gas.
74gas-prone, geochemistry, hydrocarbon, oil-prone, petroleum system, source rock, vitrinite, vitrinite reflectance
75None
76None
77--
78kickoff
791.n. [Drilling]
80The point at which a vertical well is intentionally deviated.
81None
82None
83None
84--
85kilogram per cubic meter
861.n. [Drilling Fluids]
87The SI unit of measurement for density. Mud weights are typically expressed in kg/m3. The conversion factor from lbm/gal to kg/m3 is 120. For example, 12 lbm/gal = 1440 kg/m3.
88mud weight
89None
90None
91--
92kb
931.n. [Drilling]
94An adapter that serves to connect the rotary table to the kelly. The kelly bushing has an inside diameter profile that matches that of the kelly, usually square or hexagonal. It is connected to the rotary table by four large steel pins that fit into mating holes in the rotary table. The rotary motion from the rotary table is transmitted to the bushing through the pins, and then to the kelly itself through the square or hexagonal flat surfaces between the kelly and the kelly bushing. The kelly then turns the entire drillstring because it is screwed into the top of the drillstring itself. Depth measurements are commonly referenced to the KB, such as 8327 ft KB, meaning 8327 feet below the kelly bushing.
95None
96kelly bushing, rotary bushing
97None
98--
99key stop
1001.n. [Production]
101A method of restricting the travel of a ball valve from fully open to fully closed. The stem key bears against the ends of an arc machined in the adapter plate.
102None
103None
104None
105--
106kill
1071.vb. [Drilling]
108To stop a well from flowing or having the ability to flow into the wellbore. Kill procedures typically involve circulating reservoir fluids out of the wellbore or pumping higher density mud into the wellbore, or both. In the case of an induced kick, where the mud density is sufficient to kill the well but the reservoir has flowed as a result of pipe movement, the driller must circulate the influx out of the wellbore. In the case of an underbalanced kick, the driller must circulate the influx out and increase the density of the drilling fluid. In the case of a producing well, a kill fluid with sufficient density to overcome production of formation fluid is pumped into the well to stop the flow of reservoir fluids.
109drillstem test, kick, mud, mud density, shear ram, snubbing, underbalanced, underground blowout
110density
111None
112--
113kinetic effect
1141.n. [Production Logging]
115In a gradiomanometer tool, the pressure difference observed when the fluid velocity opposite the upper pressure sensor differs from that across the lower pressure sensor. This difference usually occurs opposite points of fluid entry or exit, and at sudden changes in diameter, such as at the tubing shoe. The result is a sharp deflection on the log that may be misinterpreted as a local change in fluid density.
116fluid-density log, friction effect, holdup log
117None
118None
119--
120kelly
1211.n. [Drilling]
122A long square or hexagonal steel bar with a hole drilled through the middle for a fluid path. The kelly is used to transmit rotary motion from the rotary table or kelly bushing to the drillstring, while allowing the drillstring to be lowered or raised during rotation. The kelly goes through the kelly bushing, which is driven by the rotary table. The kelly bushing has an inside profile matching the kelly's outside profile (either square or hexagonal), but with slightly larger dimensions so that the kelly can freely move up and down inside.
123circulation system, hook, junk basket, kelly bushing, kelly hose, kelly spinner, make a connection, mousehole, rathole, rotary bushing, rotary table, saver sub, slips, topdrive
124None
125None
126--
127keyseat
1281.n. [Drilling]
129A small-diameter channel worn into the side of a larger diameter wellbore. This can be the result of a sharp change in direction of the wellbore (a dogleg), or if a hard formation ledge is left between softer formations that enlarge over time. In either case, the diameter of the channel is typically similar to the diameter of the drillpipe. When larger diameter drilling tools such as tool joints, drill collars, stabilizers, and bits are pulled into the channel, their larger diameters will not pass and the larger diameter tools may become stuck in the keyseat. Preventive measures include keeping any turns in the wellbore gradual and smooth. The remedy to keyseating involves enlarging the worn channel so that the larger diameter tools will fit through it.
130dogleg, drill collar, mechanical sticking, tool joint
131None
132None
133--
134kill line
1351.n. [Drilling]
136A high-pressure pipe leading from an outlet on the BOP stack to the high-pressure rig pumps. During normal well control operations, kill fluid is pumped through the drillstring and annular fluid is taken out of the well through the choke line to the choke, which drops the fluid pressure to atmospheric pressure. If the drillpipe is inaccessible, it may be necessary to pump heavy drilling fluid in the top of the well, wait for the fluid to fall under the force of gravity, and then remove fluid from the annulus. In such an operation, while one high pressure line would suffice, it is more convenient to have two. In addition, this provides a measure of redundancy for the operation. In floating offshore operations, the choke and kill lines exit the subsea BOP stack and run along the outside of the riser to the surface. The volumetric and frictional effects of these long choke and kill lines must be taken into account to properly control the well.
137blowout preventer, BOP stack, choke line, well control
138None
139None
140--
141kirchhoff equation
1421.n. [Geophysics]
143A mathematical representation of the principle that a wavefield at a given point in space and time can be considered as the superposition of waves propagating from adjacent points and earlier times. It is an integral form of the wave equation in which the wave function at a point is represented as the sum (integral) of contributions from a surface enclosing the given point. The Kirchhoff equation (also called the Kirchhoff integral) is the basis for Kirchhoff migration.
144Kirchhoff migration, wave equation
145None
146None
147--
148kelly bushing
1491.n. [Drilling]
150An adapter that serves to connect the rotary table to the kelly. The kelly bushing has an inside diameter profile that matches that of the kelly, usually square or hexagonal. It is connected to the rotary table by four large steel pins that fit into mating holes in the rotary table. The rotary motion from the rotary table is transmitted to the bushing through the pins, and then to the kelly itself through the square or hexagonal flat surfaces between the kelly and the kelly bushing. The kelly then turns the entire drillstring because it is screwed into the top of the drillstring itself. Depth measurements are commonly referenced to the KB, such as 8327 ft KB, meaning 8327 feet below the kelly bushing.
151kelly, rotary table
152rotary bushing
153KB
154--
155kh
1561.n. [Well Testing]
157The product of formation permeability, k, and producing formation thickness, h, in a producing well, referred to as kh. This product is the primary finding of buildup and drawdown tests and is a key factor in the flow potential of a well. It is used for a large number of reservoir engineering calculations such as prediction of future performance, secondary and tertiary recovery potential, and potential success of well-stimulation procedures. Obtaining the best possible value of this product is the primary objective of transient well tests. To separate the elements of the product, it is necessary to have some independent measurement of one of them, usually the estimation of producing formation thickness from well logs. Permeability is then calculated, provided that the fluid formation volume factor and viscosity are known. The accuracy of the calculated permeability is entirely dependent on the accuracy of the estimated formation thickness and the fluid properties.
158permeability thickness
159None
160None
161--
162kill weight fluid
1631.n. [Drilling Fluids]
164A mud whose density is high enough to produce a hydrostatic pressure at the point of influx in a wellbore and shut off flow into the well. Kill-weight mud, when needed, must be available quickly to avoid loss of control of the well or a blowout. Thus, it is usually made by weighting up some of the mud in the system or in storage by adding barite or hematite. Unless diluted in advance, the mud may become too thick and perhaps un-pumpable due to high solids loading. A weight-up pilot test can identify if and how much dilution will be needed in advance of adding weighting material to the mud in the pits.
165None
166None
167kill-weight fluid
168--
169kirchhoff migration
1701.n. [Geophysics]
171A method of seismic migration that uses the integral form (Kirchhoff equation) of the wave equation. All methods of seismic migration involve the backpropagation (or continuation) of the seismic wavefield from the region where it was measured (Earth's surface or along a borehole) into the region to be imaged. In Kirchhoff migration, this is done by using the Kirchhoff integral representation of a field at a given point as a (weighted) superposition of waves propagating from adjacent points and times. Continuation of the wavefield requires a background model of seismic velocity, which is usually a model of constant or smoothly varying velocity. Because of the integral form of Kirchhoff migration, its implementation reduces to stacking the data along curves that trace the arrival time of energy scattered by image points in the earth.
172diffraction, Kirchhoff equation, migration, ray tracing
173diffraction stack
174None
175--
176kelly down
1771.adj. [Drilling]
178Referring to the condition that occurs when the kelly is all the way down, so drilling progress cannot continue. A connection must be made, which has the effect of raising the kelly up by the length of the new joint of drillpipe added, so drilling can resume.
179joint
180None
181None
182--
183kick
1841.n. [Drilling]
185A flow of formation fluids into the wellbore during drilling operations. The kick is physically caused by the pressure in the wellbore being less than that of the formation fluids, thus causing flow. This condition of lower wellbore pressure than the formation is caused in two ways. First, if the mud weight is too low, then the hydrostatic pressure exerted on the formation by the fluid column may be insufficient to hold the formation fluid in the formation. This can happen if the mud density is suddenly lightened or is not to specification to begin with, or if a drilled formation has a higher pressure than anticipated. This type of kick might be called an underbalanced kick. The second way a kick can occur is if dynamic and transient fluid pressure effects, usually due to motion of the drillstring or casing, effectively lower the pressure in the wellbore below that of the formation. This second kick type could be called an induced kick.
186choke line, differential pressure, hydrostatic pressure, kill, mud density, mud weight, pressure hunt, ram blowout preventer, snubbing, swab, wildcat
187None
188None
189--
190kick
1912.vb. [Drilling]
192To flow formation fluids into the wellbore in an unplanned fashion, as in "the well kicked during the trip."
193None
194None
195None
196--
197kill weight fluid
1981.n. [Drilling Fluids]
199A mud with density high enough to produce a hydrostatic pressure at the point of influx in a wellbore that is sufficient to shut off flow into the well. Kill-weight mud, when needed, must be available quickly to avoid loss of control of the well or a blowout. Thus, it is usually made by weighting up some of the mud (link to ID 2107) in the system or in storage by adding barite or hematite. Unless diluted in advance, the mud may become too thick and perhaps un-pumpable due to high solids loading. A weight-up pilot test can identify if and how much dilution will be needed in advance of adding weighting material to the mud in the pits.
200barite, deflocculant, hydrostatic pressure, mud weight, pilot test, rheology
201None
202kill-weight mud
203--
204koch curve
2051.n. [Reservoir Characterization]
206A curve used to generate a certain type of fractal geometry. Straight lines are replaced by regular polygons repeatedly. These curves look like a snowflake when displayed graphically and are used to illustrate that a curve has a fractal dimension D>1.
207fractal, Sierpinski gasket
208None
209None
210--
211kelly spinner
2121.n. [Drilling]
213A mechanical device for rotating the kelly. The kelly spinner is typically pneumatic. It is a relatively low torque device, useful only for the initial makeup of threaded tool joints. It is not strong enough for proper torque of the tool joint or for rotating the drillstring itself. The kelly spinner has largely replaced the infamous spinning chains, which were responsible for numerous injuries on the rig floor.
214kelly, spinning chain, tool joint
215None
216None
217--
218kick off
2191.vb. [Drilling]
220Intentionally deviate a vertical well.
221None
222None
223None
224--
225kill weight mud
2261.n. [Drilling Fluids]
227Amudwith density high enough to produce a hydrostaticpressureat the point of influx in a wellbore that is sufficient to shut off flow into the well.Kill-weight mud, when needed, must be available quickly to avoid loss of control of the well or ablowout. Thus, it is usually made by weighting up some of the mud (link to ID 2107) inthe system or in storage by adding barite orhematite. Unless diluted in advance, the mud may become too thick and perhaps un-pumpable due to high solids loading. A weight-up pilot test can identify if and how muchdilutionwill be needed in advance of addingweighting materialto the mud in the pits.
228barite, deflocculant, hydrostatic pressure, mud weight, pilot test, rheology
229None
230None
231--
232lame constant
2331.n. [Geophysics]
234One of two elastic constants named for French mathematician Gabriel Lamé (1795 to 1870). The first Lamé constant is λ, the bulk modulus (K) less two-thirds of the shear modulus (μ):λ = K − (2/3)μThe second Lamé constant is the shear modulus (μ):μ = τ / γ = (ΔF/A) / (ΔL/L),whereμ = Shear modulusτ = Shear stress = ΔF/AΔF = Increment of shear forceA = Area acted on by the shear forceγ = Shear strain = ΔL/LΔL = Increment of transverse displacement parallel to AL = Original length.Lamé constants derived from elastic-wave velocities:λ = ρ(VP2 − 2VS2)μ = ρVS2λ/μ = (VP/VS)2 − 2,whereλ = Lamé's first constantμ = Lamé's second constant, the shear modulusVP = Compressional-wave (P-wave) velocityVS = Shear-wave (S-wave) velocityρ = Density.
235bulk modulus, elastic constants, shear modulus, P-wave, S-wave
236None
237None
238--
239levelwind
2401.n. [Well Workover and Intervention]
241The assembly on a coiled tubing reel that guides the tubing string onto the drum. Accurate spooling is necessary to avoid damaging the tubing and to ensure that the entire string can be run and retrieved without jamming. The levelwind functions automatically, although it incorporates a manual override to facilitate minor corrections.
242coiled tubing
243None
244None
245--
246lithification
2471.n. [Geology]
248The process by which unconsolidated sediments become sedimentary rock. Sediments typically are derived from preexisting rocks by weathering, transported and redeposited, and then buried and compacted by overlying sediments. Cementation causes the sediments to harden, or lithify, into rock.
249cement, compaction, consolidated, detrital, diagenesis, hiatus, primary porosity, sediment, tuff
250None
251None
252--
253lost returns
2541.n. [Drilling]
255The reduced or total absence of fluid flow up the annulus when fluid is pumped through the drillstring. Though the definitions of different operators vary, this reduction of flow may generally be classified as seepage (less than 20 bbl/hr [3 m3/hr]), partial lost returns (greater than 20 bbl/hr [3 m3/hr] but still some returns), and total lost returns (where no fluid comes out of the annulus). In this severe latter case, the hole may not remain full of fluid even if the pumps are turned off. If the hole does not remain full of fluid, the vertical height of the fluid column is reduced and the pressure exerted on the open formations is reduced. This in turn can result in another zone flowing into the wellbore, while the loss zone is taking mud, or even a catastrophic loss of well control. Even in the two less severe forms, the loss of fluid to the formation represents a financial loss that must be dealt with, and the impact of which is directly tied to the per barrel cost of the drilling fluid and the loss rate over time.
256lost circulation
257None
258None
259--
260lost returns
2612.n. [Drilling Fluids]
262Another term for lost circulation, a lack of mud returning to the surface after being pumped down a well. Lost circulation occurs when the drill bit encounters natural fissures, fractures or caverns, and mud flows into the newly available space. Lost circulation may also be caused by applying more mud pressure (that is, drilling overbalanced) on the formation than it is strong enough to withstand, thereby opening up a fracture into which mud flows.
263bridging material, circulation loss, fiber lost-circulation material, flake lost-circulation material, granular lost-circulation material, gunk plug, gunk squeeze, hydrostatic pressure, lost-circulation material, mud weight, pill, shear strength, shear-strength measurement test
264lost circulation
265None
266--
267laminar flow
2681.n. [Production Logging]
269A type of streamlined flow for single-phase fluids in which the fluid moves in parallel layers, or laminae. The layers flow smoothly over each other with instabilities being dampened by the viscosity. Laminar flow occurs in straight pipes when the Reynolds number is below a critical value, corresponding to a low production rate. Above this value, the flow is turbulent. For laminar flow in straight pipes, the velocity profile across the pipe is parabolic, increasing from zero at the wall of the pipe to a maximum at the center equal to twice the mean velocity.
270flow regime
271None
272None
273--
274laminar flow
2752.n. [Production]
276The flow of a viscous fluid in which the fluid moves in parallel layers with a fixed velocity gradient from the centerline to the containing walls of the conduit. Sometimes referred to as streamline flow. It occurs at a low Reynolds number, a dimensionless term related to fluid viscosity and flow rates.
277None
278None
279None
280--
281lgs
2821.n. [Drilling Fluids]
283A type of drilling-fluid solid having a lower density than the barite or hematite that is used to weight up a drilling fluid, including drill solids plus the added bentonite clay. The mud engineer calculates the concentration of these and other types of solids on the basis of mud weight, retort analysis, chloride titrations and other information. Solids are reported as lbm/bbl or vol.%. Water is 1.0, barite 4.20, and hematite 5.505 g/cm3. Low-gravity solids are normally assumed to have a density of 2.60 g/cm3..
284material-balance equation, mud report, suspended solids
285None
286None
287--
288lithostatic pressure
2891.n. [Geology]
290The pressure of the weight of overburden, or overlying rock, on a formation; also called geostatic pressure.
291absolute pressure, formation pressure, normal pressure, overburden, pressure gradient, reservoir pressure, virgin pressure
292None
293geostatic pressure
294--
295lot
2961.n. [Drilling]
297Abbreviation for leakoff test, a test to determine the strength or fracture pressure of the open formation, usually conducted immediately after drilling below a new casing shoe. During the test, the well is shut in and fluid is pumped into the wellbore to gradually increase the pressure that the formation experiences. At some pressure, fluid will enter the formation, or leak off, either moving through permeable paths in the rock or by creating a space by fracturing the rock. The results of the leakoff test dictate the maximum pressure or mud weight that may be applied to the well during drilling operations. To maintain a small safety factor to permit safe well control operations, the maximum operating pressure is usually slightly below the leakoff test result.
298casing shoe, formation fracture pressure, fracture gradient, leakoff, mud weight
299pressure integrity test
300leakoff test
301--
302laminated sand
3031.n. [Formation Evaluation]
304A particular model, or equation, for deriving the water saturation from resistivity and other logs. The model assumes a laminar shale distribution and considers the total resistivity to be the sum in parallel of the sand and shale laminae.
305Archie equation, saturation equation
306None
307None
308--
309licensing round
3101.n. [Oil and Gas Business]
311An occasion when a governmental body offers exploration acreage for leasing by exploration and production companies, typically in return for a fee and a performance or work obligation, such as acquisition of seismic data or drilling a well. Exploration licenses are initially of limited duration (about 5 years) after which there might be a requirement to return half or more of the licensed acreage to the state. If hydrocarbons are discovered, a separate production license or production-sharing agreement is usually drawn up before development can proceed.
312development, exploration, hydrocarbon, lease, production
313None
314None
315--
316littoral
3171.adj. [Geology]
318Pertaining to an environment of deposition affected by tides, the area between high tide and low tide. Given the variation of tides and land forms from place to place, geologists describe littoral zones locally according to the fauna capable of surviving periodic exposure and submersion.
319abyssal, bathyal, benthic, depositional environment, neritic
320None
321None
322--
323love wave
3241.n. [Geophysics]
325A type of surface wave in which particles oscillate horizontally and perpendicularly to the direction of wave propagation.
326wave
327Q wave
328None
329--
330lamination
3311.n. [Geology]
332A fine layer (~ 1 mm thick) in strata, also called a lamina, common in fine-grained sedimentary rocks such as shale, siltstone and fine sandstone. A sedimentary bed comprises multiple laminations, or laminae.
333stratum, turbidite, turbidity current
334None
335None
336--
337life of the well
3381.n. [Well Completions]
339The period of time during which economically sustainable production levels may be expected from a well. The anticipated well life and the characteristics of the reservoir fluid are the two main factors in specifying the completion system components.
340None
341None
342None
343--
344live cement
3451.n. [Well Workover and Intervention]
346A term used to describe a cement slurry that remains liquid but is still capable of thickening or setting to become an unmovable solid mass. Some remedial operations treat the excess live cement slurry with a contaminant to extend the thickening time and allow its safe removal from the wellbore.
347thickening time
348None
349None
350--
351low colloid oil mud
3521.n. [Drilling Fluids]
353An oil mud designed and maintained with a minimum of colloid-sized solids, typically by omitting fatty-acid soap and lime, and minimizing organophilic clays and fluid-loss additives. Low-colloid oil mud, also called a relaxed filtrate oil mud, increases drilling rate. A disadvantage is that filter cake formed on sands is not tight, can quickly become very thick, and can cause pipe to stick by differential pressure.
354differential pressure sticking, filtration, gilsonite, oil-mud emulsifier, organophilic clay
355relaxed filtrate oil mud
356None
357--
358landing collar
3591.n. [Well Completions]
360A component installed near the bottom of the casing string on which the cement plugs land during the primary cementing operation. The internal components of the landing collar are generally fabricated from plastics, cement and other drillable materials.
361casing string, cement plug, float collar, primary cementing
362None
363None
364--
365lifting sub
3661.n. [Well Completions]
367A short drillstring component that is temporarily connected to the top of a tool assembly that is to be lifted vertically, such as when running or retrieving a tool string. The external profile on the upper section of the lifting sub is similar to that of the completion tubing, enabling the rig elevators to lift the assembled tool string safely.
368None
369None
370None
371--
372load cell
3731.n. [Well Workover and Intervention]
374The sensor component in a weight-indicator system that detects the tensional or compressional forces being imparted to the running string at surface. Load cells are hydraulically or electronically operated and are connected to the weight-indicator display system on the equipment operator's console.
375None
376None
377None
378--
379low gravity solids
3801.n. [Drilling Fluids]
381A type of drilling-fluid solid having a lower density than the barite or hematite that is used to weight up a drilling fluid, including drill solids plus the added bentonite clay. The mud engineer calculates the concentration of these and other types of solids on the basis of mud weight, retort analysis, chloride titrations and other information. Solids are reported as lbm/bbl or vol.%. Water is 1.0, barite 4.20, and hematite 5.505 g/cm3. Low-gravity solids are normally assumed to have a density of 2.60 g/cm3.
382None
383None
384LGS, low-gravity solids
385--
386landing nipple
3871.n. [Well Completions]
388A completion component fabricated as a short section of heavy wall tubular with a machined internal surface that provides a seal area and a locking profile. Landing nipples are included in most completions at predetermined intervals to enable the installation of flow-control devices, such as plugs and chokes. Three basic types of landing nipple are commonly used: no-go nipples, selective-landing nipples and ported or safety-valve nipples.
389no-go landing nipple, selective nipple
390None
391None
392--
393light crude oil
3941.n. [Production Testing]
395Crude oil that has a high API gravity, usually more than 40o.
396crude oil
397None
398None
399--
400local holdup
4011.n. [Production Logging]
402The fraction of a particular fluid measured in the vicinity of a small probe in a production well. The small, or local, probes respond digitally to the type of fluid in front of them, indicating gas, oil or water depending on the type of probe. The local holdup of oil, for example, is determined by the percentage of time the probe spends in front of oil.
403bubble count, electric probe, holdup image, local probe, optical probe, production log, velocity image
404None
405None
406--
407low solids mud
4081.n. [Drilling Fluids]
409A mud that has fewer solids than conventional clay-based muds of the same density and similar use. Low-solids mud design and maintenance is accomplished primarily by substituting one or more polymers for the ordinary bentonite clay. Viscosity can be obtained either entirely by polymers or by using a premium quality (nontreated) bentonite along with the appropriate extender polymer. Together, these give rheology comparable to that of a higher concentration of ordinary bentonite. Polyanionic cellulose (PAC) may be needed for fluid-loss control. XC polymer can be effective for cuttings carrying. By combining premium bentonite and the right extender polymer, PAC and XC polymer, solids can be kept low, if solids control is required. This concept applies best to low-density muds, below about 13 lbm/gal, but has some validity in all muds .
410None
411None
412low-solids mud
413--
414lao
4151.n. [Drilling Fluids]
416A synthetic hydrocarbon liquid made by the polymerization of ethylene, H2C=CH2. LAOs and other synthetic fluids are used in synthetic-base drilling fluids and other applications in which refined oils might otherwise be used if not for HSE concerns. LAOs have a linear structure with a double bond (olefin) at the end of the chain, making them more biodegradable than other olefins. LAOs can be catalytically reacted to move the double bond toward the center of the chain length to convert them to isomerized olefins, IOs.
417diesel-oil mud
418None
419linear alphaolefin
420--
421lignin
4221.n. [Drilling Fluids]
423The component of a tree that is extracted in the paper-manufacturing process and used as an additive in drilling fluids. Specifically, lignin is a highly polymerized, amorphous material that makes up the middle lamella of woody fibers and cements the fibers together. Methoxy groups are abundant on the lignin structure, giving lignin many reactive sites and promoting its water solubility. In paper manufacturing, lignin is dissolved from wood chips. In the sulfite paper process, the liquor byproduct contains wood sugars and lignosulfonate. The wood sugars are removed and the lignosulfonate is used as a clay deflocculant. In the kraft paper process, lignin is solubilized by caustic soda. Kraft lignin must be further reacted to make a functional drilling-fluid additive.
424caustic soda, Christmas tree, drilling fluid, emulsion mud, polymer, quebracho
425None
426None
427--
428local magnetic interference
4291.n. [Geophysics]
430Magnetic interference caused by nearby structures such as metallic rigs and wells. The magnetic permeability of drillstrings and the remanent magnetization in drillstrings contribute to perturbations of the measured magnetic field. Operators may use nonmagnetic drill collars to reduce these effects along with software techniques to compensate for them.
431main magnetic field, crustal magnetic field, external disturbance field
432None
433None
434--
435low specific gravity solids
4361.n. [Drilling Fluids]
437A type of drilling-fluid solid having a lower density than the barite or hematite that is used to weight up a drilling fluid, including drill solids plus the added bentonite clay. The mud engineer calculates the concentration of these and other types of solids on the basis of mud weight, retort analysis, chloride titrations and other information. Solids are reported as lbm/bbl or vol.%. Water is 1.0, barite 4.20, and hematite 5.505 g/cm3. Low-gravity solids are normally assumed to have a density of 2.60 g/cm3.
438material-balance equation, mud report, suspended solids
439None
440None
441--
442laplace equation
4431.n. [Geophysics]
444A partial differential equation that governs potential fields (in regions where there are no sources) and is equivalent, in three dimensions, to the inverse square law of gravitational or electrical attraction. In Cartesian coordinates, the Laplace equation equates the sum of the second partial (spatial) derivatives of the field to zero. (When a source is present, this sum is equal to the strength of the source and the resulting equation is called Poisson's equation). The differential equation is named for French mathematician Pierre-Simon de Laplace (1749 to 1827), and applies to electrical, gravity and magnetic fields.∇2u = ∂2u/∂x2 + ∂2u/∂y2 + ∂2u/∂z2 = 0,where u(x,y,z)is a potential function.
445potential field, spherical harmonic
446None
447None
448--
449lignosulfonate
4501.n. [Drilling Fluids]
451A highly anionic polymer used to deflocculate clay-based muds. Lignosulfonate is a byproduct of the sulfite method for manufacturing paper from wood pulp. Sometimes it is called sulfonated lignin. Lignosulfonate is a complex mixture of small- to moderate-sized polymeric compounds with sulfonate groups attached to the molecule. LS became a popular deflocculant in the late 1950s as a replacement for quebracho. Chromium and iron compounds were admixed to get stability benefits at higher temperature. These were called chrome lignosulfonates (CLS) and ferro-chrome lignosulfonates (FCLS). There is less chrome is in most CLS than in the past (now about 2.5 to 3 %), and chrome-free products are available.
452anion, buffered mud, carbonate ion, chrome lignosulfonate, clay-water interaction, conventional mud, deflocculated mud, emulsion mud, inhibitive mud, mud additive, prehydrated bentonite, seawater mud, sulfonated polystyrene-maleic anhydride copolymer
453None
454LS
455--
456local probe
4571.n. [Production Logging]
458A small sensor, part of a production logging tool, which determines the type of fluid in its vicinity as it moves up and down a production well. Typically there are four or more sensors, or probes, held on arms to measure the four quadrants of the well cross-section. The probes may be electrical, to distinguish hydrocarbon from water; optical, mainly to distinguish gas from liquid, but also oil from water; or dielectric, mainly to distinguish water from hydrocarbon, but also, with less resolution, oil from gas. They can detect bubbles that are larger than about 1 mm diameter. Their response is essentially digital, indicating either one fluid or the other, so that the percentage of time that they see a fluid is a direct measure of its holdup. The rate of change between the two fluids is known as the bubble count.The results can be averaged to give the mean holdup and bubble count, or converted into an image, showing the holdup or bubble count at different locations across the well at different depths. The image is particularly useful in highly deviated or horizontal wells where different flow regimes may be found in different quadrants.
459electric probe, holdup image, local holdup, optical probe, production log, velocity image
460None
461None
462--
463low velocity layer
4641.n. [Geophysics, Geology]
465Also known as weathered layer, a near-surface, possibly unconsolidated layer of low seismic velocity. The base of the weathered layer commonly coincides with the water table and a sharp increase in seismic velocity. The weathered layer typically has air-filled pores.
466pore, static correction, weathering, weathering correction
467None
468None
469--
470last shot detection
4711.n. [Perforating]
472A surface detection system used to ensure that all tubing-conveyed perforating guns have fired, from the top shot to the bottom shot.
473tubing-conveyed perforating
474None
475None
476--
477limestone compatible scale
4781.n. [Formation Evaluation]
479Display ranges chosen for the density and neutron porosity logs such that the two curves will overlay at all porosity values providing the matrix is pure calcite and the pores are filled with fresh water. The most common overlay spans two tracks, with the density reading from 1.95 to 2.95 g/cm3, and the neutron in limestone porosity units from 0.45 to −0.15 vol/vol.
480fresh water, limestone, limestone porosity unit, neutron porosity, sandstone porosity unit, sandstone-compatible scale, track
481None
482None
483--
484log
4851.vb. [Reservoir Characterization, Formation Evaluation, Drilling]
486To continuously measureformationproperties with electrically powered instruments to infer properties and make decisions about drilling andproductionoperations. The record of the measurements, typically a long strip of paper, is also called a log. Measurements include electrical properties (resistivity andconductivityat various frequencies),sonicproperties, active and passive nuclear measurements, dimensional measurements of the wellbore,formation fluidsampling,formation pressuremeasurement, wireline-conveyedsidewallcoring tools, and others. For wireline measurements, theloggingtool (or sonde) is lowered into the open wellbore on a multiple conductor, contra-helically armored wireline cable. Once the tool string (link to ID 2964) has reached the bottom of the interval of interest, measurements are taken on the way out of the wellbore. This is done in an attempt to maintain tension on thecable(which stretches) as constant as possible fordepth correlationpurposes. (The exception to this practice is in certain hostile environments in which the tool electronics might not survive the downhole temperatures for long enough to allow the tool to be lowered to the bottom of the hole and measurements to be recorded while pulling the tool up the hole. In this case, "down log" measurements might be conducted on the way into the well, and repeated on the way out if possible.) Most wireline measurements are recorded continuously while the sonde is moving. Certain fluid sampling and pressure-measuring tools require that the sonde be stopped, increasing the chance that the sonde or the cable might become stuck.Logging while drilling(LWD) tools take measurements in much the same way as wireline-logging tools, except that the measurements are taken by a self-contained tool near the bottom of thebottomhole assemblyand are recorded downward (as the well is deepened) rather than upward from the bottom of the hole.
487hostile environment, wireline log
488None
489None
490--
491log
4922.n. [Formation Evaluation]
493The measurement versus depth or time, or both, of one or more physical quantities in or around a well. The term comes from the word "log" used in the sense of a record or a note. Wireline logs are taken downhole, transmitted through a wireline to surface and recorded there. Measurements-while-drilling (MWD) and logging while drilling (LWD) logs are also taken downhole. They are either transmitted to surface by mud pulses, or else recorded downhole and retrieved later when the instrument is brought to surface. Mud logs that describe samples of drilled cuttings are taken and recorded on surface.
494real-time data, recorded data
495well log
496None
497--
498log
4993.n. [Formation Evaluation]
500The display of one or more log measurements on a strip of paper or film (a hard copy) with depth in one axis. In this sense, the term refers to the display not only of the measurement but of other relevant information. A typical log is presented on folded paper of indeterminate length, but about 8.5-in. [21.5-cm] wide. It consists of a heading, well sketch, logging tool sketch, insert, main log, repeat section and tail. When the term is used in this sense, each log measurement is usually referred to as a curve.
501None
502None
503None
504--
505log
5064.vb. [Formation Evaluation]
507To record a measurement versus depth or time, or both, of one or more physical quantities in or around a well.
508None
509survey
510None
511--
512log
5135.adj. [Formation Evaluation]
514Associated with the information from a log. For example, a log print is a paper print on which log data have been recorded.
515None
516None
517None
518--
519low yield clay
5201.n. [Drilling Fluids]
521Native clays that are generally unsuitable for use in a clay-based drilling mud. Low-yield clays are considered to be drill solids, although they may give high values for bentonite-equivalent in a mud according to the methylene blue test.
522None
523None
524low-yield clay
525--
526layer cake geometry
5271.n. [Reservoir Characterization]
528A highly simplified description of a geological scenario. Although sometimes used for "quick and dirty" simulation models, this description is often not appropriate for detailed or accurate work. Generally, layer-cake geometry is an oversimplification of actual structure and stratigraphy of a reservoir. It assumes that the reservoir comprises a stack of conformable layers.
529None
530None
531None
532--
533limestone porosity unit
5341.n. [Formation Evaluation]
535A transform from raw log data chosen so that a log recorded in these units will give the correct porosity of the formation, providing the matrix is pure calcite and the pores are filled with fresh water. The unit, which may be in vol/vol or p.u., is most commonly used for neutron porosity logs but may also be used for density and acoustic logs. The definition is strictly true only if all borehole and other environmental corrections have been applied.
536acoustic log, fresh water, limestone-compatible scale, neutron porosity, sandstone porosity unit, sandstone-compatible scale
537None
538None
539--
540logging tool
5411.n. [Formation Evaluation]
542The downhole hardware needed to make a log. The term is often shortened to simply "tool." Measurements-while-drilling (MWD) logging tools, in some cases known as logging while drilling (LWD) tools, are drill collars into which the necessary sensors and electronics have been built.Wireline logging tools are typically cylinders from 1.5 to 5 in. [3.8 to 12.7 cm] in diameter. Since the total length is more than can be conveniently handled in one piece, the logging tool is divided into different sections that are assembled at the wellsite. These sections consist of cartridges and sondes. Different measurements can be combined to make up a tool string. The total length of a tool string may range from 10 to 100 ft [3 to 30 m] or more. Flexible joints are added in long tool strings to ease passage in the borehole, and to allow different sections to be centralized or eccentralized. If the total length is very long, it is often preferable to make two or more logging runs with shorter tool strings.
543bridle, cable, drill collar, head, log, torpedo
544tool string
545None
546--
547low colloid oil mud
5481.n. [Drilling Fluids]
549An oil mud designed and maintained with a minimum of colloid-sized solids, typically by omitting fatty-acid soap and lime, and minimizing organophilic clays and fluid-loss additives. Low-colloid oil mud, also called a relaxed filtrate oil mud, increases drilling rate. A disadvantage is that filter cake formed on sands is not tight, can quickly become very thick, and can cause pipe to stick by differential pressure.
550differential pressure sticking, filtration, gilsonite, oil-mud emulsifier, organophilic clay
551relaxed-filtrate oil mud
552None
553--
554layer cake geometry
5551.n. [Reservoir Characterization]
556A highly simplified description of a geological scenario. Although sometimes used for "quick and dirty" simulation models, this description is often not appropriate for detailed or accurate work. Generally, layer-cake geometry is an oversimplification of actual structure and stratigraphy of a reservoir. It assumes that the reservoir comprises a stack of conformable layers.
557None
558None
559None
560--
561limestone compatible scale
5621.n. [Formation Evaluation]
563Display ranges chosen for the density and neutron porosity logs such that the two curves will overlay at all porosity values providing the matrix is pure calcite and the pores are filled with fresh water. The most common overlay spans two tracks, with the density reading from 1.95 to 2.95 g/cm3, and the neutron in limestone porosity units from 0.45 to −0.15 vol/vol.
564fresh water, limestone, limestone porosity unit, neutron porosity, sandstone porosity unit, sandstone-compatible scale, track
565None
566None
567--
568logging unit
5691.n. [Formation Evaluation]
570The cabin that contains the surface hardware needed to make wireline logging measurements. The logging unit contains at the minimum the surface instrumentation, a winch, a depth recording system and a data recorder. The surface instrumentation controls the logging tool, processes the data received and records the results digitally and on hard copy. The winch lowers and raises the cable in the well. A depth wheel drives the depth recording system. The data recorder includes a digital recorder and a printer.
571camera
572None
573None
574--
575low gravity solids
5761.n. [Drilling Fluids]
577A type of drilling-fluid solid having a lower density than the barite or hematite that is used to weight up a drilling fluid, including drill solids plus the added bentonite clay. The mud engineer calculates the concentration of these and other types of solids on the basis of mud weight, retort analysis, chloride titrations and other information. Solids are reported as lbm/bbl or vol.%. Water is 1.0, barite 4.20, and hematite 5.505 g/cm3. Low-gravity solids are normally assumed to have a density of 2.60 g/cm3.
578material-balance equation, mud report, suspended solids
579None
580None
581--
582lbmbbl
5831.n. [Drilling Fluids]
584The abbreviation for concentration in USoilfieldunits, pounds per barrel. One lbm/bbl is the equivalent of one pound of additive in 42 US gallons ofmud. The "m" is used to denote mass to avoid possible confusion with pounds force (denoted by "lbf"). Sometimes, lbm/bbl is written as ppb, but must not be confused with parts per billion. In SI units, the conversion factor is one pound per barrel equals 2.85 kilograms per cubic meter. For example, 10 lbm/bbl = 28.5 kg/m3.
585barrel equivalent, lb/bbl
586None
587pounds per barrel, ppb
588--
589limited entry
5901.n. [Well Testing]
591A completion with only a portion of the productive interval open to flow, either by design or as a result of damage. Limited-entry completions in vertical wells are designed to avoid unwanted fluid production, such as gas from an overlying gas cap or water from an underlying aquifer. The effects of limited entry may be seen in perforated and gravel-packed wells when some of the perforations fail to clean up. This is also called a partial completion. The limited entry also results from partial penetration, which occurs when the productive formation is only partly drilled. This partial penetration represents a near-well flow restriction that results in a positive skin effect in a well-test analysis.
592gas cap, gravel pack, partial completion, partial penetration, skin effect
593None
594None
595--
596logging while drilling
5971.n. [Drilling, Shale Gas]
598The measurement of formation properties during the excavation of the hole, or shortly thereafter, through the use of tools integrated into the bottomhole assembly. LWD, while sometimes risky and expensive, has the advantage of measuring properties of a formation before drilling fluids invade deeply. Further, many wellbores prove to be difficult or even impossible to measure with conventional wireline tools, especially highly deviated wells. In these situations, the LWD measurement ensures that some measurement of the subsurface is captured in the event that wireline operations are not possible.Timely LWD data can also be used to guide well placement so that the wellbore remains within the zone of interest or in the most productive portion of a reservoir, such as in highly variable shale reservoirs.
599bottomhole assembly, deviated hole, formation evaluation while drilling, measurements-while-drilling, wireline log
600None
601LWD
602--
603low pressure low temperature filtration test
6041.n. [Drilling Fluids]
605A test to measure static filtration behavior of water mud at ambient (room) temperature and 100-psi differential pressure, usually performed according to specifications set by API, using a static filter press. The filter medium is filter paper with 7.1 sq. in. filtering area. A half-size cell is sometimes used, in which case the filtrate volume is doubled.
606filter cake, filter medium, filter press, filter-cake quality, filter-cake thickness, filtrate, filtrate tracer, filtrate volume, filtration, fluid-loss control, fluid-loss-control material, relative filtrate volume, spurt loss, static filtration
607API fluid-loss test, static filter press
608Antonyms:high-pressure, high-temperature filtration test
609--
610lcm
6111.n. [Drilling, Drilling Fluids]
612Solid material intentionally introduced into a mud system to reduce and eventually prevent the flow of drilling fluid into a weak, fractured or vugular formation. This material is generally fibrous or plate-like in nature, as suppliers attempt to design slurries that will efficiently bridge over and seal loss zones. In addition, popular lost circulation materials are low-cost waste products from the food processing or chemical manufacturing industries. Examples of lost circulation material include ground peanut shells, mica, cellophane, walnut shells, calcium carbonate, plant fibers, cottonseed hulls, ground rubber, and polymeric materials.
613None
614None
615lost circulation material, lost-circulation material
616--
617line drive
6181.n. [Enhanced Oil Recovery]
619An injection pattern in which the injection wells are located in a straight line parallel to the production wells. In a line drive pattern, the injected fluid, which is normally water, steam or gas, creates a nearly linear frontal movement. A line drive pattern is also called direct line drive.
620injection pattern, injection well
621None
622None
623--
624logging while drilling
6251.adj. [Drilling, Shale Gas]
626The measurement of formation properties during the excavation of the hole, or shortly thereafter, through the use of tools integrated into the bottomhole assembly. LWD, while sometimes risky and expensive, has the advantage of measuring properties of a formation before drilling fluids invade deeply. Further, many wellbores prove to be difficult or even impossible to measure with conventional wireline tools, especially highly deviated wells. In these situations, the LWD measurement ensures that some measurement of the subsurface is captured in the event that wireline operations are not possible.Timely LWD data can also be used to guide well placement so that the wellbore remains within the zone of interest or in the most productive portion of a reservoir, such as in highly variable shale reservoirs.
627bottomhole assembly, deviated hole, formation evaluation while drilling, measurements-while-drilling, wireline log
628None
629logging while drilling, LWD
630--
631low salinity waterflooding
6321.n. [Enhanced Oil Recovery]
633An enhanced oil recovery method that uses water with a low concentration of dissolved salts as a flooding medium. The sources of low-salinity water are typically rivers, lakes or aquifers associated with meteoric water.
634waterflooding
635None
636None
637--
638lead cement
6391.n. [Drilling Fluids]
640Acementsystem used to providezonalisolation across generally nonproductive zones located above the zones of interest.
641fill cement
642None
643None
644--
645linear alphaolefin
6461.n. [Drilling Fluids]
647A synthetic hydrocarbon liquid made by the polymerization of ethylene, H2C=CH2. LAOs and other synthetic fluids are used in synthetic-base drilling fluids and other applications in which refined oils might otherwise be used if not for HSE concerns. LAOs have a linear structure with a double bond (olefin) at the end of the chain, making them more biodegradable than other olefins. LAOs can be catalytically reacted to move the double bond toward the center of the chain length to convert them to isomerized olefins, IOs.
648HSE, isomerized olefin, olefinic hydrocarbon, oligomer, polyalphaolefin, synthetic-base fluid, synthetic-base mud
649None
650LAO
651--
652long path multiple
6531.n. [Geophysics]
654A type of multiply-reflected seismic energy that appears as an event. Long-path multiples generate distinct events because their travel path is much longer than primary reflections giving rise to them. They typically can be removed by seismic processing.
655event, multiple reflection, noise, peg-leg multiple, primary reflection, short-path multiple, simple multiple
656None
657None
658--
659low solids mud
6601.n. [Drilling Fluids]
661A mud that has fewer solids than conventional clay-based muds of the same density and similar use. Low-solids mud design and maintenance is accomplished primarily by substituting one or more polymers for the ordinary bentonite clay. Viscosity can be obtained either entirely by polymers or by using a premium quality (nontreated) bentonite along with the appropriate extender polymer. Together, these give rheology comparable to that of a higher concentration of ordinary bentonite. Polyanionic cellulose (PAC) may be needed for fluid-loss control. XC polymer can be effective for cuttings carrying. By combining premium bentonite and the right extender polymer, PAC and XC polymer, solids can be kept low, if solids control is required. This concept applies best to low-density muds, below about 13 lbm/gal, but has some validity in all muds .
662acrylamide polymer, acrylamide-acrylate polymer, acrylate polymer, clay extender, conventional mud, low-solids, nondispersed mud, PHPA mud, water-base drilling fluid
663None
664None
665--
666leak off
6671.vb. [Drilling]
668The magnitude of pressure exerted on a formation that causes fluid to be forced into the formation. The fluid may be flowing into the pore spaces of the rock or into cracks opened and propagated into the formation by the fluid pressure. This term is normally associated with a test to determine the strength of the rock, commonly called a pressure integrity test (PIT) or a leakoff test (LOT). During the test, a real-time plot of injected fluid versus fluid pressure is plotted. The initial stable portion of this plot for most wellbores is a straight line, within the limits of the measurements. The leakoff is the point of permanent deflection from that straight portion. The well designer must then either adjust plans for the well to this leakoff pressure, or if the design is sufficiently conservative, proceed as planned.
669None
670None
671leakoff
672--
673linear flow
6741.n. [Well Testing]
675A flow regime characterized by parallel flow lines in the reservoir. This results from flow to a fracture or a long horizontal well, or from flow in an elongated reservoir, such as a fluvial channel, or as a formation bounded by parallel faults. Linear flow is recognized as a +1/2 slope in the pressure derivative on the log-log diagnostic plot. Its presence enables determination of the fracture half-length or the channel or reservoir width, if permeability can be determined independently.
676flow regime, flowline, fracture half-length
677None
678None
679--
680long spacing sonic log
6811.n. [Formation Evaluation]
682Log recorded by asonictool with a longer transmitter-to-receiverspacing(generally 10 to 15 ft) than a standard sonic tool. The rock near the borehole is sometimes altered by drilling fluids, stress relief, or both, causing a thin zone whose velocity is lower than that of the true formation. With standard spacings, the wave traveling through the altered zone may arrive first at the receiver, since this zone is closer to both transmitter and receiver. The increased spacing permits the wave traveling through the true formation to arrive first and be measured. The depth of investigation varies with slowness and transmitter-receiver spacing but is of the order of 2 to 3 ft. An increased transmitter-to-receiver spacing also allows better separation of waveforms relating to different acoustic waves, such as compressional, shear and Stoneley arrivals.
683full waveform, sonic log, sonic measurement
684None
685None
686--
687low specific gravity solids
6881.n. [Drilling Fluids]
689A type of drilling-fluid solid having a lower density than the barite or hematite that is used to weight up a drilling fluid, including drill solids plus the added bentonite clay. The mud engineer calculates the concentration of these and other types of solids on the basis of mud weight, retort analysis, chloride titrations and other information. Solids are reported as lbm/bbl or vol.%. Water is 1.0, barite 4.20, and hematite 5.505 g/cm3. Low-gravity solids are normally assumed to have a density of 2.60 g/cm3.
690material-balance equation, mud report, suspended solids
691None
692None
693--
694leakoff
6951.n. [Drilling]
696The magnitude of pressure exerted on a formation that causes fluid to be forced into the formation. The fluid may be flowing into the pore spaces of the rock or into cracks opened and propagated into the formation by the fluid pressure. This term is normally associated with a test to determine the strength of the rock, commonly called a pressure integrity test (PIT) or a leakoff test (LOT). During the test, a real-time plot of injected fluid versus fluid pressure is plotted. The initial stable portion of this plot for most wellbores is a straight line, within the limits of the measurements. The leakoff is the point of permanent deflection from that straight portion. The well designer must then either adjust plans for the well to this leakoff pressure, or if the design is sufficiently conservative, proceed as planned.
697leakoff test, LOT, PIT
698None
699leak off
700--
701liner
7021.n. [Drilling]
703A casing string that does not extend to the top of the wellbore, but instead is anchored or suspended from inside the bottom of the previous casing string. There is no difference between the casing joints themselves. The advantage to the well designer of a liner is a substantial savings in steel, and therefore capital costs. To save casing, however, additional tools and risk are involved. The well designer must trade off the additional tools, complexities and risks against the potential capital savings when deciding whether to design for a liner or a casing string that goes all the way to the top of the well (a "long string"). The liner can be fitted with special components so that it can be connected to the surface at a later time if need be.
704casing joint, casing string, reciprocate, underream
705None
706None
707--
708liner
7092.n. [Well Completions]
710Any string of casing in which the top does not extend to the surface but instead is suspended from inside the previous casing string. Many conventional well designs include a production liner set across the reservoir interval. This reduces the cost of completing the well and allows some flexibility in the design of the completion in the upper wellbore, such as when the fluid characteristics make it beneficial to increase the diameter of the conduit and components.
711None
712None
713None
714--
715longitudinal plot
7161.n. [Reservoir Characterization]
717A plot of the longitudinal component of the dip vector computed from a dipmeter. Longitudinal plots are used in the SCAT (Statistical Curvature Analysis Technique) method of interpreting dipmeter data for geological structure. They are especially useful in doubly plunging dip situations.
718None
719None
720None
721--
722low velocity layer
7231.n. [Geology, Geophysics]
724Also known as weathered layer, a near-surface, possibly unconsolidated layer of low seismic velocity. The base of the weathered layer commonly coincides with the water table and a sharp increase in seismic velocity. The weathered layer typically has air-filled pores.
725pore, static correction, weathering, weathering correction
726None
727None
728--
729leakoff test
7301.n. [Drilling]
731A test to determine the strength or fracture pressure of the open formation, usually conducted immediately after drilling below a new casing shoe. During the test, the well is shut in and fluid is pumped into the wellbore to gradually increase the pressure that the formation experiences. At some pressure, fluid will enter the formation, or leak off, either moving through permeable paths in the rock or by creating a space by fracturing the rock. The results of the leakoff test dictate the maximum pressure or mud weight that may be applied to the well during drilling operations. To maintain a small safety factor to permit safe well control operations, the maximum operating pressure is usually slightly below the leakoff test result.
732casing shoe, formation fracture pressure, fracture gradient, leakoff, mud weight
733PIT, pressure integrity test
734LOT
735--
736liner hanger
7371.n. [Well Completions]
738A device used to attach or hang liners from the internal wall of a previous casing string. Liner hangers are available in a range of sizes and specifications to suit a variety of completion conditions.
739casing string, liner
740None
741None
742--
743longitudinal relaxation
7441.n. [Formation Evaluation]
745During a nuclear magnetic resonance measurement, the loss of energy by hydrogen atoms in a rock as they align themselves with the static magnetic field. The atoms behave like spinning bar magnets so that when a static magnetic field is applied, they initially precess about the field. Then, through interactions with nuclei and electrons, they lose energy, or relax, and align themselves with the magnetic field. The relaxation of the hydrogen atoms does not occur immediately but grows exponentially with a time constant T1. There are two mechanisms for longitudinal relaxation, surface relaxation and bulk relaxation.
746relaxation time, transverse relaxation
747None
748None
749--
750low yield clay
7511.n. [Drilling Fluids]
752Native clays that are generally unsuitable for use in a clay-based drilling mud. Low-yield clays are considered to be drill solids, although they may give high values for bentonite-equivalent in a mud according to the methylene blue test.
753bentonite, clay-water interaction, methylene blue test, yield
754None
755None
756--
757leaky mode
7581.n. [Formation Evaluation]
759A type of acoustic energy that propagates in one direction while being confined in the other two directions, in this case by the borehole wall. Leaky modes can be considered as multiply reflected and constructively interfering waves propagating in the borehole. Each time a compressional wave hits the borehole wall, part of the energy is reflected into the borehole, while the rest is converted to compressional or shear energy that radiates into the formation, hence the term 'leaky'. Leaky modes are dispersive, starting at a certain cutoff frequency with the formation compressional velocity and increasing towards the borehole fluid velocity at high frequency. In slow formations, where no head wave is generated because the borehole fluid is faster than the formation compressional wave, the low-frequency end of the leaky mode can be used to determine formation compressional velocity.The term 'hybrid mode' is used to describe a form of leaky mode that is associated with an altered zone.
760acoustic mode, altered zone, flexural mode, head wave, normal mode, Stoneley wave, tube wave
761None
762None
763--
764lipophilic
7651.adj. [Enhanced Oil Recovery, Drilling Fluids]
766Pertaining to an attraction for oil by a surface of a material or a molecule. This term is applied to the oil-wetting behavior of treatment chemicals for oil muds. Lipophilic oil-mud additives are required because most minerals drilled and additives such as barite are naturally hydrophilic and must be rendered lipophilic.
767HLB number, hydrophile-lipophile balance number, lyophilic, oil mud, oil-wet
768None
769Antonyms:hydrophilic
770--
771long path multiple
7721.n. [Geophysics]
773A type of multiply-reflected seismic energy that appears as an event. Long-path multiples generate distinct events because their travel path is much longer than primary reflections giving rise to them. They typically can be removed by seismic processing.
774event, multiple reflection, noise, peg-leg multiple, primary reflection, short-path multiple, simple multiple
775None
776None
777--
778ls
7791.n. [Drilling Fluids]
780A highly anionic polymer used to deflocculate clay-based muds. Lignosulfonate is a byproduct of the sulfite method for manufacturing paper from wood pulp. Sometimes it is called sulfonated lignin. Lignosulfonate is a complex mixture of small- to moderate-sized polymeric compounds with sulfonate groups attached to the molecule. LS became a popular deflocculant in the late 1950s as a replacement for quebracho. Chromium and iron compounds were admixed to get stability benefits at higher temperature. These were called chrome lignosulfonates (CLS) and ferro-chrome lignosulfonates (FCLS). There is less chrome is in most CLS than in the past (now about 2.5 to 3 %), and chrome-free products are available.
781None
782None
783lignosulfonate
784--
785lean gas
7861.n. [Production Testing]
787Natural gas that contains a few or no liquefiable liquid hydrocarbons. Lean gas is also called dry gas.
788liquid hydrocarbons, natural gas
789None
790dry gas
791--
792lean gas
7932.n. [Production Testing]
794Residual gas, mainly methane and ethane, that remains after the heavier hydrocarbons have been condensed in the wellhead. When the lean gas is liquefied, it is called liquefied natural gas (LNG).
795liquefied natural gas, LNG
796None
797None
798--
799liquefied petroleum gas
8001.n. [Production Testing]
801Gas mainly composed of propane and butane, which has been liquefied at low temperatures and moderate pressures. The gas is obtainable from refinery gases or after the cracking process of crude oil.Liquefied petroleum gas is also called bottle gas. At atmospheric pressure, it is easily converted into gas and can be used industrially or domestically. The term is commonly abbreviated as LPG.
802crude oil
803None
804LPG
805--
806long spacing sonic log
8071.n. [Formation Evaluation]
808Log recorded by asonictool with a longer transmitter-to-receiverspacing(generally 10 to 15 ft) than a standard sonic tool. The rock near the borehole is sometimes altered by drilling fluids, stress relief, or both, causing a thin zone whose velocity is lower than that of the true formation. With standard spacings, the wave traveling through the altered zone may arrive first at the receiver, since this zone is closer to both transmitter and receiver. The increased spacing permits the wave traveling through the true formation to arrive first and be measured. The depth of investigation varies with slowness and transmitter-receiver spacing but is of the order of 2 to 3 ft. An increased transmitter-to-receiver spacing also allows better separation of waveforms relating to different acoustic waves, such as compressional, shear and Stoneley arrivals.
809full waveform, sonic log, sonic measurement
810None
811None
812--
813lubricator
8141.n. [Drilling]
815A long, high-pressure pipe fitted to the top of a wellhead or Christmas tree so that tools may be put into a high-pressure well. The top of the lubricator assembly includes a high-pressure grease-injection section and sealing elements. The lubricator is installed on top of the tree and tested, the tools placed in the lubricator and the lubricator pressurized to wellbore pressure. Then the top valves of the tree are opened to enable the tools to fall or be pumped into the wellbore under pressure. To remove the tools, the reverse process is used: the tools are pulled up into the lubricator under wellbore pressure, the tree valves are closed, the lubricator pressure is bled off, and then the lubricator may be opened to remove the tools.
816None
817None
818None
819--
820lubricator
8212.n. [Well Workover and Intervention]
822A term initially applied to the assembly of pressure-control equipment used on slickline operations to house the tool string in preparation for running into the well or for retrieval of the tool string on completion of the operation. The lubricator is assembled from sections of heavy-wall tube generally constructed with integral seals and connections. Lubricator sections are routinely used on the assembly of pressure-control equipment for other well-intervention operations such as coiled tubing.
823None
824None
825None
826--
827lease
8281.vt. [Geology]
829The act of acquiring acreage for exploration or production activity.
830licensing round
831None
832None
833--
834lease
8352.n. [Geology]
836An area of surface land on which exploration or production activity occurs.
837None
838None
839None
840--
841lease
8423.n. [Geology]
843The contract that conveys the rights to explore and produce from the owner of the mineral rights (lessor) to a tenant (lessee), usually for a fee and with a specified duration. A lease usually includes a provision for sharing production.
844licensing round
845None
846None
847--
848liquid blocking
8491.n. [Heavy Oil, Enhanced Oil Recovery]
850A phenomenon encountered during dry forward combustion in which an oil zone around the production well cannot be pushed forward by the heated oil. The fluid located in this zone is still at the original reservoir temperature. Therefore, the fluid is still highly viscous and normally not mobile.
851in-situ combustion, reverse combustion
852None
853None
854--
855lost circulation
8561.n. [Drilling]
857The reduced or total absence of fluid flow up the annulus when fluid is pumped through the drillstring. Though the definitions of different operators vary, this reduction of flow may generally be classified as seepage (less than 20 bbl/hr [3 m3/hr]), partial lost returns (greater than 20 bbl/hr [3 m3/hr] but still some returns), and total lost returns (where no fluid comes out of the annulus). In this severe latter case, the hole may not remain full of fluid even if the pumps are turned off. If the hole does not remain full of fluid, the vertical height of the fluid column is reduced and the pressure exerted on the open formations is reduced. This in turn can result in another zone flowing into the wellbore, while the loss zone is taking mud, or even a catastrophic loss of well control. Even in the two less severe forms, the loss of fluid to the formation represents a financial loss that must be dealt with, and the impact of which is directly tied to the per barrel cost of the drilling fluid and the loss rate over time.
858air drilling, bullhead, cementing, thief zone, well control
859None
860None
861--
862lost circulation
8632.n. [Drilling Fluids]
864A lack of mud returning to the surface after being pumped down a well. Lost circulation occurs when the drill bit encounters natural fissures, fractures or caverns, and mud flows into the newly available space. Lost circulation may also be caused by applying more mud pressure (that is, drilling overbalanced) on the formation than it is strong enough to withstand, thereby opening up a fracture into which mud flows.
865bridging material, circulation loss, fiber lost-circulation material, flake lost-circulation material, granular lost-circulation material, gunk plug, gunk squeeze, hydrostatic pressure, lost-circulation material, mud weight, pill, shear strength, shear-strength measurement test
866lost returns
867None
868--
869lwd
8701.n. [Drilling, Shale Gas]
871Abbreviation for logging while drilling. The measurement of formation properties during the excavation of the hole, or shortly thereafter, through the use of tools integrated into the bottomhole assembly. LWD, while sometimes risky and expensive, has the advantage of measuring properties of a formation before drilling fluids invade deeply. Further, many wellbores prove to be difficult or even impossible to measure with conventional wireline tools, especially highly deviated wells. In these situations, the LWD measurement ensures that some measurement of the subsurface is captured in the event that wireline operations are not possible. Timely LWD data can also be used to guide well placement so that the wellbore remains within the zone of interest or in the most productive portion of a reservoir, such as in highly variable shale reservoirs.
872deviated hole, measurements-while-drilling, wireline log
873None
874logging while drilling
875--
876least time path
8771.n. [Geophysics]
878The fastest route that a seismic ray can travel between two points, generally dictated by Fermat's principle.
879Fermat's principle, Snell's law
880None
881None
882--
883listric fault
8841.n. [Geology]
885A normal fault that flattens with depth and typically found in extensional regimes. This flattening manifests itself as a curving, concave-up fault plane whose dip decreases with depth.
886normal fault, growth fault
887None
888None
889--
890lost circulation material
8911.n. [Drilling]
892Solid material intentionally introduced into a mud system to reduce and eventually prevent the flow of drilling fluid into a weak, fractured or vugular formation. This material is generally fibrous or plate-like in nature, as suppliers attempt to design slurries that will efficiently bridge over and seal loss zones. In addition, popular lost circulation materials are low-cost waste products from the food processing or chemical manufacturing industries. Examples of lost circulation material include ground peanut shells, mica, cellophane, walnut shells, calcium carbonate, plant fibers, cottonseed hulls, ground rubber, and polymeric materials.
893bridging material, pill
894None
895LCM, lost-circulation material
896--
897lyophilic
8981.adj. [Drilling Fluids]
899A descriptive term for the strong affinity that a solid material (usually a colloid) has for the liquid in which the solid is dispersed. For example, clay is a lyophilic colloid in water.
900hydrophilic, lipophilic, lyophilic colloid, organophilic, organophilic lignite, surfactant
901None
902None
903--
904least time path
9051.n. [Geophysics]
906The fastest route that a seismic ray can travel between two points, generally dictated by Fermat's principle.
907Fermat's principle, Snell's law
908None
909None
910--
911mafic
9121.adj. [Geology]
913Pertaining to minerals or igneous rocks composed of minerals that are rich in iron and magnesium, dense, and typically dark in color. The term comes from the words magnesium and ferric. Common mafic minerals are olivine and pyroxene. Basalt is a mafic igneous rock. (Compare with felsic.)
914felsic, igneous, midoceanic ridge, mineral
915None
916None
917--
918metagenesis
9191.n. [Shale Gas]
920The last stage of maturation and conversion of organic matter to hydrocarbons. Metagenesis occurs at temperatures of 150° to 200&degC [302° to 392&degF]. At the end of metagenesis, methane, or dry gas, is evolved along with nonhydrocarbon gases such as CO2, N2, and H2S, as oil molecules are cracked into smaller gas molecules.
921None
922None
923None
924--
925minimum time path
9261.n. [Geophysics]
927The fastest route that a seismic ray can travel between two points, generally dictated by Fermat's principle.
928Fermat's principle, least-time path, Snell's law
929None
930None
931--
932mud aging cell
9331.n. [Drilling Fluids]
934A cylindrical vessel in which a mud sample can be heated under pressure. Cells, often called bombs, are routinely used for static-aging and hot-roll aging of mud samples. Cells are usually made of metal or metal alloy, such as stainless steel or aluminum bronze, and have open tops. Caps should be fitted with a valve so that gas pressure can be applied and then released before opening the cell. Common sizes are 260 and 500 cm3, to accommodate half- and one-barrel equivalent volumes, plus space for thermal expansion. Glass or plastic jars can be used judiciously when pressure is nil and temperature is limited to below about 150°F [66°C].
935None
936None
937mud-aging cell
938--
939magnetic constant
9401.n. [Geophysics]
941Another term for magnetic permeability, the ratio of the density of the magnetic flux, B (in units of teslas), to the strength of the magnetic field, H (in units of amperes/meter), typically expressed in units of H/m.
942magnetics, skin depth
943None
944None
945--
946metal gain
9471.n. [Production Logging]
948The apparent increase in thickness of a casing or tubing string compared to the assumed value. Metal gain is determined by electromagnetic thickness, acoustic resonance or mechanical methods. The apparent increase is usually due a change of hardware, such as a casing coupling, a heavier joint, a pup joint, a mandrel or a valve. The term is used in contrast to metal loss caused by corrosion.
949casing-inspection log, electromagnetic thickness, multifinger caliper, ultrasonic caliper
950None
951Antonyms:metal loss, wall loss
952--
953minimum time path
9541.n. [Geophysics]
955The fastest route that a seismic ray can travel between two points, generally dictated by Fermat's principle.
956Fermat's principle, Snell's law
957None
958None
959--
960mud cell
9611.n. [Drilling Fluids]
962Another term for mud-aging cell, a cylindrical vessel in which a mud sample can be heated under pressure. Cells, often called bombs, are routinely used for static-aging and hot-roll aging of mud samples. Cells are usually made of metal or metal alloy, such as stainless steel or aluminum bronze, and have open tops. Caps should be fitted with a valve so that gas pressure can be applied and then released before opening the cell. Common sizes are 260 and 500 cm3, to accommodate half- and one-barrel equivalent volumes, plus space for thermal expansion. Glass or plastic jars can be used judiciously when pressure is nil and temperature is limited to below about 150°F [66°C].
963barrel equivalent, bomb, bottoms-up mud sample, mud oven, pilot test, rolling-aging test, shear-strength measurement test, static-aging test, temperature stability
964None
965mud-aging cell
966--
967magnetic flux leakage
9681.n. [Production Logging]
969A distortion of the magnetic flux that has been introduced into a casing by a low-frequency electromagnet or permanent magnet. The principle of flux leakage is used to detect casing corrosion, since flux leakage is caused by rapid changes in the thickness of the casing and by pits and holes in either the internal or external wall. Flux leakage distorts the magnetic-flux lines and induces a signal into an electric coil moving past it. In-situ flux-leakage measurements make use of this effect by placing coils on or close to the casing wall, azimuthally distributed to cover the entire wall. The results are often combined with a high-frequency, eddy-current measurement, designed to detect flaws only on the inner wall.
970azimuthal, casing-inspection log, casing-potential profile, eddy current, eddy-current measurement, pitting
971None
972None
973--
974metamorphic
9751.adj. [Geology]
976One of three main classes of rock (igneous, metamorphic and sedimentary). Metamorphic rocks form from the alteration of preexisting rocks by changes in ambient temperature, pressure, volatile content, or all of these. Such changes can occur through the activity of fluids in the Earth and movement of igneous bodies or regional tectonic activity. The texture of metamorphic rocks can vary from almost homogeneous, or nonfoliated, to foliated rocks with a strong planar fabric or foliation produced by alignment of minerals during recrystallization or by reorientation. Common foliated metamorphic rocks include gneiss, schist and slate. Marble, or metamorphosed limestone, can be foliated or non-foliated. Hornfels is a nonfoliated metamorphic rock. Graphite, chlorite, talc, mica, garnet and staurolite are distinctive metamorphic minerals.
977basement, chlorite, feldspar, hard rock, igneous, massif, metamorphism, mica, nonconformity, plate tectonics, reservoir, rock, sedimentary, soft rock, unconformity
978None
979None
980--
981minute mark
9821.n. [Formation Evaluation]
983An annotation made on a log print once every minute. By reading the depth interval between each minute mark, it is possible to check the logging speed. Minute marks are typically made by blanking out the vertical grid line on the far left of the print for a short interval every minute.
984None
985None
986None
987--
988mud density
9891.n. [Drilling Fluids]
990The mass per unit volume of a drilling fluid, synonymous with mud weight. Weight is reported in lbm/gal (also known as ppg), kg/m3 or g/cm3 (also called specific gravity or SG), lb/ft3 or in hydrostatic gradient, lb/in2/ft (psi/ft) or pptf (psi/1000 ft). Mud weight controls hydrostatic pressure in a wellbore and prevents unwanted flow into the well. The weight of the mud also prevents collapse of casing and the openhole. Excessive mud weight can cause lost circulation by propagating, and then filling, fractures in the rock. Mud weight (density) test procedures using a mud balance have been standardized and published by the API.
991bland coring fluid, calcium bromide, cesium acetate, cesium formate, equivalent circulating density, formate, gunning the pits, high-gravity solids, kill-weight fluid, kilogram per cubic meter, mud, mud balance, mud program, pressurized mud balance, PVT, sag, slug, weighting material
992None
993mud weight
994--
995magnetic permeability
9961.n. [Geophysics]
997The ratio of the density of the magnetic flux, B (in units of teslas), to the strength of the magnetic field, H (in units of amperes/meter), typically expressed in units of henries per meter (H/m).
998magnetics, skin depth
999None
1000None
1001--
1002metamorphism
10031.n. [Geology]
1004The process by which the characteristics of rocks are altered or the rock is recrystallized. Metamorphism of igneous, sedimentary, or preexisting metamorphic rock can produce new metamorphic rock. Such alteration occurs as rocks respond to changes in temperatures, pressures and fluids, commonly along the edges of colliding lithospheric plates. The pressures and temperatures at which metamorphism occurs are higher than those of diagenesis, but no clear boundary between the two has been established.
1005cataclastic, diagenesis, maturity, metamorphic, overmature, post-mature
1006None
1007None
1008--
1009miscible
10101.adj. [Enhanced Oil Recovery, Geology]
1011Pertaining to a condition in which two or more fluids can mix in all proportions and form a single homogeneous phase.
1012multiple-contact miscibility
1013None
1014Antonyms:immiscible
1015--
1016mud hopper
10171.n. [Drilling Fluids]
1018A mud-flow device, also called a jet hopper, in which materials are put into the circulating mud system. The mud hopper is powered by a centrifugal pump that flows the mud at high velocity through a venturi nozzle (jet) below the conical-shaped hopper. Dry materials are added through the mud hopper to provide dispersion, rapid hydration and uniform mixing. Liquids are sometimes fed into the mud by a hose placed in the hopper.
1019hopper, mud, prehydrated bentonite
1020None
1021None
1022--
1023magnetic reversal sequence
10241.n. [Geology]
1025The periodic switching of the magnetic north and south poles of the Earth throughout time, probably as a result of movement of fluid within the Earth's core. The onset and duration of the many episodes of reversed polarity have been documented by examining the polarity of magnetic minerals within rocks of different ages from around the world, particularly in basalts or igneous rocks of the oceanic crust. Oceanic basalts record the Earth's magnetic field as they solidify from molten lava symmetrically on each side of the midoceanic ridges. These data have been compiled to create a time scale known as the geomagnetic polarity time scale (GPTS). In the oil field, borehole recordings allow direct correlation to GPTS and well-to-well correlations.
1026geochronology, geologic time scale, geomagnetic polarity time scale, midoceanic ridge, natural remanent magnetism
1027None
1028None
1029--
1030methane hydrate
10311.n. [Geology]
1032An unusual occurrence ofhydrocarbonin which molecules ofmethane are trapped in ice molecules. More generally, hydrates are compounds in which gas molecules are trapped within a crystal structure. Hydrates form in cold climates, such aspermafrostzones and in deep water. To date, economic liberation of hydrocarbon gases from hydrates has not occurred, but hydrates contain quantities of hydrocarbons that could be of great economic significance. Hydrates can affectseismic data by creating areflectionor multiple.
1033clathrate, gas hydrate, natural gas
1034None
1035None
1036--
1037methane hydrate
10382.n. [Production Testing]
1039A compound or complex ion that is formed by the union of water with methane. Hydrates can form in pipelines and in gas gathering, compression and transmission facilities at reduced temperatures and high pressures. Once hydrates are formed, they can plug the pipelines and significantly affect production operations.
1040gas hydrate
1041None
1042None
1043--
1044methane hydrate
10453.n. [Drilling Fluids]
1046A crystalline solid consisting of water with methane molecules in an ice-like cage structure. The general term for this type of solid is clathrate. Water molecules form a lattice structure into which many types of gas molecules can fit. Most gases, except hydrogen and helium, can form hydrates. C1tonC5hydrocarbons, H2S and CO2readily form hydrates at low temperature and highpressure. Heavier hydrocarbons may also enter the structure but do not form hydrates by themselves. Gas-cutmuds can form hydrates in deepwater drilling operations, pluggingBOPlines, risers and subsea wellheads, causing a well-control risk. Gas hydrates are thermodynamically suppressed by adding antifreeze materials such as salts or glycols. A common practice is to use 20 to 23 wt.% NaCl. Nucleation and growth of hydrates can be dynamically inhibited by certain polymers or surfactants. Gas hydrates are found in nature, on the bottom of cold seas and in arcticpermafrostregions. Drilling into these can be hazardous, but they offer another source of hydrocarbons for future exploitation.Reference:Ebeltoft H, Yousif M and Soergaard E: "Hydrate Control During Deep-water Drilling: Overview and New Drilling Fluids Formulations," paper SPE 38567, presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, October 5-8, 1997.
1047clathrate, drilling riser, gas hydrate, gas-cut mud, glycol, polymer, surfactant
1048None
1049None
1050--
1051miscible displacement
10521.n. [Enhanced Oil Recovery]
1053A general term for injection processes that introduce miscible gases into the reservoir. A miscible displacement process maintains reservoir pressure and improves oil displacement because the interfacial tension between oil and water is reduced. The effect of gas injection is similar to that of a solution gasdrive.Miscible displacement is a major branch of enhanced oil recovery processes. Injected gases include liquefied petroleum gas (LPG), such as propane, methane under high pressure, methane enriched with light hydrocarbons, nitrogen under high pressure, and carbon dioxide [CO2] under suitable reservoir conditions of temperature and pressure. The fluid most commonly used for miscible displacement is carbon dioxide because it reduces the oil viscosity and is less expensive than liquefied petroleum gas.Miscible displacement is also called miscible gasdrive, miscible drive or miscible flood.
1054chemical flooding, gas injection, liquefied petroleum gas, miscible, reservoir pressure, thermal recovery
1055None
1056None
1057--
1058mud in
10591.n. [Drilling Fluids]
1060Themudflowing into the well. The mud-in sample is taken from the suction pit (the last pit in the flow series) just before the mud goes into the pump and down the wellbore. The in sample is also called the suction-pit sample, or "mud in" on adrilling fluidreport. This mud has been treated and properly weighted and is in good condition to encounter downhole pressures, temperatures and contamination. Comparisons are made between properties of this mud-in sample and the "out" ormud-out sample taken at surface prior to solids removal.
1061mud-in sample
1062None
1063None
1064--
1065magnetic flux leakage
10661.n. [Production Logging]
1067A distortion of the magnetic flux that has been introduced into a casing by a low-frequency electromagnet or permanent magnet. The principle of flux leakage is used to detect casing corrosion, since flux leakage is caused by rapid changes in the thickness of the casing and by pits and holes in either the internal or external wall. Flux leakage distorts the magnetic-flux lines and induces a signal into an electric coil moving past it. In-situ flux-leakage measurements make use of this effect by placing coils on or close to the casing wall, azimuthally distributed to cover the entire wall. The results are often combined with a high-frequency, eddy-current measurement, designed to detect flaws only on the inner wall.
1068azimuthal, casing-inspection log, casing-potential profile, eddy current, eddy-current measurement, pitting
1069None
1070None
1071--
1072micellar polymer flooding
10731.n. [Enhanced Oil Recovery]
1074An enhanced oil recovery technique in which a micelle solution is pumped into a reservoir through specially distributed injection wells. The chemical solution reduces the interfacial and capillary forces between oil and water and triggers an increase in oil production.The procedure of a micellar-polymer flooding includes a preflush (low-salinity water), a chemical solution (micellar or alkaline), a mobility buffer and, finally, a driving fluid (water), which displaces the chemicals and the resulting oil bank to production wells.
1075None
1076None
1077micellar-polymer flooding
1078--
1079mist
10801.n. [Production Facilities]
1081Small liquid droplets (moisture or liquid hydrocarbons) in a gas stream. In separators, mist extractors are used to collect mist.
1082three-phase separator, two-phase separator
1083None
1084None
1085--
1086mud in sample
10871.n. [Drilling Fluids]
1088A mud sample taken from the suction pit (the last pit in the flow series) just before the mud goes into the pump and down the wellbore. The in sample is also called the suction-pit sample, or "mud in" on a drilling fluid report. This mud has been treated and properly weighted and is in good condition to encounter downhole pressures, temperatures and contamination. Comparisons are made between properties of this mud-in sample and the "out" or mud-out sample taken at surface prior to solids removal.
1089bottoms-up mud sample, cycle time, flowline mud sample, lag time, mud in, pilot test
1090None
1091None
1092--
1093magnetotelluric method
10941.n. [Geophysics]
1095An electromagnetic method used to map the spatial variation of the Earth's resistivity by measuring naturally occurring electric and magnetic fields at the Earth's surface. These natural EM fields are generated (at all frequencies) in the Earth's atmosphere mainly by lightning strokes and by interactions between the solar wind and the ionosphere. In the most general MT method, the horizontal components of the electric field and all three components of the magnetic field are measured at the surface. The measurements are used to determine specific ratios of electric to magnetic field components called tensor impedances. The technique was introduced the French geophysicist Louis Cagniard in the 1950s and has been popular for mineral exploration and regional geophysical mapping. It is used in oil exploration for low-cost reconnaissance of sedimentary basins and for exploration in areas where seismic surveys are difficult because of severe topography or the presence high-impedance volcanic rocks near the surface. The resolution of MT surveys is limited by the diffusive nature of EM propagation in the earth; it is usually on the order of hundreds of meters to kilometers. But the MT method can probe the Earth to depths of several tens of kilometers.
1096electromagnetic method, Occam's inversion, probe
1097None
1098MT
1099--
1100micellar polymer flooding
11011.n. [Enhanced Oil Recovery, Enhanced Oil Recovery]
1102An enhanced oil recovery technique in which a micelle solution is pumped into a reservoir through specially distributed injection wells. The chemical solution reduces the interfacial and capillary forces between oil and water and triggers an increase in oil production.The procedure of a micellar-polymer flooding includes a preflush (low-salinity water), a chemical solution (micellar or alkaline), a mobility buffer and, finally, a driving fluid (water), which displaces the chemicals and the resulting oil bank to production wells.
1103alkaline flooding, buffer, chemical flooding, micelle, surfactant
1104None
1105None
1106--
1107mist drilling
11081.n. [Drilling]
1109A variation of air drilling in which a small amount of water trickles into the wellbore from exposed formations and is carried out of the wellbore by the compressed air used for air drilling. The onset of mist drilling often signals the impending end of practical air drilling, at which point the water inflow becomes too great for the compressed air to remove from the wellbore, or the produced water (usually salty) becomes a disposal problem.
1110air drilling, mist
1111None
1112None
1113--
1114mud out sample
11151.n. [Drilling Fluids]
1116A mud sample taken after it has passed from the flowline and through the shale shaker screens to remove large cuttings. The out sample is also called the shale shaker sample. This mud has experienced the downhole pressures, temperatures and contamination that cause degradation. It is evaluated for needed treatments and compared, on a lagged time basis, with the corresponding "in" or mud-in sample.
1117bottoms-up mud sample, cycle time, lag time, mud out, pilot test
1118None
1119flowline mud sample, flowline sample
1120--
1121make a connection
11221.vb. [Drilling]
1123To add a length of drillpipe to the drillstring to continue drilling. In what is called jointed pipe drilling, joints of drillpipe, each about 30 ft [9 m] long, are screwed together as the well is drilled. When the bit on the bottom of the drillstring has drilled down to where the kelly or topdrive at the top of the drillstring nears the drillfloor, the drillstring between the two must be lengthened by adding a joint or a stand (usually three joints) to the drillstring. Once the rig crew is ready, the driller stops the rotary, picks up off bottom to expose a threaded connection below the kelly and turns the pumps off. The crew sets the slips to grip the drillstring temporarily, unscrews that threaded connection and screws the kelly (or topdrive) into the additional joint (or stand) of pipe. The driller picks that joint or stand up to allow the crew to screw the bottom of that pipe into the top of the temporarily hanging drillstring. The driller then picks up the entire drillstring to remove the slips, carefully lowers the drillstring while starting the pumps and rotary, and resumes drilling when the bit touches bottom. A skilled rig crew can physically accomplish all of those steps in a minute or two.
1124joint, kelly, mousehole, slips, stand, topdrive
1125None
1126None
1127--
1128micrite
11291.n. [Geology]
1130Dense, fine-grained carbonate mud or rocks composed of mud that forms by erosion of larger carbonate grains, organic precipitation (such as from algae), or inorganic precipitation. The grains in micrite are generally less than 4 microns in size.
1131carbonate, carbonate, erosion, erosion, limestone
1132None
1133None
1134--
1135mist extractor
11361.n. [Production Facilities]
1137A device used to collect small liquid droplets (moisture or hydrocarbons) from the gas stream before it leaves the separator. The two most common types of mist extractors are wire-mesh pads and vanes. Once the small droplets of liquid are collected, they are removed along with the other liquids from the separator.
1138None
1139None
1140None
1141--
1142mud oven
11431.n. [Drilling Fluids]
1144An oven into which mud-testing cells are placed. Ovens usually have a set of horizontal rollers inside and are also called roller ovens. Mud-aging cells are placed on the rollers. In pilot tests, rolling the cells allows a film of mud to continually contact the hot wall of the cell. Another type of oven tumbles cells end-to-end. Most ovens can also be used for static-aging tests.
1145mud-aging cell, pilot test, rolling-aging test, static-aging test
1146None
1147None
1148--
1149makeup tongs
11501.n. [Drilling]
1151Large-capacity, self-locking wrenches used to grip drillstring components and apply torque. As with opposing pipe wrenches for a plumber, the tongs must be used in opposing pairs. As a matter of efficiency, one set of tongs is essentially tied off with a cable or chain to the derrick, and the other is actively pulled with mechanical catheads. The breakout tongs are the active tongs during breakout (or loosening) operations. The makeup tongs are active during makeup (or tightening) operations.
1152breakout tongs, cat line, cathead, chain tongs, derrick, makeup cathead, tool joint
1153None
1154None
1155--
1156microannulus
11571.n. [Well Completions]
1158A small gap that can form between the casing or liner and the surrounding cement sheath, most commonly formed by variations in temperature or pressure during or after the cementing process. Such variations cause small movement of the steel casing, breaking the cement bond and creating a microannulus that is typically partial. However, in severe cases the microannulus may encircle the entire casing circumference. A microannulus can jeopardize the hydraulic efficiency of a primary cementing operation, allowing communication between zones if it is severe and connected.
1159None
1160None
1161None
1162--
1163mist flow
11641.n. [Well Completions]
1165A multiphase fluid-flow regime characterized by the gas phase being distributed as bubbles through the liquid phase. In a producing wellbore where the bubbles are uniformly distributed, there is little relative motion between the phases. Where the bubbles congregate and combine to form a less uniform distribution of the gas phase, some slippage will occur between the phases with the gas tending to cut through the liquid phase.
1166multiphase fluid, slip
1167None
1168None
1169--
1170mist flow
11712.n. [Production Logging]
1172A multiphase-flow regime, with gas as the continuous phase, in which oil or water exists as very small, approximately homogeneously distributed droplets. Mist flow occurs at high gas velocities. Unless the velocity is very high, there may be a thin film of liquid on the pipe wall, in which case the term annular flow or annular mist flow is also used.
1173bubble flow, churn flow, flow structure, froth flow, mist
1174None
1175None
1176--
1177mud pit
11781.n. [Drilling Fluids]
1179A large tank that holds drilling fluid on the rig or at a mud-mixing plant. For land rigs, most mud pits are rectangular steel construction, with partitions that hold about 200 barrels each. They are set in series for the active mud system. On most offshore rigs, pits are constructed into the drilling vessel and are larger, holding up to 1000 barrels. Circular pits are used at mixing plants and on some drilling rigs to improve mixing efficiency and reduce dead spots that allow settling. Earthen mud pits were the earliest type of mud pit, but environmental protection concern has led to less frequent use of open pits in the ground. Today, earthen pits are used only to store used or waste mud and cuttings prior to disposal and remediation of the site of the pit.
1180gunning the pits, prehydrated bentonite
1181None
1182None
1183--
1184manifold
11851.n. [Well Completions, Well Workover and Intervention]
1186An arrangement of piping or valves designed to control, distribute and typically monitor fluid flow. Manifolds are often configured for specific functions, such as a choke manifold used in well control operations, a frac manifold for directing treatment fluid, and a squeeze manifold used in squeeze-cementing work. In each case, the functional requirements of the operation have been addressed in the configuration of the manifold and the degree of control and instrumentation required.
1187None
1188None
1189None
1190--
1191manifold
11922.n. [Production]
1193A common pipe or chamber having several lateral outlets.
1194None
1195None
1196None
1197--
1198microbial enhanced oil recovery
11991.n. [Enhanced Oil Recovery]
1200An enhanced recovery process in which microorganisms are used in a reservoir to improve oil recovery. The microorganism can either be injected into the reservoir, or the population of an existing microorganism in the reservoir can be enhanced by injection of nutrients preferred by that microorganism. The microorganisms improve oil recovery by various means: (1) by releasing gases and increasing the pressure of the reservoir; (2) by breaking the heavier molecules into smaller chain components, resulting in the reduction of viscosity of oil; and 3) by producing natural surfactants that can improve oil flow by altering the interfacial properties of the system comprising the crude oil, brine and rock.
1201None
1202None
1203None
1204--
1205mixed metal hydroxide
12061.n. [Drilling Fluids]
1207mixed-metal hydroxide 1.n.[Drilling Fluids] ID: 2102 A compound containing hydroxide anions in association with two or more metal cations. MMH particles are extremely small and carry multiple positive charges. They can associate with bentonite to form a strong complex that exhibits highly shear-thinning properties, with high and fragile gel strengths, high yield point (YP), and low plastic viscosity (PV). MMH is described as a mixed-metal layered hydroxide (MMLH). In the crystal layers, Al+3 , Mg+2 and OH- ions reside, but due to symmetry considerations, there is not enough room for sufficient OH- ions to electrically offset the charges of the two cations. Therefore, a net positive charge exists on the crystal surfaces. Exchangeable anions sit on the positive surface (much the same as cations sit on negative clay surfaces). MMH muds are used as nondamaging drilling fluids, metal-reaming fluids (to carry out metal cuttings) and for wellbore shale control. Being cationic, MMH mud is sensitive to anionic deflocculants and small anionic polymers, such as polyphosphates, lignosulfonate or lignite.Reference:Burba JL III and Crabb CR: "Laboratory and Field Evaluation of Novel Inorganic Drilling Fluid Additive," paper IADC/SPE 17198, presented at the IADC/SPE Drilling Conference, Dallas, Texas, USA, February 28-March 2, 1988.Fraser L and Enriquez F: "Mixed-Metal Hydroxides Fluid Research Widens Applications," Petroleum Engineer International 64, no. 6 (June 1992): 43-46.
1208None
1209None
1210mixed-metal hydroxide
1211--
1212mud program
12131.n. [Drilling Fluids]
1214A formal plan developed for a specific well with predictions and requirements at various intervals of the wellbore depth. The mud program gives details on mud type, composition, density, rheology, filtration and other property requirements and general and specific maintenance needs. Mud densities are especially important because they must fit with the casing design program and rock mechanics required in openhole to ensure wellbore pressures are properly controlled as the well is drilled deeper.
1215filtration, hydrostatic pressure, mud weight, rheology
1216None
1217None
1218--
1219marine flooding surface
12201.n. [Reservoir Characterization]
1221Sometimes abbreviated to flooding surface, a surface exhibiting evidence of an abrupt increase in water depth, separating younger from older strata. The surface may also display evidence of minor submarineerosion. It forms in response to an increase in water depth and typically bounds parasequences. Insequencestratigraphic terminology, it replaces the older, more generic term "trangressive surface," although it is not a strict equivalent.
1222maximum flooding surface, parasequence, sequence, stratigraphy, transgressive surface
1223None
1224None
1225--
1226microcylindrical log
12271.n. [Formation Evaluation]
1228An electrode device with small spacings from which the current flow, and hence the measurement, is focused a short distance into the formation. The microcylindrical log measures the resistivity of the flushed zone with minimum influence from the mudcake or the undisturbed zone. The electrodes are mounted on a pad that is pressed against the borehole wall. The current is focused both parallel and perpendicular to the tool axis. Three measurements are made, each with a different depth of investigation. These measurements are combined to solve for the mudcake and flushed-zone resistivity.
1229electrode resistivity, flushed zone, microresistivity
1230None
1231None
1232--
1233mixed metal hydroxide
12341.n. [Drilling Fluids]
1235A compound containing hydroxide anions in association with two or more metal cations. MMH particles are extremely small and carry multiple positive charges. They can associate with bentonite to form a strong complex that exhibits highly shear-thinning properties, with high and fragile gel strengths, high yield point (YP), and low plastic viscosity (PV). MMH is described as a mixed-metal layered hydroxide (MMLH). In the crystal layers, Al+3 , Mg+2 and OH- ions reside, but due to symmetry considerations, there is not enough room for sufficient OH- ions to electrically offset the charges of the two cations. Therefore, a net positive charge exists on the crystal surfaces. Exchangeable anions sit on the positive surface (much the same as cations sit on negative clay surfaces). MMH muds are used as nondamaging drilling fluids, metal-reaming fluids (to carry out metal cuttings) and for wellbore shale control. Being cationic, MMH mud is sensitive to anionic deflocculants and small anionic polymers, such as polyphosphates, lignosulfonate or lignite.Reference:Burba JL III and Crabb CR: "Laboratory and Field Evaluation of Novel Inorganic Drilling Fluid Additive," paper IADC/SPE 17198, presented at the IADC/SPE Drilling Conference, Dallas, Texas, USA, February 28-March 2, 1988.Fraser L and Enriquez F: "Mixed-Metal Hydroxides Fluid Research Widens Applications," Petroleum Engineer International 64, no. 6 (June 1992): 43-46.
1236anion, cation, cation-exchange capacity, deflocculant, gel strength, thixotropy
1237None
1238MMH
1239--
1240mud pulse telemetry
12411.n. [Drilling]
1242A method of transmitting LWD and MWD data acquired downhole to the surface, using pressure pulses in the mud system. The measurements are usually converted into an amplitude- or frequency-modulated pattern of mud pulses. The same telemetry system is used to transmit commands from the surface.
1243logging while drilling, measurements-while-drilling, survey, telemetry
1244None
1245None
1246--
1247marker bed
12481.n. [Geophysics]
1249A widespread distinctive rock unit that can be correlated readily over a large area. The most useful marker beds tend to form rapidly, such as during volcanic or geologically instantaneous depositional events, and have unusual seismic, magnetic, electrical or other physical properties that aid geological or geophysical interpretation. Coal beds and volcanic ash falls are examples of marker beds.
1250correlate, igneous, pick
1251None
1252None
1253--
1254microemulsion
12551.n. [Enhanced Oil Recovery]
1256A thermodynamically stable emulsion consisting of a mixture of oil, water and surfactant. In contrast to a simple emulsion formed under shear, a microemulsion is a minimum energy state. It does not require an input of energy into the system to form; instead, it forms spontaneously. Depending on the structure of the surfactant and the presence or absence of cosurfactant, an oil-in-water system (Winsor Type I), a water-in-oil system (Winsor Type II) or a bicontinuous system (Winsor Type III) may form. Various structures of micelles and reverse micelles are possible, ranging from spherical through cylindrical to lamellar. A typical microemulsion will have micelle diameters in the range of 3 to 20 nm.
1257emulsion, micelle, Winsor phase behavior
1258None
1259None
1260--
1261mmh
12621.n. [Drilling Fluids]
1263A compound containing hydroxide anions in association with two or more metal cations. MMH particles are extremely small and carry multiple positive charges. They can associate with bentonite to form a strong complex that exhibits highly shear-thinning properties, with high and fragile gel strengths, high yield point (YP), and low plastic viscosity (PV). MMH is described as a mixed-metal layered hydroxide (MMLH). In the crystal layers, Al+3 , Mg+2 and OH- ions reside, but due to symmetry considerations, there is not enough room for sufficient OH- ions to electrically offset the charges of the two cations. Therefore, a net positive charge exists on the crystal surfaces. Exchangeable anions sit on the positive surface (much the same as cations sit on negative clay surfaces). MMH muds are used as nondamaging drilling fluids, metal-reaming fluids (to carry out metal cuttings) and for wellbore shale control. Being cationic, MMH mud is sensitive to anionic deflocculants and small anionic polymers, such as polyphosphates, lignosulfonate or lignite.Reference:Burba JL III and Crabb CR: "Laboratory and Field Evaluation of Novel Inorganic Drilling Fluid Additive," paper IADC/SPE 17198, presented at the IADC/SPE Drilling Conference, Dallas, Texas, USA, February 28-March 2, 1988.Fraser L and Enriquez F: "Mixed-Metal Hydroxides Fluid Research Widens Applications," Petroleum Engineer International 64, no. 6 (June 1992): 43-46.
1264None
1265None
1266mixed-metal hydroxide
1267--
1268mud report
12691.n. [Drilling Fluids]
1270The report sheets filled out by the mud engineer at the wellsite on a daily basis. The mud report supplies results of tests performed several times per day as well as details about mud product usage, inventory, recommendations and other pertinent information. Multiple-copy forms in a format approved by the API, which are provided by the mud service company, are the traditional type of mud report. Today, mud reports are more likely to be computerized and transmitted electronically.
1271high-gravity solids, low-gravity solids
1272None
1273None
1274--
1275marl
12761.n. [Geology]
1277A sedimentary rock containing a mix of clay and calcium carbonate. Compositionally, marls comprise 35% to 65% clay and 65% to 35% calcium carbonate. Thus, marl encompasses a spectrum that ranges from calcareous shale to muddy or shaly limestone.
1278None
1279None
1280None
1281--
1282microgel
12831.n. [Drilling Fluids]
1284A small fish eye, typically invisible, but which can nevertheless cause formation damage by polymer plugging of pore throats. Microgels may be formed by adding polymer too quickly when viscosifying a completion brine.
1285fish eye, pore throat
1286None
1287None
1288--
1289mmscf
12901.n. [Production Testing]
1291Abbreviation for million standard cubic feet, a common measure for volume of gas. Standard conditions are normally set at 60oF and 14.7 psia.
1292million standard cubic feet
1293None
1294None
1295--
1296mud return line
12971.n. [Drilling]
1298Also known as flowline, the large-diameter metal pipe that connects the bell nipple under the rotary table to the possum belly at the mud tanks. The flowline is simply an inclined, gravity-flow conduit to direct mud coming out the top of the wellbore to the mud surface-treating equipment. When drilling certain highly reactive clays, called "gumbo," the flowline may become plugged and require considerable effort by the rig crew to keep it open and flowing. In addition, the flowline is usually fitted with a crude paddle-type flow-measuring device commonly called a "flow show" that may give the driller the first indication that the well is flowing.
1299bell nipple, circulation system, gumbo, rotary table
1300None
1301flowline
1302--
1303marsh funnel
13041.n. [Drilling Fluids]
1305A conical-shaped funnel, fitted with a small-bore tube on the bottom end through which mud flows under a gravity head. A screen over the top removes large particles that might plug the tube. In the test standardized by API for evaluating water-base and oil-base muds, the funnel viscosity measurement is the time (in seconds) required for one quart of mud to flow out of a Marsh funnel into a graduated mud cup. Funnel viscosity is reported in seconds (for a quart). Water exits the funnel in about 26 seconds. This test was one of the earliest mud measurements for field use. Simple, quick and fool-proof, it still serves as a useful indicator of change in the mud by comparing mud-in and mud-out sample funnel viscosities. Hallan N. Marsh of Los Angeles published the design and use of his funnel viscometer in 1931, and it is worth the time to read the detailed, often humorous, discussion that followed. Mr. Marsh was a forward thinking mud technologist in his day, as can be seen from the following words from his 1931 AIME paper:"The subject of mud sounds so simple, uninteresting and unimportant that it has failed to receive the attention that it deserves, at least as applied to the drilling of oil wells. As a matter of fact, it is one of the most complicated, technical, important and interesting subjects in connection with rotary drilling." Mr. Marsh was quoted by someone who knew him as saying (paraphrased), "Of all the things I have done in mud technology, I am remembered for inventing this d*** funnel."Reference:Marsh H: "Properties and Treatment of Rotary Mud," Petroleum Development and Technology, Transactions of the AIME (1931): 234-251.
1306derrickman, funnel viscosity, gel strength, Marsh funnel viscosity, viscosity, viscosity and gel-strength test
1307None
1308None
1309--
1310microlaterolog
13111.n. [Formation Evaluation]
1312An electrode device with small spacings from which the current flow, and hence the measurement, is focused a short distance into the formation. Introduced in 1953, the microlaterolog measures the resistivity of the flushed zone with minimum influence from the mudcake or the undisturbed zone. The central current emitting electrode (A0) is surrounded by a guard electrode that emits sufficient current to focus the current from A0 a certain distance into the formation. The electrodes are mounted on a pad that is pressed against the borehole wall. In a typical tool design, 90% of the signal comes from within 3 in. [7.6 cm] of the pad, ensuring that the undisturbed zone rarely has an effect.
1313electrode resistivity, flushed zone, microresistivity
1314None
1315None
1316--
1317mobility
13181.n. [Well Testing, Enhanced Oil Recovery]
1319The ratio of effective permeability to phase viscosity. The overall mobility is a sum of the individual phase viscosities. Well productivity is directly proportional to the product of the mobility and the layer thickness product.
1320effective permeability, viscosity
1321None
1322None
1323--
1324mud tracer
13251.n. [Drilling Fluids]
1326A type of nonreactive, easily differentiated material placed in a small portion of a circulating mud system at a certain time to be identified when it later returns to the surface from downhole. Mud tracers are used to determine mud cycle time (circulation time). Dyes, paints, beans, oats, chips, glitter or any material that will follow the mud and not be lost or destroyed can be used as a tracer. Care must be taken to use materials that do not dissolve, disperse or plug the bit or downhole motor. Mud tracers are distinct from mud-filtrate tracers.
1327cycle time, filtrate tracer, lag time, tracer
1328None
1329None
1330--
1331massif
13321.n. [Geology]
1333A block of rock that forms a structural or topographic feature, such as a block of igneous of metamorphic rock within an area of mountain building, or orogeny. A massif can be as large as a mountain and is typically more rigid than the rocks that surround it.
1334igneous, metamorphic, orogeny
1335None
1336None
1337--
1338microlog
13391.n. [Formation Evaluation]
1340An unfocused electrode device with small spacings, mounted on a pad and pressed against the borehole wall. The typical microlog has one current-emitting electrode and two measure electrodes in line above it, one at 1 in. [2.5 cm], the other at 2 in. [5 cm]. The potential at the 2-in. electrode gives a 2-in. micronormal log. The difference in potential between the two measure electrodes gives a 1-in. x 1-in. microinverse log. The micronormal reads deeper than the microinverse.Introduced in 1948, the microlog is used to detect permeable zones across which a mudcake has formed. Since the mudcake is usually less resistive than the invaded zone, the microinverse will read less than the micronormal opposite permeable zones. If the resistivity and thickness of the mudcake are known, it is possible to estimate the resistivity of the flushed zone. The log is usually presented on a linear scale, chosen to emphasize the lower readings often seen opposite permeable zones with mudcake.
1341lateral, microresistivity, normal
1342None
1343None
1344--
1345mobility buffer
13461.n. [Enhanced Oil Recovery]
1347In chemical flooding, a fluid stage, normally water thickened with a polymer, pumped between the micellar or alkaline chemical solution and the final water injection.Mobility buffers are prepared with polyacrylamides or polysaccharides and are frequently employed in micellar-polymer flooding operations because they improve sweep efficiency, which increases oil production. The high viscosity of the mobility buffer aids in the displacement of chemicals into the reservoir and also minimizes the channeling of the final water injection into the chemical solution or into the resulting oil bank.
1348polyacrylamide, polysaccharide
1349None
1350None
1351--
1352mud up
13531.vb. [Drilling Fluids]
1354To add commercial materials to convert water or a water-clayslurryinto a mud. Mudding up is usually done after drilling a well to a certain depth with relatively inexpensive spud mud or other native-clay mud, or with water or air. By delaying the use ofdrilling fluid, operators can save money in the initial stages of drilling a well.
1355mud, mud additive, mudding up, native-solids mud, spud mud
1356None
1357None
1358--
1359mast
13601.n. [Drilling]
1361The structure used to support the crown block and the drillstring. Masts are usually rectangular or trapezoidal in shape and offer a very good stiffness, important to land rigs whose mast is laid down when the rig is moved. They suffer from being heavier than conventional derricks and consequently are not usually found in offshore environments, where weight is more of a concern than in land operations.
1362crown block, derrick, escape line, gooseneck, vee-door
1363None
1364None
1365--
1366micropaleontology
13671.n. [Geology]
1368The study of microfossils too small to be seen without the use of a microscope. Marine microfossils such as foraminifera are important for stratigraphic correlation.
1369biostratigraphy, paleontology, palynology
1370None
1371None
1372--
1373modified isochronal test
13741.n. [Well Testing]
1375A multirate test designed as a series of drawdown and buildup sequences at different drawdown flow rates, with each drawdown and buildup of the same duration. The purpose of the test is to determine well deliverability, and this type of test is most commonly done in gas wells.
1376isochronal test
1377None
1378None
1379--
1380modified isochronal test
13812.n. [Production Testing]
1382A type of deliverability test conducted in gas wells to generate a stabilized gas deliverability curve (IPR). This test overcomes the limitation of the isochronal test, which requires long shut-in times to reach the <a href="Display.cfm?Term=average%20reservoir%20pressure">average <a href="Display.cfm?Term=reservoir">reservoir pressure.In the modified isochronal test, the shut-in periods are of equal duration, as are the flowing periods. The final shut-in pressure before the beginning of the new flow is used as an approximation of the average reservoir pressure. The same procedure is typically repeated four times. A stabilized point (pseudosteady state) is usually obtained at the end of the test.Modified isochronal tests are commonly used in gas wells, because they require less time and money to produce results comparable to the isochronal test.
1383None
1384None
1385None
1386--
1387mud weight
13881.n. [Drilling Fluids]
1389The mass per unit volume of a drilling fluid, synonymous with mud density. Weight is reported in lbm/gal (also known as ppg), kg/m3 or g/cm3 (also called specific gravity or SG), lb/ft3 or in hydrostatic gradient, lb/in2/ft (psi/ft) or pptf (psi/1000 ft). Mud weight controls hydrostatic pressure in a wellbore and prevents unwanted flow into the well. The weight of the mud also prevents collapse of casing and the openhole. Excessive mud weight can cause lost circulation by propagating, and then filling, fractures in the rock. Mud weight (density) test procedures using a mud balance have been standardized and published by the API.
1390bland coring fluid, calcium bromide, cesium acetate, cesium formate, equivalent circulating density, formate, gunning the pits, high-gravity solids, kill-weight fluid, kilogram per cubic meter, mud, mud balance, mud program, pressurized mud balance, PVT, sag, slug, weighting material
1391mud density
1392None
1393--
1394master valve
13951.n. [Well Completions]
1396A valve located on the Christmas tree that controls all flow from the wellbore. A correctly functioning master valve is so important that two master valves are fitted to most Christmas trees. The upper master valve is used on a routine basis, with the lower master valve providing backup or contingency function in the event that the normal service valve is leaking and needs replacement.
1397None
1398None
1399None
1400--
1401microporosity
14021.n. [Formation Evaluation]
1403That part of the pore space that has a characteristic dimension less than 1 micron. In general, this includes not only very small pores but also the porosity associated with surface roughness. The water in this pore space is part of the capillary-bound water and the small-pore water. Water in micropores is not expected to flow on production. The term is also defined as porosity that cannot be seen at magnifications less than 50x.
1404effective porosity, small-pore water, total porosity
1405None
1406None
1407--
1408modulus of rigidity
14091.n. [Geophysics]
1410Another term for shear modulus, an elastic constant for the ratio of shear stress to shear strain. The shear modulus is one of the Lamé constants. It can be expressed mathematically as follows:μ = τ / γ = (ΔF/A) / (ΔL/L),whereμ = Shear modulusτ = Shear stress = ΔF/AΔF = Increment of shear forceA = Area acted on by the shear forceγ = Shear strain = ΔL/LΔL = Increment of transverse displacement parallel to AL = Original length.
1411elastic constants, Lamé constant
1412None
1413shear modulus
1414--
1415mud aging cell
14161.n. [Drilling Fluids]
1417A cylindrical vessel in which a mud sample can be heated under pressure. Cells, often called bombs, are routinely used for static-aging and hot-roll aging of mud samples. Cells are usually made of metal or metal alloy, such as stainless steel or aluminum bronze, and have open tops. Caps should be fitted with a valve so that gas pressure can be applied and then released before opening the cell. Common sizes are 260 and 500 cm3, to accommodate half- and one-barrel equivalent volumes, plus space for thermal expansion. Glass or plastic jars can be used judiciously when pressure is nil and temperature is limited to below about 150°F [66°C].
1418barrel equivalent, bomb, bottoms-up mud sample, mud oven, pilot test, rolling-aging test, shear-strength measurement test, static-aging test, temperature stability
1419None
1420mud cell
1421--
1422material safety data sheet
14231.n. [Drilling Fluids]
1424A specific document that shows important physical and chemical characteristics of a chemical or product to alert a user, transporter or other interested party to potential safety hazards that may be associated with the material. The MSDS also contains treatments for exposure or ingestion as well as the type of equipment needed for safe handling. An MSDS is a legal requirement in most countries for all aspects of commerce involving chemicals.
1425None
1426None
1427MSDS
1428--
1429microresistivity
14301.n. [Formation Evaluation]
1431Related to a log of the resistivity of the flushed zone recorded by a wireline electrode device. The device is mounted on a pad and pressed against the borehole wall. Several designs exist, for example microlog, microlaterolog, proximity log, microspherical log and microcylindrical log. The microlog, being unfocused, is a more qualitative measurement.The other measurements are focused. They try to minimize the effect of mudcake and rugose hole, while reading as short a distance as possible into the formation, to remain unaffected by the undisturbed zone. They are usually combined with a laterolog or induction log to correct the latter for the effects of invasion and for saturation determination in quick-look ratio methods. The logs are presented on a logarithmic scale from, for example 0.2 to 2000 ohm-m.
1432electrode resistivity, flushed zone, microcylindrical log, microspherical log, proximity log, spherical focusing, undisturbed zone
1433None
1434None
1435--
1436moho
14371.n. [Geology]
1438The boundary between the crust and the mantle of the Earth, which varies from approximately 5 km [3 miles] under the midoceanic ridges to 75 km [46 miles] deep under the continents. This boundary, commonly called "the Moho," was recognized in 1909 by Croatian seismologist Andrija Mohorovicic on the basis of its abruptly higher compressional wave (P-wave) velocity.
1439None
1440None
1441Mohorovicic discontinuity
1442--
1443mudcake
14441.n. [Drilling Fluids, Formation Evaluation]
1445The residue deposited on a permeable medium when a slurry, such as a drilling fluid, is forced against the medium under a pressure. Filtrate is the liquid that passes through the medium, leaving the cake on the medium. Drilling muds are tested to determine filtration rate and filter-cake properties. Cake properties such as cake thickness, toughness, slickness and permeability are important because the cake that forms on permeable zones in the wellbore can cause stuck pipe and other drilling problems. Reduced oil and gas production can result from reservoir damage when a poor filter cake allows deep filtrate invasion. A certain degree of cake buildup is desirable to isolate formations from drilling fluids. In openhole completions in high-angle or horizontal holes, the formation of an external filter cake is preferable to a cake that forms partly inside the formation. The latter has a higher potential for formation damage.
1446deflocculated mud, drilling fluid, dynamic filtration, filter-cake quality, filter-cake thickness, filtrate, filtrate volume, openhole completion, relative filtrate volume, resin, static filtration
1447filter cake
1448None
1449--
1450matrix acidizing
14511.n. [Well Workover and Intervention, Well Completions]
1452The treatment of a reservoir formation with a stimulation fluid containing a reactive acid. In sandstone formations, the acid reacts with the soluble substances in the formation matrix to enlarge the pore spaces. In carbonate formations, the acid dissolves the entire formation matrix. In each case, the matrix acidizing treatment improves the formation permeability to enable enhanced production of reservoir fluids. Matrix acidizing operations are ideally performed at high rate, but at treatment pressures below the fracture pressure of the formation. This enables the acid to penetrate the formation and extend the depth of treatment while avoiding damage to the reservoir formation.
1453matrix, stimulation fluid
1454acid job, acid stimulation, acidize, acidizing, matrix stimulation
1455None
1456--
1457microseismic monitoring
14581.n. [Well Completions, Shale Gas]
1459A technique to track the propagation of a hydraulic fracture as it advances through a formation. Microseisms are detected, located, and displayed in time for scientists and engineers to approximate the location and propagation of the hydraulic fracture. Software provides modeling, survey design, microseismic detection and location, uncertainty analysis, data integration, and visualization for interpretation. Computer imagery is used to monitor the activity in 3D space relative to the location of the fracturing treatment. The monitored activities are animated to show progressive fracture growth and the subsurface response to pumping variations. When displayed in real time, the microseismic activity allows one to make changes to the stimulation design to ensure optimal reservoir contact. Also known as hydraulic fracture monitoring, this technique delivers information about the effectiveness of the stimulation of a reservoir that can be used to enhance reservoirdevelopmentinshalegas completions.
1460None
1461None
1462None
1463--
1464mohorovicic discontinuity
14651.n. [Geology]
1466The boundary between the crust and the mantle of the Earth, which varies from approximately 5 km [3 miles] under the midoceanic ridges to 75 km [46 miles] deep under the continents. This boundary, commonly called "the Moho," was recognized in 1909 by Croatian seismologist Andrija Mohorovicic on the basis of its abruptly higher compressional wave (P-wave) velocity.
1467crust, mantle, midoceanic ridge
1468None
1469Moho
1470--
1471mudding up
14721.n. [Drilling Fluids]
1473The act of adding commercial materials to convert water or a water-clay slurry into a mud. Mudding up is usually done after drilling a well to a certain depth with relatively inexpensive spud mud or other native-clay mud, or with water or air. By delaying the use of drilling fluid, operators can save money in the initial stages of drilling a well.
1474mud, mud additive, mud up, native-solids mud, spud mud
1475None
1476None
1477--
1478matrix stimulation
14791.n. [Well Workover and Intervention, Well Completions]
1480A treatment designed to treat the near-wellbore reservoir formation rather than other areas of the production conduit, such as the casing across the production interval, production tubulars or the perforations. Matrix stimulation treatments include acid, solvent and chemical treatments to improve the permeability of the near-wellbore formation, enhancing the productivity of a well.Matrix stimulation is a process of injecting a fluid into the formation, either an acid or solvent at pressures below the fracturing pressure, to improve the production or injection flow capacity of a well. The goal of a matrix treatment is different in sandstones than in carbonates. In sandstones, matrix treatments restore or improve the natural formation permeability around the wellbore by removing formation damage, by dissolving material plugging the pores or by enlarging the pore spaces. In carbonates, matrix stimulation creates new, highly conductive channels (wormholes) that bypass damage.Because of these differences, the selection criteria for the treating fluid are also distinct. For sandstone treatments, knowledge of the extent, type of damage, location, origin, reservoir mineralogy (petrographic study) and compatibility of the treating fluid with the formation are especially important. In carbonate treatments, reservoir temperature, pumping rate and fluid type become more significant because these parameters directly affect the reactivity of the treating fluid with the reservoir rock.A sandstone matrix stimulation treatment is generally composed of a hydrochloric acid [HCl] preflush, a main treating fluid (HCl-HF mixtures) and an overflush (weak acid solution or brine). The treating fluid is maintained under pressure inside the reservoir for a period of time, after which the well is swabbed and returned to production. In carbonate reservoirs, HCl is the most common fluid used. Organic acids such as formic and acetic acid are used in either sandstone or carbonate acidizing, mainly in retarded-acid systems or in high-temperature applications.Matrix stimulation is also called matrix treatment or matrix acidizing.
1481acid job, acid stimulation, acidize, acidizing, critical matrix, fracture acidizing, matrix, matrix acidizing
1482None
1483None
1484--
1485microspherical log
14861.n. [Formation Evaluation]
1487An electrode device with small spacings from which the current flow, and hence the measurement, is focused a short distance into the formation. The microspherical log measures the resistivity of the flushed zone with minimum influence from the mudcake or the undisturbed zone. The principle of spherical focusing is used. The electrodes are mounted on a pad that is pressed against the borehole wall. In a typical tool design, 90% of the signal comes from within 3 in. [7.6 cm] of the pad, ensuring that the undisturbed zone rarely has an effect.
1488electrode resistivity, microresistivity
1489None
1490None
1491--
1492monkey board
14931.n. [Drilling]
1494The small platform that the derrickman stands on when tripping pipe.
1495None
1496None
1497monkeyboard
1498--
1499mud in sample
15001.n. [Drilling Fluids]
1501A mud sample taken from the suction pit (the last pit in the flow series) just before the mud goes into the pump and down the wellbore. The in sample is also called the suction-pit sample, or "mud in" on a drilling fluid report. This mud has been treated and properly weighted and is in good condition to encounter downhole pressures, temperatures and contamination. Comparisons are made between properties of this mud-in sample and the "out" or mud-out sample taken at surface prior to solids removal.
1502bottoms-up mud sample, cycle time, flowline mud sample, lag time, mud in, pilot test
1503None
1504None
1505--
1506maturation
15071.n. [Shale Gas]
1508The process of a source rock becoming capable of generating oil or gas when exposed to appropriate pressures and temperatures. As a source rock begins to mature, it generates hydrocarbons. As an oil-prone source rock matures, the generation of heavy oils is succeeded by medium and light oils and condensates. Above a temperature of approximately 100&amp;degC [212&amp;degF], only dry gas is generated, and incipient metamorphism is imminent. The maturity of a source rock reflects the ambient pressure and temperature as well as the duration of conditions favorable for hydrocarbon generation. Understanding maturation is especially important in shale reservoirs because of the shales dual role as source rock and reservoir rock.
1509None
1510None
1511None
1512--
1513midoceanic ridge
15141.n. [Geology]
1515The mountainous, linear axis of ocean basins along which rifting occurs and new oceanic crust forms as magma wells up and solidifies. The most prominent midoceanic ridges are those of the Atlantic and Indian Oceans. The new crust is made of mafic igneous rock called basalt, commonly referred to as midocean ridge basalt, or MORB, whose composition reflects that of the deeper mantle of the Earth. The presence of the spreading plate boundaries of the midoceanic ridges; their symmetrically spreading, successively older crust outward from the ridge; and the lack of oceanic crust older than approximately 200 Ma support the theory of plate tectonics and the recycling of oceanic crust through the process of subduction.
1516crust, geomagnetic polarity reversal, geomagnetic polarity time scale, igneous, mafic, mantle, Mohorovicic discontinuity, plate tectonics, rift, subduction
1517None
1518None
1519--
1520monkeyboard
15211.n. [Drilling]
1522The small platform that the derrickman stands on when tripping pipe.
1523derrickman, fingerboard, tripping pipe
1524None
1525None
1526--
1527mud out sample
15281.n. [Drilling Fluids]
1529A mud sample taken after it has passed from the flowline and through the shale shaker screens to remove large cuttings. The out sample is also called the shale shaker sample. This mud has experienced the downhole pressures, temperatures and contamination that cause degradation. It is evaluated for needed treatments and compared, on a lagged time basis, with the corresponding "in" or mud-in sample.
1530bottoms-up mud sample, cycle time, lag time, mud out, pilot test
1531None
1532flowline mud sample, flowline sample
1533--
1534maximum recorded temperature
15351.n. [Formation Evaluation]
1536The highest temperature recorded on a logging run. It is usually taken to be the bottomhole temperature for use in log interpretation. However, on the first logging run or runs after circulation, the mud may be hottest some distance above the bottom of the hole.
1537None
1538None
1539None
1540--
1541migrate
15421.vb. [Geology]
1543For hydrocarbons to move from theirsourceinto reservoir rocks.The movement of newly generated hydrocarbons out of their source rock is primary migration, also called expulsion. The further movement of the hydrocarbons into reservoir rock in a hydrocarbon trap or other area of accumulation is secondary migration. Migration typically occurs from a structurally low area to a higher area because of the relative buoyancy of hydrocarbons in comparison to the surrounding rock. Migration can be local or can occur along distances of hundreds of kilometers in large sedimentary basins, and is critical to the formation of a viable petroleum system.
1544accumulation, basin, cap rock, critical moment, generation, petroleum system, preservation, primary migration, prospect, reservoir, seal, secondary migration, sedimentary basin, source rock, spill point, trap
1545None
1546None
1547--
1548migrate
15492.vb. [Geophysics]
1550To execute a step inseismic processingin which reflections in seismic data are moved to their correct locations in x-y-time space of seismic data. Migration improves seismic interpretation and mapping because the locations of geological structures, especially faults, are more accurate in migrated seismic data. Proper migration collapses diffractions from secondary sources such as reflector terminations against faults and corrects bow ties to form synclines. There are numerous methods of migration, such as dip moveout (DMO), frequency domain, ray-trace and wave-equation migration.
1551bow tie, depth migration, depth section, diffraction, dip moveout, frequency domain, Kirchhoff migration, processing, reflection, resolution, shotpoint, sideswipe, smile, three-dimensional seismic data, time migration, two-way traveltime, velocity analysis
1552None
1553None
1554--
1555monopole
15561.adj. [Formation Evaluation]
1557Describing a type of acoustic transducer that emits or receives energy in all directions. Monopole transducers are used in standard sonic logs, and also inarray-sonic logs to record shear and Stoneley waves.
1558acoustic mode, dipole, S-wave, sonic measurement, Stoneley wave
1559None
1560None
1561--
1562mudrock
15631.n. [Shale Gas]
1564A fine-grained detrital sedimentary rock formed by consolidation of clay- and silt-sized particles. Mudrocks are highly variable in their clay content and are often rich in carbonate material. As a consequence, they are less fissile, or susceptible to splitting along planes, than shales. Mudrocks may include relatively large amounts of organic material compared with other rock types and thus have potential to become rich hydrocarbon source rocks. The typical fine grain size and low permeability, a consequence of the alignment of their platy or flaky grains, allow mudrocks to form good cap rocks for hydrocarbon traps. However, mudrocks are also capable of being reservoir rocks, as evidenced by the many wells drilled into them to produce gas.
1565None
1566None
1567None
1568--
1569maximum treating pressure
15701.n. [Well Workover and Intervention]
1571The surface-pump pressure limit below which a treatment should be performed. The maximum treating pressure is determined to avoid fracturing the formation or damaging completion components. The maximum treating pressure is generally calculated to ensure that the pump-pressure limit equates to downhole and reservoir conditions that are within the design limits of the treatment.
1572None
1573None
1574None
1575--
1576migration
15771.n. [Geology]
1578The movement of hydrocarbons from their source into reservoir rocks. The movement of newly generated hydrocarbons out of their source rock is primary migration, also called expulsion. The further movement of the hydrocarbons into reservoir rock in a hydrocarbon trap or other area of accumulation is secondary migration. Migration typically occurs from a structurally low area to a higher area because of the relative buoyancy of hydrocarbons in comparison to the surrounding rock.Migration can be local or can occur along distances of hundreds of kilometers in large sedimentary basins, and is critical to the formation of a viable petroleum system.
1579accumulation, basin, cap rock, critical moment, generation, migrate, petroleum system, preservation, primary migration, prospect, reservoir, seal, secondary migration, sedimentary basin, source rock, spill point, trap
1580None
1581None
1582--
1583migration
15842.n. [Geophysics]
1585A step in seismic processing in which reflections in seismic data are moved to their correct locations in the x-y-time space of seismic data, including two-way traveltime and position relative to shotpoints. Migration improves seismic interpretation and mapping because the locations of geological structures, especially faults, are more accurate in migrated seismic data. Proper migration collapses diffractions from secondary sources such as reflector terminations against faults and corrects bow ties to form synclines. There are numerous methods of migration, such as dip moveout (DMO), frequency domain, ray-trace and wave-equation migration.
1586bow tie, depth migration, depth section, diffraction, dip moveout, frequency domain, Kirchhoff migration, migrate, processing, reflection, resolution, shotpoint, sideswipe, smile, three-dimensional seismic data, time migration, two-way traveltime, velocity analysis
1587None
1588None
1589--
1590monte carlo risk analysis
15911.n. [Reservoir Characterization]
1592An approach to performing risk analysis on any project with uncertain input data. Generally, numbers are selected from representative input data and then used in iterative, CPU-intensive calculations to find the most likely outcome and the range of probable outcomes. The uncertainty in the output also provides a measure of the validity of the model. The technique is applied to financial investment portfolio and investment risk analysis as well as scientific applications.Monte Carlo analysis methods are used in the oil field to estimate the risks involved in new exploration projects, evaluation of development schemes and evaluation of validity of reservoir models.
1593None
1594None
1595None
1596--
1597multiazimuth towed streamer acquisition
15981.n. [Geophysics]
1599A marine seismic data acquisition method in which a conventional narrow-azimuth towed-streamer configuration is used to acquire data over a survey area in more than one direction. The number of directions is typically three or more. The azimuthal range for a multiazimuth survey is not continuous in azimuth, but is well sampled along the shooting directions.
1600None
1601None
1602None
1603--
1604maxwells equations
16051.n. [Geophysics]
1606A group of four partial differential equations that describe all classical phenomena, involving electric and magnetic fields. James Clerk Maxwell (1831 to 1879), a British physicist, first wrote out this complete set of equations:(1.) ∇·D = ρ(2.) ∇×H = J + (∂D/∂t)(3.) ∇·B = 0(4.) ∇×E = −(∂B/∂t),whereD = electric displacementρ = electric charge densityH = magnetic field strengthJ = electric current densityB = magnetic flux densityE = electric field strength.Equation (1) is equivalent to Coulomb's law, the inverse square attraction of static electric charges. Equation (2) is Ampere's law relating magnetic fields and currents, which was extended by Maxwell to include induction of a magnetic field by a time-varying electric displacement. Equation (3) is Coulomb's law for magnetic flux, expressing the absence of isolated magnetic charges. Equation (4) is Faraday's law of induction, relating an electric field to a time-varying magnetic flux. Maxwell's equations are the starting point for all calculations involving surface or borehole EM methods.
1607electromagnetic method
1608None
1609None
1610--
1611mill
16121.n. [Well Workover and Intervention, Drilling]
1613A tool that grinds metal downhole. A mill is usually used to remove junk in the hole or to grind away all or part of a casing string. In the case of junk, the metal must be broken into smaller pieces to facilitate removal from the wellbore so that drilling can continue. When milling casing, the intent is to cut a window through the side of the casing or to remove a continuous section of the casing so that the wellbore may be deviated from the original well through the window or section removed. Depending on the type of grinding or metal removal required, the shape of the cutting structures of mills varies. Virtually all mills, however, utilize tungsten carbine cutting surfaces.
1614casing string, junk, mill out, packer
1615None
1616None
1617--
1618montmorillonite
16191.n. [Geology]
1620[(1/2Ca,Na)0.7(Al,Mg,Fe)4(Si,Al)8O20(OH)47nH20]A type of smectite clay mineral that tends to swell when exposed to water. Montmorillonite forms through the alteration of silicate minerals in alkaline conditions in basic igneous rocks, such as volcanic ash that can accumulate in the oceans. Montmorillonite is a component of bentonite commonly used in drilling fluids.
1621clay, drilling fluid, mineral, silica, smectite
1622None
1623None
1624--
1625montmorillonite
16262.n. [Drilling Fluids]
1627A hydratable, dispersible clay mineral of the smectite group. Montmorillonite is a three-layer, expanding clay with a large surface area and high cation-exchange capacity. Na+ and Ca+2 are the typical exchangeable cations. Sodium montmorillonite, also called sodium bentonite, is a premium clay mud additive. Natural deposits are found in Wyoming, North Dakota, South Dakota and Utah, USA. Calcium montmorillonite is a low-yield bentonite that is more widely distributed and used in many commercial applications, including drilling fluid.
1628API, clay-water interaction, gumbo, hydration, OCMA, shale, smectite clay
1629None
1630None
1631--
1632multicomponent seismic data
16331.n. [Geophysics]
1634Seismic data acquired in a land, marine, or borehole environment by using more than one geophone or accelerometer. 3C seismic data, a type of multicomponent seismic data, uses three orthogonally oriented geophones or accelerometers. 4C seismic data, another type of multicomponent seismic data, involves the addition of a hydrophone to three orthogonally oriented geophones or accelerometers. 3C multicomponent seismic data is particularly appropriate when the addition of a hydrophone (the basis for 4C seismic data) adds no value to the measurement, for example, on land. This technique allows determination of both the type of wave and its direction of propagation.
1635accelerometer, four-component seismic data, geophone, three-component seismic data
1636None
1637None
1638--
1639md
16401.n. [Drilling]
1641The length of the wellbore, as if determined by a measuring stick. This measurement differs from the true vertical depth of the well in all but vertical wells. Since the wellbore cannot be physically measured from end to end, the lengths of individual joints of drillpipe, drill collars and other drillstring elements are measured with a steel tape measure and added together. Importantly, the pipe is measured while in the derrick or laying on a pipe rack, in an untensioned, unstressed state. When the pipe is screwed together and put into the wellbore, it stretches under its own weight and that of the bottomhole assembly. Although this fact is well established, it is not taken into account when reporting the well depth. Hence, in virtually all cases, the actual wellbore is slightly deeper than the reported depth.
1642None
1643None
1644measured depth
1645--
1646mill out
16471.vb. [Drilling, Well Workover and Intervention]
1648To use amillor similar downhole tool to cut and remove metal downhole. A mill is usually used to remove junk in the hole or to grind away all or part of a casing string. When milling out casing, the intent is to cut a window through the side of the casing or to remove a continuous section of the casing so that the wellbore may be deviated from the original well through the window or section removed. Successful milling operations require appropriate selection of milling tools, fluids and techniques. The mills, or similar cutting tools, must be compatible with thefishor casing materials and wellbore conditions. The circulated fluids should be capable of removing the milled material from the wellbore. Finally, the techniques employed should be appropriate to the anticipated conditions and the likely time required to reach the operation objectives.
1649casing string, junk, milling, packer
1650None
1651None
1652--
1653morning tour
16541.n. [Drilling]
1655The work shift of a drilling crew that starts in the morning. Drilling operations usually occur around the clock because of the cost to rent arig. As a result, there are usually two separate crews working twelve-hour tours to keep the operation going. Some companies prefer three eight-hour tours: the daylight tour starts at daylight or 8 AM; the graveyard tour is the overnight shift or the shift that begins at midnight. (Pronounced "tower" in many areas.)
1656drilling crew, evening tour, graveyard tour, tour
1657None
1658None
1659--
1660multifinger caliper
16611.n. [Production Logging]
1662A device for measuring the diameter of the internal wall of a casing or tubing using multiple arms. By using a large number of arms, or fingers, the caliper can detect small changes in the wall of the pipe. The main purpose of the measurement is to detect deformations, the buildup of scale or metal loss due to corrosion. Typical multifinger calipers have between about 20 and 80 fingers, the larger numbers being necessary in larger pipes.
1663casing-inspection log, electromagnetic caliper, ultrasonic caliper
1664None
1665None
1666--
1667mean
16681.n. [Reservoir Characterization]
1669A mathematical method of finding a central value for a group of data. It is most often referred to as the average but also as the arithmetic mean; it is the sum of all the observed values divided by the number of observations.
1670None
1671arithmetic mean
1672None
1673--
1674mill shoe
16751.n. [Well Workover and Intervention]
1676A downhole tool routinely used in fishing operations to prepare the top and outside surface of a fish, generally to allow an overshot or similar fishing tool to engage cleanly on the fish. In some cases, the outer portion of a fish may be milled out to allow the body and remaining debris to be pushed to the bottom of the wellbore.
1677None
1678washover shoe
1679None
1680--
1681motorman
16821.n. [Drilling]
1683The member of the rig crew responsible for maintenance of the engines. While all members of the rig crew help with major repairs, the motorman does routine preventive maintenance and minor repairs.
1684drilling crew
1685None
1686None
1687--
1688multiphase fluid
16891.n. [Well Completions]
1690A fluid, generally a liquid, comprising more than one phase, such as water- or oil-based liquids, solid material or gas. Multiphase fluids and their behavior are of concern in two main areas, the flow of multiphase fluids and the separation of the various phases at surface.
1691multiphase fluid flow
1692None
1693None
1694--
1695measured depth
16961.n. [Drilling]
1697The length of the wellbore, as if determined by a measuring stick. This measurement differs from the true vertical depth of the well in all but vertical wells. Since the wellbore cannot be physically measured from end to end, the lengths of individual joints of drillpipe, drill collars and other drillstring elements are measured with a steel tape measure and added together. Importantly, the pipe is measured while in the derrick or laying on a pipe rack, in an untensioned, unstressed state. When the pipe is screwed together and put into the wellbore, it stretches under its own weight and that of the bottomhole assembly. Although this fact is well established, it is not taken into account when reporting the well depth. Hence, in virtually all cases, the actual wellbore is slightly deeper than the reported depth.
1698bottomhole assembly, hydrostatic head, pipe rack, true vertical depth
1699None
1700MD
1701--
1702milligrams per kilogram
17031.n. [Drilling Fluids]
1704On the basis of weight, the equivalent of parts per million, usually applied to small amounts of one solid admixed with another solid, such as 100 mg/kg of siderite in barite, the same as 100 ppm.
1705None
1706None
1707None
1708--
1709mousehole
17101.n. [Drilling]
1711An opening in the rig floor near the rotary table, but between the rotary table and the vee-door, that enables rapid connections while drilling. The mousehole is usually fitted underneath with a length of casing, usually with a bottom. A joint of drillpipe that will be used next in the drilling operation is placed in the mousehole, box end up, by the rig crew at a convenient time (immediately after the previous connection is made). When the bit drills down and the kelly is near the rotary table, another piece of drillpipe must be added for drilling to continue. This next piece of pipe is standing in the mousehole when the kelly is screwed onto it. Then the kelly and the joint of pipe in the mousehole are raised to remove the pipe from the mousehole, the mousehole pipe screwed onto the rest of the drillstring, and the drillstring lowered, rotated, and pumped through to continue drilling. Another piece of pipe is put in the mousehole to await the next connection.
1712box, kelly, make a connection, rathole, rotary table, vee-door
1713None
1714None
1715--
1716multiphase meter
17171.n. [Production Testing]
1718A device that can register individual fluid flow rates of oil and gas when more than one fluid is flowing through a pipeline. A multiphase meter provides accurate readings even when different flow regimes are present in the multiphase flow. When using single-phase meters, the fluid mixture (oil and gas) coming from the wellbore must pass through a fluid-separation stage (separator) prior metering. Otherwise, the readings of the single-phase meters will be inaccurate. Separators are not necessary for multiphase metering, and the meters can support different proportions of gas and oil. Multiphase meters provide the advantage of continuous well monitoring, which is not possible using single-phase meters. Additionally, multiphase meters cost less, weigh less and require less space. Multiphase meters are more common in deepwater operations, where well-intervention operations are often prohibitively expensive.
1719flow regime, multiphase fluid flow, oil and gas separator
1720None
1721None
1722--
1723measurements while drilling
17241.n. [Drilling]
1725The evaluation of physical properties, usually including pressure, temperature and wellbore trajectory in three-dimensional space, while extending a wellbore. MWD is now standard practice in offshore directional wells, where the tool cost is offset by rig time and wellbore stability considerations if other tools are used. The measurements are made downhole, stored in solid-state memory for some time and later transmitted to the surface. Data transmission methods vary from company to company, but usually involve digitally encoding data and transmitting to the surface as pressure pulses in the mud system. These pressures may be positive, negative or continuous sine waves. Some MWD tools have the ability to store the measurements for later retrieval with wireline or when the tool is tripped out of the hole if the data transmission link fails. MWD tools that measure formation parameters (resistivity, porosity, sonic velocity, gamma ray) are referred to as logging-while-drilling (LWD) tools. LWD tools use similar data storage and transmission systems, with some having more solid-state memory to provide higher resolution logs after the tool is tripped out than is possible with the relatively low bandwidth, mud-pulse data transmission system.
1726None
1727None
1728measurements-while-drilling, MWD
1729--
1730milligrams per liter
17311.n. [Drilling Fluids]
1732On a weight per volume basis, the SI unit of concentration, abbreviated mg/L, usually applied to dissolved material in a solution. This unit is used in water analyses and in mud and mud-filtrate analyses. Increasingly, mg/L and ppm are used interchangeably in mud analyses. Actually, mg/L and ppm can only be interchanged when the sample has the exact density of water, which is only approximated by very dilute solutions.
1733API, dissolved solids, epm, ppm
1734None
1735None
1736--
1737moveable hydrocarbons
17381.n. [Formation Evaluation]
1739The volume of hydrocarbons per unit volume of rock that can be moved on production, measured in volume/volume or porosity units. Typically only primary and secondary production methods are considered when estimating moveable hydrocarbons. Moveable hydrocarbons are not necessarily the same as moved hydrocarbons, which are those hydrocarbons that have been moved by invasion.
1740flushed-zone water saturation, moved hydrocarbons, residual oil, water saturation
1741None
1742None
1743--
1744multiphase pump
17451.n. [Production Facilities]
1746A pump that can handle the complete production from a well (oil, natural gas, water and sand, for example) without needing to separate or process the production stream near or at the wellhead. This reduces the cost associated with the surface facilities.Using multiphase pumps allows development of remote locations or previously uneconomical fields. Additionally, since the surface equipment, including separators, heater-treaters, dehydrators and pipes, is reduced, the impact on the environment is also reduced.Multiphase pumps can handle high gas volumes as well as the slugging and different flow regimes associated with multiphase production. Multiphase pumps include twin-screw pumps, piston pumps and helicoaxial pumps.
1747dehydrator, flow regime, heater, multiphase, separator
1748None
1749None
1750--
1751measurements while drilling
17521.n. [Drilling]
1753The evaluation of physical properties, usually including pressure, temperature and wellbore trajectory in three-dimensional space, while extending a wellbore. MWD is now standard practice in offshore directional wells, where the tool cost is offset by rig time and wellbore stability considerations if other tools are used. The measurements are made downhole, stored in solid-state memory for some time and later transmitted to the surface. Data transmission methods vary from company to company, but usually involve digitally encoding data and transmitting to the surface as pressure pulses in the mud system. These pressures may be positive, negative or continuous sine waves. Some MWD tools have the ability to store the measurements for later retrieval with wireline or when the tool is tripped out of the hole if the data transmission link fails. MWD tools that measure formation parameters (resistivity, porosity, sonic velocity, gamma ray) are referred to as logging-while-drilling (LWD) tools. LWD tools use similar data storage and transmission systems, with some having more solid-state memory to provide higher resolution logs after the tool is tripped out than is possible with the relatively low bandwidth, mud-pulse data transmission system.
1754differential pressure, drill collar, logging while drilling, survey, tripping pipe
1755mud pulse telemetry
1756MWD
1757--
1758milling
17591.n. [Well Workover and Intervention, Drilling]
1760The use of a mill or similar downhole tool to cut and remove material from equipment or tools located in the wellbore. Successful milling operations require appropriate selection of milling tools, fluids and techniques. The mills, or similar cutting tools, must be compatible with the fish materials and wellbore conditions. The circulated fluids should be capable of removing the milled material from the wellbore. Finally, the techniques employed should be appropriate to the anticipated conditions and the likely time required to reach the operation objectives.
1761casing string, junk, mill out, packer
1762None
1763None
1764--
1765mrs
17661.n. [Geology]
1767Abbreviation for magnetic reversal sequence, the periodic switching of the magnetic north and south poles of the Earth throughout time, probably as a result of movement of fluid within the Earth's core. The onset and duration of the many episodes of reversed polarity have been documented by examining the polarity of magnetic minerals within rocks of different ages from around the world, particularly in basalts or igneous rocks of the oceanic crust. Oceanic basalts record the Earth's magnetic field as they solidify from molten lava symmetrically on each side of the midoceanic ridges. These data have been compiled to create a time scale known as the geomagnetic polarity time scale (GPTS). In the oil field, borehole recordings allow direct correlation to GPTS and well-to-well correlations.
1768geochronology, geologic time scale, geomagnetic polarity time scale, midoceanic ridge, natural remanent magnetism
1769None
1770None
1771--
1772multiple rate tests
17731.n. [Well Testing]
1774Tests conducted at a series of different flow rates for the purpose of determining well deliverability, typically in gas wells where non-Darcy flow near the well results in a rate-dependent skin effect. Multiple-rate tests are sometimes required by regulatory bodies.
1775gas-well deliverability, non-Darcy flow, skin effect
1776None
1777multiple-rate tests
1778--
1779measuring tank
17801.n. [Production Testing]
1781A calibrated tank that automatically measures the liquid volume passing through it. Measuring tanks are also called metering tanks or dump tanks.
1782None
1783None
1784None
1785--
1786million standard cubic feet
17871.n. [Production Testing]
1788A common measure for gas volume. Standard conditions are normally set at 60oF and 14.7 psia, abbreviated MMscf.
1789None
1790None
1791None
1792--
1793mscfd
17941.n. [Production Testing]
1795Abbreviation for a thousand standard cubic feet per day, a common measure for volume of gas. Standard conditions are normally set at 60oF and 14.7 psia.
1796thousand standard cubic feet per day
1797None
1798None
1799--
1800multiple rate tests
18011.n. [Well Testing]
1802Tests conducted at a series of different flow rates for the purpose of determining well deliverability, typically in gas wells where non-Darcy flow near the well results in a rate-dependent skin effect. Multiple-rate tests are sometimes required by regulatory bodies.
1803gas-well deliverability, non-Darcy flow, skin effect
1804None
1805None
1806--
1807mechanical diversion
18081.n. [Well Workover and Intervention]
1809The use of mechanical devices, such as ball sealers, packers and straddle-packer assemblies, to divert reservoir treatments to the target zone. Ball sealers and solid-particle diverting agents incorporated into the treatment fluid form a temporary plug in the perforations accepting the most fluid flow, thereby diverting the remaining treatment fluid to the less permeable zones. Packers and straddle-packer assemblies function by performing several short treatments over a longer interval to help ensure an even treatment over the entire zone.
1810None
1811None
1812None
1813--
1814mineral
18151.n. [Geology]
1816A crystalline substance that is naturally occurring, inorganic, and has a unique or limited range of chemical compositions. Minerals are homogeneous, having a definite atomic structure. Rocks are composed of minerals, except for rare exceptions like coal, which is a rock but not a mineral because of its organic origin. Minerals are distinguished from one another by careful observation or measurement of physical properties such as density, crystal form, cleavage (tendency to break along specific surfaces because of atomic structure), fracture (appearance of broken surfaces), hardness, luster and color. Magnetism, taste and smell are useful ways to identify only a few minerals.
1817anhydrite, barite, bentonite, coal, density, dolomite, dolomitization, evaporite, felsic, geochemistry, hydrate, hydrate, hydrothermal, hydrothermal alteration, mafic, mica, montmorillonite, quartz, rhombohedral packing, rock, sediment, silicate mineral, smectite, vug
1818None
1819None
1820--
1821msds
18221.n. [Drilling Fluids]
1823A specific document that shows important physical and chemical characteristics of a chemical or product to alert a user, transporter or other interested party to potential safety hazards that may be associated with the material. The MSDS also contains treatments for exposure or ingestion as well as the type of equipment needed for safe handling. An MSDS is a legal requirement in most countries for all aspects of commerce involving chemicals.
1824None
1825None
1826Material Safety Data Sheet
1827--
1828multishot survey
18291.n. [Reservoir Characterization]
1830A technique for determining the deviation of a wellbore. The multishot tool provides more accuracy than the single-shot tool and is usually used in highly deviated wells.
1831single-shot survey
1832None
1833None
1834--
1835medium induction
18361.n. [Formation Evaluation]
1837A particular type of induction log designed to read an intermediate distance into the formation while maintaining good vertical resolution. The medium-induction array of eight coils (IM) is produced by three transmitters and five receivers running at 20 kHz. A small fourth transmitter coil was added in tools built since 1968. The midpoint of the integrated radial geometrical factor is 30 in. [76 cm] in radius. The vertical resolution is about 4 ft [1.2 m] but varies with conditions. The IM is combined with a deep-induction log on the same sonde to produce a dual induction log.
1838resistivity log
1839None
1840IM
1841--
1842mineral interest
18431.n. [Oil and Gas Business]
1844Ownership of the right to exploit, mine or produce all minerals lying beneath the surface of a property. In this case, minerals include all hydrocarbons. Mineral interests include: 1. the right to use as much of the surface as is reasonably necessary to access the minerals,2. the right to execute any conveyances of mineral rights,3. the right to receive bonus consideration,4. the right to receive delay rentals and5. the right to receive royalty. Any or all of the above five rights of mineral ownership may be conveyed by the mineral owner.
1845bonus consideration, delay rental, royalty
1846None
1847None
1848--
1849mt
18501.n. [Geophysics]
1851An electromagnetic method used to map the spatial variation of the Earth's resistivity by measuring naturally occurring electric and magnetic fields at the Earth's surface. These natural EM fields are generated (at all frequencies) in the Earth's atmosphere mainly by lightning strokes and by interactions between the solar wind and the ionosphere. In the most general MT method, the horizontal components of the electric field and all three components of the magnetic field are measured at the surface. The measurements are used to determine specific ratios of electric to magnetic field components called tensor impedances. The technique was introduced the French geophysicist Louis Cagniard in the 1950s and has been popular for mineral exploration and regional geophysical mapping. It is used in oil exploration for low-cost reconnaissance of sedimentary basins and for exploration in areas where seismic surveys are difficult because of severe topography or the presence high-impedance volcanic rocks near the surface. The resolution of MT surveys is limited by the diffusive nature of EM propagation in the earth; it is usually on the order of hundreds of meters to kilometers. But the MT method can probe the Earth to depths of several tens of kilometers.
1852None
1853None
1854magnetotelluric method
1855--
1856mutual solvent
18571.n. [Well Workover and Intervention]
1858A chemical additive for stimulation treatments that is soluble in oil, water and acid-based treatment fluids. Mutual solvents are routinely used in a range of applications, such as removing heavy hydrocarbon deposits, controlling the wettability of contact surfaces before, during or after a treatment, and preventing or breaking emulsions. A commonly used mutual solvent is ethyleneglycolmonobutyl ether, generally known as EGMBE.
1859None
1860None
1861None
1862--
1863membrane potential
18641.n. [Formation Evaluation]
1865The electromagnetic force generated across an ion-selective membrane when solutions on either side of the membrane have different salinities. Shales and clays are cationic membranes, since they allow the passage of cations, such as Na+, but not anions, such as Cl-. When the drilling mud in the borehole and the formation water have different salinities, a membrane potential is generated at the boundary between a shale and a permeable formation. This potential is one component of the electrochemical potential, from which the spontaneous potential (SP) log is derived. The other, much smaller component is the liquid-junction potential. The membrane potential is reduced if the shale is not a good cationic membrane, or in other words has a low cation-exchange capacity.A membrane potential may also be generated across the mudcake if there is no flushed zone; for example if the mud filtrate has moved vertically since invasion took place, and by clay within a shaly sand, but with the opposite polarity to the normal SP potentials.The membrane potential is also used in core analysis to determine the cation-exchange capacity of a sample. In this case, the clay within the sample is the ion-selective membrane, and the potential generated across it is related to the cation-exchange capacity per unit pore volume, Qv. As a method of measuring Qv, the technique is faster than the multiple salinity method, and more representative of the in-situ value than destructive methods such as conductometric titration. However, care is needed in making the measurement and deriving the appropriate Qv.
1866electrokinetic potential, K coefficient, static spontaneous potential
1867None
1868None
1869--
1870minifrac
18711.n. [Well Workover and Intervention]
1872A small fracturing treatment performed before the main hydraulic fracturing treatment to acquire critical job design and execution data and confirm the predicted response of the treatment interval. The minifrac procedure provides key design data from the parameters associated with the injection of fluids and the subsequent pressure decline. The final job procedures and treatment parameters are refined according to the results of the minifrac treatment.
1873None
1874None
1875None
1876--
1877mud
18781.n. [Drilling Fluids]
1879A term that is generally synonymous with drilling fluid and that encompasses most fluids used in hydrocarbon drilling operations, especially fluids that contain significant amounts of suspended solids, emulsified water or oil. Mud includes all types of water-base, oil-base and synthetic-base drilling fluids. Drill-in, completion and workover fluids are sometimes called muds, although a fluid that is essentially free of solids is not strictly considered mud.
1880conventional mud, emulsion mud, invert-emulsion oil mud, lubricant, mud weight, mudding up, native-solids mud, oil mud, pill, reserve-mud pit, returns, slug, slurry, spud mud, suspended solids, unweighted mud, weighted mud
1881drilling mud
1882None
1883--
1884mwd
18851.n. [Drilling]
1886The evaluation of physical properties, usually including pressure, temperature and wellbore trajectory in three-dimensional space, while extending a wellbore. MWD is now standard practice in offshore directional wells, where the tool cost is offset by rig time and wellbore stability considerations if other tools are used. The measurements are made downhole, stored in solid-state memory for some time and later transmitted to the surface. Data transmission methods vary from company to company, but usually involve digitally encoding data and transmitting to the surface as pressure pulses in the mud system. These pressures may be positive, negative or continuous sine waves. Some MWD tools have the ability to store the measurements for later retrieval with wireline or when the tool is tripped out of the hole if the data transmission link fails. MWD tools that measure formation parameters (resistivity, porosity, sonic velocity, gamma ray) are referred to as logging-while-drilling (LWD) tools. LWD tools use similar data storage and transmission systems, with some having more solid-state memory to provide higher resolution logs after the tool is tripped out than is possible with the relatively low bandwidth, mud-pulse data transmission system.
1887None
1888mud pulse telemetry
1889measurements-while-drilling
1890--
1891memory gauge
18921.n. [Well Workover and Intervention]
1893A type of electronic pressure gauge that samples and records downhole pressures, with the data being stored, ready for downloading to acquisition equipment when the tool assembly has been retrieved to surface. Memory gauges are generally used to measure bottomhole pressures and temperatures in response to various production rates in tests to assess well productivity and reservoir performance.
1894pressure gauge
1895None
1896None
1897--
1898minimum restriction
18991.n. [Well Completions]
1900The smallest diameter present in a wellbore through which a tool string must pass to enable access to the operating depth or zone of interest. The minimum restriction determines the maximum tool string outside diameter and may influence the configuration of the assembled tools or equipment. The minimum restriction should be considered in both running and retrieving modes if any increase in tool string outside diameter is likely, such as when perforating or when using inflatable packers.
1901None
1902None
1903None
1904--
1905mud acid
19061.n. [Well Completions, Well Workover and Intervention]
1907A mixture of hydrofluoric acid [HF] and hydrochloric acid [HCl] or organic acid used as the main fluid in a sandstone matrix treatment. Hydrochloric acid or organic acid is mixed with HF to keep the pH low when it spends, thereby preventing detrimental precipitates. The name mud acid was given to these mixtures because they were originally developed to treat damage from siliceous drilling muds. Mud acid is also called hydrofluoric-hydrochloric acid.
1908fluoboric acid, hydrofluoric acid, organic acid
1909None
1910None
1911--
1912mysid shrimp
19131.n. [Drilling Fluids]
1914The common name for the small shrimp species Mysidopsis bahia, which is used as the test organism in a US EPA bioassay test protocol.
1915emulsion mud, EPA, LC50, Minerals Management Service, NPDES, potassium mud, sheen test
1916None
1917None
1918--
1919n
19201.n. [Formation Evaluation]
1921The exponent, n, in the relation of water saturation, Sw, to resistivity index, I (I = Sw-n) for a sample of rock. It expresses the effect on theresistivity of desaturating the sample, or replacing water with a non-conductive fluid. In petrophysically simple,water-wet rocks (Archie rocks), n is constant for different values of Sw, and a single average n can be found for a particularreservoir or formation. A typical value is 2. In more complex rocks, n changes with Sw, although often being about 2 near Sw = 1. In rocks with conductive minerals, such asshaly sands, n becomes increasingly lower as Sw is reduced. This change is negligible for high-salinity waters, but increases as the salinity is reduced. In shaly-sand saturation equations, such as Waxman-Smits, dual water, SGS and CRMM, n is the intrinsic n, determined with high-salinity water or with theclay effects removed. The variation of I with Sw is then predicted, with varying success, by the different equations. In carbonates with multiplepore types, such as fractures, vugs, interparticleporosity and microporosity, n may change as each pore type is desaturated. A different n may be used for a different range of Sw. In all cases, n increases if any pores are oil-wet. Values up to 8 have been reported in very oil-wet rocks.
1922None
1923None
1924None
1925--
1926natural gas
19271.n. [Geology]
1928A naturally occurring mixture of hydrocarbon gases that is highly compressible and expansible. Methane [CH4] is the chief constituent of most natural gas (constituting as much as 85% of some natural gases), with lesser amounts of ethane [C2H6], propane [C3H8], butane [C4H10] and pentane [C5H12]. Impurities can also be present in large proportions, including carbon dioxide, helium, nitrogen and hydrogen sulfide.
1929carbon dioxide, coal, condensate, dry gas, hydrate, hydrocarbon, hydrogen sulfide, maturity, methane, petroleum, retrograde condensation, source rock, sweet, wet gas
1930None
1931None
1932--
1933natural gas
19342.n. [Shale Gas]
1935Natural gas produced from shale reservoirs is known as shale gas. The composition of the gas stream is a function of the thermal maturity of the rock. Thermally immature rocks will contain heavier hydrocarbon components, possibly even liquid components. Overmature reservoirs typically contain appreciable quantities of carbon dioxide [CO2].
1936None
1937None
1938None
1939--
1940neutron porosity
19411.adj. [Formation Evaluation]
1942Referring to a log of porosity based on the effect of the formation on fast neutrons emitted by a source. Hydrogen has by far the biggest effect in slowing down and capturing neutrons. Since hydrogen is found mainly in the pore fluids, the neutron porosity log responds principally to porosity. However, the matrix and the type of fluid also have an effect. The log is calibrated to read the correct porosity assuming that the pores are filled with fresh water and for a given matrix (limestone, sandstone or dolomite). It is presented in units of porosity (vol/vol or p.u.) for the matrix chosen. Older logs were presented in counts per second or API units. The depth of investigation is several inches, so that the log reads mainly in the flushed zone.The neutron porosity log is strongly affected by clay and gas. Hydrogen occurs in clays and hydrated minerals as well as pore fluids. Gas has a low hydrogen density, so that gas zones have a very low apparent porosity. The measurement is based on either thermal or epithermal neutron detection. Thermal neutrons have about the same energy as the surrounding matter, typically less than 0.4 eV, while epithermal neutrons have higher energy, between about 0.4 and 10 eV. Being a statistical measurement, the precision is greatest at high count rates, which in this case occurs at low porosity.Neutron porosity logs were introduced in the early 1940s. The first tools were known as neutron-gamma tools, since the detector measured the gamma rays emitted on capture. Neutron-neutron tools, using a thermal neutron detector were introduced in about 1950.
1943alpha processing, compensated neutron log, epithermal neutron porosity measurement, excavation effect, flushed zone, hydrogen index, limestone porosity unit, limestone-compatible scale, thermal neutron porosity measurement
1944None
1945None
1946--
1947nonconductive drilling fluid
19481.n. [Drilling Fluids]
1949A mud that does not conduct electricity sufficiently well to allow spontaneous potential (SP) logging or resistivity logging. Oil- and synthetic-base muds are nonconductive drilling fluids. Water muds are not in this category.
1950oil-base mud, resistivity log, spontaneous potential, synthetic-base mud, water-base drilling fluid
1951None
1952None
1953--
1954nace
19551.n. [General Terms]
1956NACE, or NACE International, is a worldwide professional organization committed to corrosion prevention and control. NACE, founded in 1943, is headquartered in Houston, Texas, USA. Areas of focus include oil and gas, water, transportation and infrastructure protection. The original name was National Association of Corrosion Engineers—the source of its NACE acronym—although the organization formally adopted NACE International—The Corrosion Society, in 1993. Among its activities, the organization offers technical training and certification programs, conducts regional and international conferences, publishes industry standards, reports, publications and technical journals and assists in government relations activities. The NACE Materials Requirements include the widely used MR0175, corrosion resistant materials for oil and gas applications, and MR0103, sulfide stress cracking in corrosive environments.Publications can be ordered from NACE at http://www.nace.org/.References:Petroleum and Natural Gas Industries—Materials for Use in H2S-Containing Environments in Oil and Gas Production, Houston: NACE International, ANSI/NACE MR0175/ISO 15156, 3rd ed., 2015.Petroleum and Natural Gas Industries—Metallic Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments, Houston: NACE International, MR0103/ISO 17945, 2015.
1957None
1958None
1959None
1960--
1961naturally flowing well
19621.n. [Well Testing]
1963A well in which the formation pressure is sufficient to produce oil at a commercial rate without requiring a pump. Most reservoirs are initially at pressures high enough to allow a well to flow naturally.
1964formation pressure
1965None
1966Antonyms:pumping well
1967--
1968neutron activation log
19691.n. [Production Logging]
1970A record of elemental concentrations derived from the characteristic energy levels of gamma rays emitted by a nucleus that has been activated by neutron bombardment. In the context of production logging, the term normally refers to the activation of silicon and aluminum to determine the quality of a gravel pack. Silicon and aluminum are activated by a neutron source to produce isotopes that decay with a half-life of 2.3 minutes emitting a 1.78 MeV gamma ray. These gamma rays are counted in a detector placed below the source, with a high count indicating a high quantity of silicon in a sand pack, or aluminum in a bauxite pack. The log is run slowly so that oxygen and other activated elements have decayed before the detector crosses the activated interval.The carbon-oxygen log, elemental-capture spectroscopy log, pulsed-neutron spectroscopy log, aluminum-activation log and the oxygen-activation log are also examples of neutron-activation logs.
1971activation log, aluminum activation log, elemental capture spectroscopy, gravel-pack log, induced gamma ray spectroscopy, oxygen activation, production log, pulsed neutron spectroscopy log
1972None
1973None
1974--
1975non darcy flow
19761.n. [Well Testing]
1977Fluid flow that deviates from Darcy's law, which assumes laminar flow in the formation. Non-Darcy flow is typically observed in high-rate gas wells when the flow converging to the wellbore reaches flow velocities exceeding the Reynolds number for laminar or Darcy flow, and results in turbulent flow. Since most of the turbulent flow takes place near the wellbore in producing formations, the effect of non-Darcy flow is a rate-dependent skin effect.
1978laminar flow, skin effect, turbulent flow
1979None
1980None
1981--
1982naphthene base crude oil
19831.n. [Production Testing]
1984Crude oil containing asphaltic materials but very little or no paraffin wax. This type of oil is suitable for making gasoline, lubricating oil and asphalt. It is also called asphalt-base crude.
1985paraffin-base crude oil
1986None
1987None
1988--
1989naturally occurring radioactive materials norm
19901.n. [Well Completions]
1991Materials typically found in certain types of barium or strontium scales that may be deposited in the wellbore or production tubulars. Any attempt to remove and dispose of NORM materials should be performed according to the legislation and policies associated with such potentially hazardous materials.
1992production tubing
1993None
1994None
1995--
1996newtonian fluid
19971.n. [Drilling Fluids]
1998A typical fluid. A fluid is said to be Newtonian if its viscosity—a measure of a fluid’s ability to resist flow—only varies in response to changes in temperature or pressure.A Newtonian fluid will take the shape of its container.Under constant temperature and pressure conditions, the viscosity of a Newtonian fluid is the constant of proportionality, or the ratio, between the shear stress that builds in the fluid to resist flow and the shear rate applied to the fluid to induce flow; the viscosity is the same for all shear rates applied to the fluid.Water, sugar solutions, glycerin, silicone oils, light-hydrocarbon oils, air and other gases are Newtonian fluids. Most drilling fluids are non-Newtonian fluids.
1999capillary tube viscometer, direct-indicating viscometer, Herschel-Bulkley fluid, non-Newtonian fluid, power-law fluid, rheology, shear rate, shear stress, viscosity
2000None
2001None
2002--
2003non newtonian fluid
20041.n. [Drilling Fluids]
2005Not a typical fluid. Unlike a Newtonian fluid, which displays liquid behavior, a non-Newtonian fluid has properties of a liquid and of a solid. Under certain conditions, a non-Newtonian fluid flows as a liquid and under other conditions, it exhibits elasticity, plasticity and strength similar to a solid. In addition, unlike Newtonian fluids, the viscosity of many non-Newtonian fluids varies with shear rate.Four classes of non-Newtonian fluids depend on how the fluid viscosity—a measure of a fluid’s ability to resist flow—varies in response to the duration and magnitude of applied shear rate. The viscosity of:Thixotropic fluids decreases over time under shearing. For example, solid honey becomes a liquid after continuous stirring.Rheopectic fluids increases over time under shearing. For example, cream will thicken after continuous stirring.Pseudoplastic fluids decreases with increasing shear rate; these fluids exhibit shear thinning behavior. For example, ketchup will squirt through a hole in a bottle top at high velocity but stand still as a dollop on a plate.Dilatant fluids increases with increasing shear rate; these fluids exhibit shear thickening behavior.Most successful drilling fluids are non-Newtonian and exhibit behaviors that are described by rheological mathematical models of shear stress, or resistance, as a function of shear rate. In the Bingham plastic model, flow will not begin until the shear stress attains a minimum value, the yield stress, after which the flow is similar to that of a Newtonian fluid because the viscosity is constant and does not vary with shear rate.Pseudoplasticity, or shear thinning, is a non-Newtonian behavior that is desirable for drilling fluids. Power-law and Herschel-Bulkley models describe pseudoplastic behavior, in which the slope—the viscosity—of the shear stress versus shear rate curve decreases as the shear rate decreases.
2006Bingham plastic model, Brookfield viscometer, direct-indicating viscometer, guar gum, Herschel-Bulkley fluid, Newtonian fluid, plastic fluid, power-law fluid, pseudoplastic, rheology, shear rate, shear stress, viscosity, XC polymer
2007None
2008None
2009--
2010naphthene base crude oil
20111.n. [Production Testing]
2012Crude oil containing asphaltic materials but very little or no paraffin wax. This type of oil is suitable for making gasoline, lubricating oil and asphalt. It is also called asphalt-base crude.
2013paraffin-base crude oil
2014None
2015None
2016--
2017needle valve
20181.n. [Production]
2019A type of small valve used for flow metering, having a tapered needlepoint plug or closure element and a seat having a small orifice.
2020None
2021None
2022None
2023--
2024nipple
20251.n. [Drilling, Production]
2026Any short piece of pipe, especially if threaded at both ends with male threads.
2027None
2028None
2029None
2030--
2031nipple
20322.n. [Well Completions]
2033A completion component fabricated as a short section of heavy wall tubular with a machined internal surface that provides a seal area and a locking profile. Landing nipples are included in most completions at predetermined intervals to enable the installation of flow-control devices, such as plugs and chokes. Three basic types of landing nipple are commonly used: no-go nipples, selective-landing nipples and ported or safety-valve nipples.
2034no-go landing nipple, selective nipple
2035None
2036None
2037--
2038normal fault
20391.n. [Geology]
2040A type of fault in which the hanging wall moves down relative to the footwall, and the fault surface dips steeply, commonly from 50o to 90o. Groups of normal faults can produce horst and graben topography, or a series of relatively high- and low-standing fault blocks, as seen in areas where the crust is rifting or being pulled apart by plate tectonic activity. A growth fault is a type of normal fault that forms during sedimentation and typically has thicker strata on the downthrown hanging wall than the footwall.
2041antithetic fault, crust, fault, growth fault, inversion, plate tectonics, rift, sedimentation, stratum, synthetic fault
2042None
2043None
2044--
2045naphthenic hydrocarbon
20461.n. [Drilling Fluids]
2047A type of organic compound of carbon and hydrogen that contains one or more saturated cyclic (ring) structures, or contains such structures as a major portion of the molecule. The general formula is CnH2n. Naphthenic compounds are sometimes called naphthenes, cycloparaffins or hydrogenated benzenes. Naphtha is a refined petroleum fraction that contains a high percentage of these types of hydrocarbons. In drilling fluids, particularly oil-base muds, the amounts and types of hydrocarbons in the mud can be an important parameter in the overall performance of the mud.
2048aliphatic compound, aromatic hydrocarbon, olefinic hydrocarbon, paraffinic hydrocarbon
2049None
2050None
2051--
2052neritic
20531.adj. [Geology]
2054Describing the environment and conditions of the marine zone between low tide and the edge of the continental shelf, a depth of roughly 200 m [656 ft]. A neritic environment supports marine organisms, also described as neritic, that are capable of surviving in shallow water with moderate exposure to sunlight.
2055abyssal, bathyal, benthic, depositional environment, littoral, marine, shelf
2056None
2057None
2058--
2059nipple up
20601.vb. [Drilling]
2061To put together, connect parts and plumbing, or otherwise make ready for use. This term is usually reserved for the installation of a blowout preventer stack.
2062BOP stack
2063None
2064None
2065--
2066nipple up
20672.n. [Well Completions]
2068The process of assembling well-control or pressure-control equipment on the wellhead.
2069None
2070None
2071Antonyms:nipple down, nipple-down
2072--
2073normal incidence
20741.n. [Geophysics]
2075The case in which a wavefront is parallel to an interface and its raypath is perpendicular, or normal, to the interface as the wave impinges upon the interface.
2076angle of incidence, raypath, reflection coefficient, Snell's law, two-way traveltime, wave
2077None
2078None
2079--
2080native clay
20811.n. [Drilling Fluids]
2082Clays incorporated into a so-called native-solids mud when drilling shallow formations. Native clays are undesirable in muds that are (or will be) weighted with barite. The viscosity of weighted fluids can rise quickly with added native clays, making it difficult to control and pump the mud. Better mud properties result when the drilled solids level, including the level of native clays, is kept low.
2083bentonite, clay-water interaction, gumbo, native-solids mud, shale, spud mud, unweighted mud, weighted mud
2084None
2085None
2086--
2087net revenue interest
20881.n. [Oil and Gas Business]
2089A share of production after all burdens, such as royalty and overriding royalty, have been deducted from the working interest. It is the percentage of production that each party actually receives.
2090overriding royalty, royalty, working interest
2091None
2092None
2093--
2094nitrogen cushion
20951.n. [Perforating, Well Completions]
2096A column of high-pressure nitrogen typically applied to a tubing string in preparation for drillstem testing or perforating operations in which the reservoir formation is to be opened to the tubing string. The nitrogen cushion allows a precise pressure differential to be applied before opening flow from the reservoir. Once flow begins, the nitrogen cushion pressure can be easily and safely bled down to flow formation fluids under a high degree of control.
2097drillstem test, formation fluid
2098None
2099None
2100--
2101normal mode
21021.n. [Formation Evaluation]
2103A type of acoustic energy that propagates in one direction while being confined in the other two directions, in this case by the borehole wall. Normal modes are propagated as reflections off the borehole wall, and exist only in hard rock. They are highly dispersive, starting with the formation shear velocity at a certain cutoff frequency and decreasing at high frequencies to the borehole fluid velocity. Below the cutoff frequency, they do not exist. Normal mode #0 is often considered to be the tube wave and starts at zero frequency. Normal mode #1 is called the pseudoRayleigh, and starts at around 5 kHz. The other normal modes start at increasingly higher frequencies.
2104acoustic mode, flexural mode, hard rock, leaky mode, normal, Stoneley wave
2105None
2106None
2107--
2108native solids mud
21091.n. [Drilling Fluids]
2110A mud in which the suspended solids are dispersed clays, sand, chert and other rock that originated from formations being drilled. A spud mud is commonly a type of native-solids mud. Native muds can be economically diluted with water and passed through banks of desilters and desanders to keep solids down. No expensive weighting materials are being discarded and replaced in such a process. At the depth that higher density is required, native mud is usually totally or partially discarded and new mud is made using commercially prepared mud additives and barite.
2111acrylate polymer, colloidal solids, make-up water, mud, mud additive, mudding up, native clay, spud mud
2112None
2113unweighted mud
2114--
2115neural networks
21161.n. [Reservoir Characterization]
2117A concept for advanced computer calculations developed by Alan Turing to mimic some of the operations of the neurons in a brain. Memory elements (neurons) are conceptually interconnected by multiple paths connected with on-off switches to emulate the synapses of the brain. The original intent was to build a data-processing machine.Modern applications reduce the concept to structured digital software processing models. Repeated processing through a neural network allows the network to learn from the data it processes. The learned process obtained from a set of training data with solutions can then be applied to other data sets for which no solution exists. An oilfield example includes training a network with wireline log and core data and then using the network to interpret further log data in terms of the core data. Neural networks are also being used in seismic processing, geological mapping and petrophysical analysis.
2118artificial intelligence, log, petrophysical model, wireline log
2119None
2120None
2121--
2122nitrogen kickoff
21231.n. [Well Completions]
2124Another term for nitrogen lift, the use of nitrogen gas circulated into the production conduit to displace liquids and reduce the hydrostatic pressure created by the fluid column. Nitrogen lifting is a common technique used to initiate production on a well following workover or overbalanced completion. A coiled tubing string is generally used to apply the treatment, which involves running to depth while pumping high-pressure nitrogen gas. Once the kill-fluid column is unloaded and the well is capable of natural flow, the coiled tubing string is removed and the well is prepared for production.
2125coiled tubing string, hydrostatic pressure
2126None
2127None
2128--
2129normal moveout
21301.n. [Geophysics]
2131The effect of the separation between receiver and source on the arrival time of a reflection that does not dip, abbreviated NMO. A reflection typically arrives first at the receiver nearest the source. The offset between the source and other receivers induces a delay in the arrival time of a reflection from a horizontal surface at depth. A plot of arrival times versus offset has a hyperbolic shape.
2132apparent anisotropy, arrival time, brute stack, dynamic correction, moveout, normal-moveout correction, offset, receiver, reflection, source, spacing, stacking velocity, velocity analysis
2133None
2134NMO
2135--
2136normal moveout
21372.n. [Geophysics]
2138The procedure in seismic processing that compensates for the effects of the separation between seismic sources and receivers in the case of a horizontal reflector.
2139processing, receiver, reflector, source
2140None
2141NMO
2142--
2143native state core
21441.n. [Formation Evaluation]
2145A core taken so as to preserve the in-situ water saturation of the rock. A native-state core is usually drilled with oil-base mud or crude oil from the same reservoir.
2146fresh core, restored state core, water saturation
2147None
2148None
2149--
2150neutralizing solution
21511.n. [Well Workover and Intervention]
2152A fluid prepared to counteract the corrosive effect of acids or acidic treatment fluids. Neutralizing solutions generally are used when the components to be protected cannot be adequately flushed or when there is a risk that residual fluids may cause problems through prolonged exposure. Neutralizing solutions are commonly formulated with soda ash to provide an inexpensive, nondamaging alkaline fluid that does not create excessive disposal difficulties.
2153None
2154None
2155None
2156--
2157nitrogen lift
21581.n. [Well Completions]
2159The use of nitrogen gas circulated into the production conduit to displace liquids and reduce the hydrostatic pressure created by the fluid column. Nitrogen lifting is a common technique used to initiate production on a well following workover or overbalanced completion. A coiled tubing string is generally used to apply the treatment, which involves running to depth while pumping high-pressure nitrogen gas. Once the kill-fluid column is unloaded and the well is capable of natural flow, the coiled tubing string is removed and the well is prepared for production.
2160coiled tubing string, hydrostatic pressure
2161None
2162nitrogen kickoff
2163--
2164npdes
21651.n. [Drilling Fluids]
2166Abbreviation for "National Pollutant Discharge Elimination System." The US Congress passed this Clean Water Act to control discharges of contaminants. Discharges are allowed in to US water only by NPDES permits. Drilling fluids, drill cuttings, produced water, drilling rig deck drainage and blowout preventor fluids are covered specifically. Barite must be monitored for heavy metals to allow mud discharges. Oils are banned from discharge.
2167bioassay, CERCLA, CWA, emulsion mud, EPA, heavy metal, HSE, Minerals Management Service, mysid shrimp, OOC, sheen test, synthetic-base fluid, synthetic-base mud
2168None
2169None
2170--
2171native solids mud
21721.n. [Drilling Fluids]
2173A mud in which the suspended solids are dispersed clays, sand, chert and other rock that originated from formations being drilled. A spud mud is commonly a type of native-solids mud. Native muds can be economically diluted with water and passed through banks of desilters and desanders to keep solids down. No expensive weighting materials are being discarded and replaced in such a process. At the depth that higher density is required, native mud is usually totally or partially discarded and new mud is made using commercially prepared mud additives and barite.
2174acrylate polymer, colloidal solids, make-up water, mud, mud additive, mudding up, native clay, spud mud
2175None
2176unweighted mud
2177--
2178neutron activation log
21791.n. [Production Logging]
2180A record of elemental concentrations derived from the characteristic energy levels of gamma rays emitted by a nucleus that has been activated by neutron bombardment. In the context of production logging, the term normally refers to the activation of silicon and aluminum to determine the quality of a gravel pack. Silicon and aluminum are activated by a neutron source to produce isotopes that decay with a half-life of 2.3 minutes emitting a 1.78 MeV gamma ray. These gamma rays are counted in a detector placed below the source, with a high count indicating a high quantity of silicon in a sand pack, or aluminum in a bauxite pack. The log is run slowly so that oxygen and other activated elements have decayed before the detector crosses the activated interval.The carbon-oxygen log, elemental-capture spectroscopy log, pulsed-neutron spectroscopy log, aluminum-activation log and the oxygen-activation log are also examples of neutron-activation logs.
2181activation log, aluminum activation log, elemental capture spectroscopy, gravel-pack log, induced gamma ray spectroscopy, oxygen activation, production log, pulsed neutron spectroscopy log
2182None
2183None
2184--
2185nmo
21861.n. [Geophysics]
2187The effect of the separation between receiver and source on the arrival time of a reflection that does not dip, abbreviated NMO. A reflection typically arrives first at the receiver nearest the source. The offset between the source and other receivers induces a delay in the arrival time of a reflection from a horizontal surface at depth. A plot of arrival times versus offset has a hyperbolic shape.
2188None
2189None
2190normal moveout
2191--
2192nmo
21932.n. [Geophysics]
2194The procedure in seismic processing that compensates for the effects of the separation between seismic sources and receivers in the case of a horizontal reflector.
2195None
2196None
2197normal moveout
2198--
2199nuclear fluid densimeter
22001.n. [Production Logging]
2201A device for measuring the density of fluids in a completed well, using a radioactive source of gamma rays and a detector. In most instruments, a 137Cs (cesium) or 241Am (americium) source is used to induce Compton scattering, as in the openhole density measurement, except that the device is unfocused. The count rate at the detector then depends primarily on the density of the fluids in the well. In some devices, the fluids pass through an open space in the body of the tool within which the measurement is made. The results then reflect the density of the fluids passing through the tool. In other devices, the source and detector are isolated so that the gamma rays pass outside the tool. The results then reflect some average density of all the fluids within the well. In smaller casings, some formation signal may contaminate the measurement.Compared with a gradiomanometer, the nuclear fluid densimeter is a less direct measurement of density, and has a statistical uncertainty and less resolution. On the other hand, it is not affected by well deviation, friction or kinetic effects.
2202fluid-density log, holdup log, photon log, production log
2203None
2204None
2205--
2206natural fracture
22071.n. [Shale Gas, Geology]
2208A crack or surface of breakage within rock not related to foliation or cleavage in metamorphic rock along which there has been no movement. A fracture along which there has been displacement is a fault. When walls of a fracture have moved only normal to each other, the fracture is called a joint. Fractures can enhance permeability of rocks greatly by connecting pores together, and for that reason, fractures are induced mechanically in some reservoirs in order to boost hydrocarbon flow.Fractures may also be referred to as natural fractures to distinguish them from fractures induced as part of a reservoir stimulation or drilling operation. In some shale reservoirs, natural fractures improve production by enhancing effective permeability. In other cases, natural fractures can complicate reservoir stimulation.
2209competent, dilatancy, en echelon, fracture gradient, halite, incompetent, permeability, pore, S-wave, strain, structure
2210None
2211None
2212--
2213neutron capture
22141.n. [Formation Evaluation]
2215A neutron interaction in which the neutron is absorbed by the target nucleus, producing an isotope in an excited state. The activated isotope de-excites instantly through the emission of characteristic gamma rays. Neutron capture, also called thermal capture, usually occurs at low thermal energies at which the neutrons have about the same energy as the surrounding matter, typically below 0.4 eV (0.025 eV at room temperature). Some elements are better thermal absorbers than others. Neutron capture is an important principle behind the pulsed neutron capture log, the elemental capture spectroscopy log, the pulsed neutron spectroscopy log and the thermal neutron porosity measurement.
2216chemical neutron source, fast-neutron reaction, inelastic neutron scattering, neutron generator, neutron interactions
2217thermal capture
2218None
2219--
2220nmr
22211.n. [Geophysics]
2222Pertaining to a measurement of the nuclear magnetic properties of formation hydrogen. The basic core and log measurement is the T2 decay, presented as a distribution of T2 amplitudes versus time at each sample depth, typically from 0.3 ms to 3 s. The T2 decay is further processed to give the total pore volume (the total porosity) and pore volumes within different ranges of T2. The most common volumes are the bound fluid and free fluid. A permeability estimate is made using a transform such as the Timur-Coates or SDR permeability transforms. By running the log with different acquisition parameters, direct hydrocarbon typing and enhanced diffusion are possible.
2223magnetic resonance
2224None
2225nuclear magnetic resonance
2226--
2227nmr
22282.adj. [Formation Evaluation]
2229Pertaining to a measurement of the nuclear magnetic properties of formation hydrogen. The basic core and log measurement is the T2 decay, presented as a distribution of T2 amplitudes versus time at each sample depth, typically from 0.3 ms to 3 s. The T2 decay is further processed to give the total pore volume (the total porosity) and pore volumes within different ranges of T2. The most common volumes are the bound fluid and free fluid. A permeability estimate is made using a transform such as the Timur-Coates or SDR permeability transforms. By running the log with different acquisition parameters, direct hydrocarbon typing and enhanced diffusion are possible.
2230None
2231None
2232nuclear magnetic resonance
2233--
2234nuclear magnetic resonance
22351.n. [Reservoir Characterization, Formation Evaluation]
2236A phenomenon by which a nucleus absorbs electromagnetic radiation of a specific frequency in the presence of a strong magnetic field. Isidor Isaac Rabi (1898 to 1988), an American physicist born in Austria, first detected magnetic resonance in 1938. Since then, magnetic resonance has been applied to the detection of light atoms (such as hydrogen in hydrocarbons) and as a nondestructive way to study the human body.
2237None
2238None
2239NMR
2240--
2241nuclear magnetic resonance
22422.adj. [Formation Evaluation]
2243Pertaining to a measurement of the nuclear magnetic properties of formation hydrogen. The basic core and log measurement is the T2 decay, presented as a distribution of T2 amplitudes versus time at each sample depth, typically from 0.3 ms to 3 s. The T2 decay is further processed to give the total pore volume (the total porosity) and pore volumes within different ranges of T2. The most common volumes are the bound fluid and free fluid. A permeability estimate is made using a transform such as the Timur-Coates or SDR permeability transforms. By running the log with different acquisition parameters, direct hydrocarbon typing and enhanced diffusion are possible.
2244nuclear magnetic resonance measurement
2245None
2246NMR
2247--
2248natural gamma ray spectroscopy
22491.n. [Formation Evaluation]
2250The technique of measuring the spectrum, or number and energy, of gamma rays emitted as natural radioactivity by the formation. There are three sources of natural radioactivity in the Earth: 40K, 232Th and 238U, or potassium, thorium and uranium. These radioactive isotopes emit gamma rays that have characteristic energy levels. The quantity and energy of these gamma rays can be measured in a scintillation detector. A log of natural gamma ray spectroscopy is usually presented as a total gamma ray log and the weight fraction of potassium (%), thorium (ppm) and uranium (ppm). The primary standards for the weight fractions are formations with known quantities of the three isotopes. Natural gamma ray spectroscopy logs were introduced in the early 1970s, although they had been studied from the 1950s.
2251carbonate gamma ray, gamma ray log
2252None
2253None
2254--
2255neutron log
22561.n. [Formation Evaluation]
2257Normally synonymous with a neutron porosity log. However, the term is sometimes broadened to include an activation log.
2258activation log, chemical neutron source, neutron generator, neutron porosity
2259None
2260None
2261--
2262noise log
22631.n. [Production Logging]
2264A record of the sound measured at different positions in the borehole. Since fluid turbulence generates sound, high noise amplitudes indicate locations of greater turbulence such as leaks, channels and perforations. Noise logging is used primarily for channel detection, but has also been used to measure flow rates, identify open perforations, detect sand production and locate gas-liquid interfaces. The log may be either a continuous record against depth or a series of stationary readings. The log may indicate the total signal over all frequencies, the signal at a single frequency, or consist of a set of logs for different frequency ranges. Different frequency ranges can be tied to different sources of noise or different flow regimes.Although first introduced around 1955, the technique was not used commercially until after laboratory studies in the early 1970s.
2265audio measurement, production log
2266None
2267None
2268--
2269nuclear magnetic resonance measurement
22701.n. [Formation Evaluation]
2271A measurement of the nuclear magnetic resonance (NMR) properties of hydrogen in the formation. There are two phases to the measurement: polarization and acquisition. First, the hydrogen atoms are aligned in the direction of a static magnetic field (B0). This polarization takes a characteristic time T1. Second, the hydrogen atoms are tipped by a short burst from an oscillating magnetic field that is designed so that they precess in resonance in a plane perpendicular to B0. The frequency of oscillation is the Larmor frequency. The precession of the hydrogen atoms induces a signal in the antenna. The decay of this signal with time is caused by transverse relaxation and is measured by the CPMG pulse sequence. The decay is the sum of different decay times, called T2. The T2 distribution is the basic output of a NMR measurement.The NMR measurement made by both a laboratory instrument and a logging tool follow the same principles very closely. An important feature of the NMR measurement is the time needed to acquire it. In the laboratory, time presents no difficulty. In a log, there is a trade-off between the time needed for polarization and acquisition, logging speed and frequency of sampling. The longer the polarization and acquisition, the more complete the measurement. However, the longer times require either lower logging speed or less frequent samples.
2272dephasing, diffusion relaxation, echo spacing, logging tool, longitudinal relaxation, nuclear magnetic resonance, polarization time, relaxation time
2273None
2274None
2275--
2276obc
22771.n. [Geophysics]
2278Typically an assembly of vertically oriented geophones and hydrophones connected by electrical wires and deployed on the seafloor to record and relay data to a seismic recording vessel. Such systems were originally introduced to enable surveying in areas of obstructions (such as production platforms) or shallow water inaccessible to ships towing seismic streamers (floating cables). Recent developments provide four component (4C) seabed systems to record shear wave (S-wave) as well as P-wave energy.
2279acoustic positioning, cable, four-component seismic data, geophone, hydrophone, S-wave, streamer
2280None
2281None
2282--
2283oil pool
22841.n. [Geology]
2285A subsurface oil accumulation. An oil field can consist of one or more oil pools or distinct reservoirs within a single large trap. The term "pool" can create the erroneous impression that oil fields are immense caverns filled with oil, instead of rock filled with small oil-filled pores.
2286reservoir, trap
2287accumulation, field, oil field
2288None
2289--
2290ooc
22911.n. [Drilling Fluids]
2292The oil content of cuttings, normally expressed as grams of oil adsorbed per kilogram of dry cuttings. The value has been used as the basis for discharge regulations for oil-base muds in several operating areas.
2293None
2294None
2295oil on cuttings
2296--
2297ooc
22982.n. [Drilling Fluids]
2299Abbreviation for Offshore Operators Committee, a group of more than 85 oil and gas producers who operate in the Gulf or Mexico. OOC was formed in the 1950s. It interacts with various governmental organizations, such as the Environmental Protection Agency (EPA) and Minerals Management Service (MMS), to keep regulations up to date and economically sound. Many rules about discharge of mud and cuttings into Gulf waters have been developed jointly by OOC and the EPA.
2300CERCLA, EPA, MMS, NPDES, RCRA
2301None
2302None
2303--
2304osha
23051.n. [Drilling Fluids]
2306Abbreviation for Occupational Safety and Health Act of the US. OSHA laws protect safety and health of workers and give workers the right to know what materials they are handling. Safe handling of mud chemicals and the general safety of all drilling operations are of prime concern to OSHA, the operator and the mud engineer. Monitoring for toxic hydrogen sulfide [H2S] in air around the rig and testing mud for sulfides are an essential part of rig safety.
2307Garrett Gas Train, HSE, mud, sulfide
2308None
2309None
2310--
2311ocean bottom cable
23121.n. [Geophysics]
2313Typically an assembly of vertically oriented geophones and hydrophones connected by electrical wires and deployed on the seafloor to record and relay data to a seismic recording vessel. Such systems were originally introduced to enable surveying in areas of obstructions (such as production platforms) or shallow water inaccessible to ships towing seismic streamers (floating cables). Recent developments provide four component (4C) seabed systems to record shear wave (S-wave) as well as P-wave energy.
2314acoustic positioning, cable, four-component seismic data, geophone, hydrophone, S-wave, streamer
2315None
2316None
2317--
2318oil sand
23191.n. [Geology]
2320A porous sand layer or sand body filled with oil.
2321gas sand, sandstone
2322None
2323None
2324--
2325oil sand
23262.n. [Heavy Oil]
2327In the context of heavy oil, an oil sand is a porous rock layer, often considered to be a mixture of sand, clay, water, and bitumen. The term is predominantly used in Canada, where over 170 billion barrels of bitumen are estimated to be held by large oil sand deposits in the Athabasca, Cold Lake and Peace River regions of Alberta. Oils from such sands may have a gravity of less than 10° API. Both in-situ recovery and mining methods are used to extract the resource, with surface mining used for extracting deposits of extra heavy oil at shallow depths of less than 100 m [328 ft].
2328None
2329None
2330None
2331--
2332open flow potential
23331.n. [Well Completions]
2334The calculated maximum flow rate that a system may provide in the absence of restrictions. The term may be qualified as relating to a specific zone, such as a perforated interval or be used in referring to the production capability of the well.
2335None
2336None
2337None
2338--
2339open flow potential
23402.n. [Well Testing]
2341The theoretical flow capacity of gas wells if the bottomhole pressure could be reduced to atmospheric pressure. Test procedures to determine the AOF (Atmospheric Open-Flow) potential were often prescribed by law and enforced by state agencies. The open-flow potential capacity of the well was then used to determine the maximum rate that the gas well would be allowed to produce into a pipeline. During that period when there was an excessive amount of gas available for sale, this approach allowed an orderly method of allocating production rights to operators. The methodology is still used in some areas.The test required use of multiple rates, usually three or four, with measurement or calculation of the bottomhole pressure at the end of each flow period. The values of the difference between the square of the average reservoir pressure and the square of the bottomhole pressure were computed for each flow rate. These values were then plotted on the y-axis of a log-log plot versus the rate on the x-axis. The value of the open-flow potential is obtained by extrapolating the best straight line to the value of the average reservoir pressure squared minus atmospheric pressure squared, and then reading the corresponding rate off the x-axis.
2342gas-well deliverability, reservoir pressure
2343None
2344None
2345--
2346osmosis
23471.n. [Drilling Fluids]
2348The movement of water from one aqueous system to another through a semipermeable membrane. Osmotic movement is driven by activity differences between the two systems and can be considered as a vapor-phase transfer. An oil mud acts as an osmotic system. Emulsion film surrounding each brine droplet in an oil mud acts as semipermeable osmotic membrane and allows water molecules to pass back and forth, but restricts ions and larger molecules. Clays in shale formations also are aqueous systems that interact by osmosis with oil-mud droplets.
2349activity of aqueous solutions, balanced-activity oil mud, calcium chloride, Chenevert Method, hygrometer, oil-mud emulsifier, osmotic pressure
2350None
2351None
2352--
2353octahedral layer
23541.n. [Drilling Fluids]
2355One of the layers that constitute the atomic structure of the clay group of layeredsilicateminerals. The structure of these minerals can consist of two, three or four layers. The octahedral layer is a plane of aluminum hydroxide octahedra (aluminum at the center and hydroxides at all six corners). Another structural layer is a plane of silicon dioxide tetrahedra (silicon at the center and oxygen at all four corners of the tetrahedron). The tetrahedral and octahedral layers fit one on top of the other, with oxygen atoms being shared as oxide and hydroxide groups.
2356bentonite, silica layer, tetrahedral layer
2357None
2358None
2359--
2360oil water contact
23611.n. [Geology]
2362A bounding surface in a reservoir above which predominantly oil occurs and below which predominantly water occurs. Although oil and water are immiscible, the contact between oil and water is commonly a transition zone and there is usually irreducible water adsorbed by the grains in the rock and immovable oil that cannot be produced. The oil-water contact is not always a flat horizontal surface, but instead might be tilted or irregular.
2363downdip, fluid contact, gas-oil contact, gas-water contact, immiscible, miscible, reservoir, updip
2364None
2365OWC
2366--
2367open hole
23681.n. [Drilling]
2369The uncased portion of a well. All wells, at least when first drilled, have openhole sections that the well planner must contend with. Prior to running casing, the well planner must consider how the drilled rock will react to drilling fluids, pressures and mechanical actions over time. The strength of the formation must also be considered. A weak formation is likely to fracture, causing a loss of drilling mud to the formation and, in extreme cases, a loss of hydrostatic head and potential well control problems. An extremely high-pressure formation, even if not flowing, may have wellbore stability problems. Once problems become difficult to manage, casing must be set and cemented in place to isolate the formation from the rest of the wellbore. While most completions are cased, some are open, especially in horizontal or extended-reach wells where it may not be possible to cement casing efficiently.
2370barefoot, blowout, borehole, caliper log, casing point, cementing, completion, packer, tight hole, well control
2371None
2372None
2373--
2374ospar
23751.n. [Drilling Fluids]
2376The Oslo and Paris Commission, formerly known as PARCOM. The commission is a group of experts who advise North Sea countries on environmental policy and legislation. OSPAR has been influential in establishing North Sea legislation on drilling fluids that has served as the model for other operating areas. OSPAR has published lists of environmentally acceptable and unacceptable products, referred to as the "green," "grey" and "black" lists. The Green or A list consists of products posing relatively little harm to the environment (specifically the marine environment). Examples include inert minerals such as bentonite, inorganic salts that are common constituents of seawater such as sodium and potassium chloride, and simple organic products such as starch and carboxymethylcellulose (CMC). The Grey List consists of products 'requiring strong regulatory control' and includes heavy metals such as zinc, lead and chromium. The Black list covers products considered unsuitable for discharge and includes mercury, cadmium and 'persistent oils and hydrocarbons of a petroleum origin.' The inclusion of hydrocarbons in the black list has been the driving force behind the reduction of oil discharges in the North Sea and elsewhere and has serious implications for the use of oil and synthetic fluids.
2377bioaccumulation, HSE
2378black list, gray list, green list, grey list
2379PARCOM
2380--
2381offset vertical seismic profile
23821.n. [Geophysics]
2383A type of vertical seismic profile in which the source is located at an offset from the drilling rig during acquisition. This allows imaging to some distance away from the wellbore.
2384acquisition, source, vertical seismic profile
2385None
2386None
2387--
2388oil well
23891.n. [Well Testing]
2390A producing well with oil as its primary commercial product. Oil wells almost always produce some gas and frequently produce water. Most oil wells eventually produce mostly gas or water.
2391None
2392None
2393None
2394--
2395open flow potential
23961.n. [Well Completions]
2397The calculated maximum flow rate that a system may provide in the absence of restrictions. The term may be qualified as relating to a specific zone, such as a perforated interval or be used in referring to the production capability of the well.
2398None
2399None
2400None
2401--
2402open flow potential
24032.n. [Well Testing]
2404The theoretical flow capacity of gas wells if the bottomhole pressure could be reduced to atmospheric pressure. Test procedures to determine the AOF (Atmospheric Open-Flow) potential were often prescribed by law and enforced by state agencies. The open-flow potential capacity of the well was then used to determine the maximum rate that the gas well would be allowed to produce into a pipeline. During that period when there was an excessive amount of gas available for sale, this approach allowed an orderly method of allocating production rights to operators. The methodology is still used in some areas.The test required use of multiple rates, usually three or four, with measurement or calculation of the bottomhole pressure at the end of each flow period. The values of the difference between the square of the average reservoir pressure and the square of the bottomhole pressure were computed for each flow rate. These values were then plotted on the y-axis of a log-log plot versus the rate on the x-axis. The value of the open-flow potential is obtained by extrapolating the best straight line to the value of the average reservoir pressure squared minus atmospheric pressure squared, and then reading the corresponding rate off the x-axis.
2405gas-well deliverability, reservoir pressure
2406None
2407None
2408--
2409ovality limit
24101.n. [Well Workover and Intervention]
2411The maximum distortion permitted on the cross-sectional profile of a coiled tubing string. The mechanical performance of oval tubing deteriorates as the degree of ovality increases. The most critical effect is the ability of the tube to resist collapse under differential pressure. String ovality limits are generally determined by the maximum diameter that can pass through the primary pressure-control equipment. In high-pressure operations, the ovality limits will generally be reduced to maintain an adequate safety margin against string collapse.
2412coiled tubing string, differential pressure
2413None
2414None
2415--
2416offset vsp
24171.n. [Geophysics]
2418Abbreviation for offset vertical seismic profile, a type of vertical seismic profile in which the source is located at an offset from the drilling rig during acquisition. This allows imaging to some distance away from the wellbore.
2419acquisition, source, vertical seismic profile
2420None
2421None
2422--
2423oil wet
24241.adj. [Formation Evaluation, Enhanced Oil Recovery]
2425Pertaining to the preference of a solid to be in contact with an oil phase rather than a water or gas phase. Oil-wet rocks preferentially imbibe oil. Generally, polar compounds or asphaltenes deposited from the crude oil onto mineral surfaces cause the oil-wet condition. Similar compounds in oil-base mud also can cause a previously water-wet rock to become partially or totally oil-wet.
2426drainage, imbibition, water-wet, wettability
2427None
2428None
2429--
2430openhole
24311.n. [Drilling]
2432The uncased portion of a well. All wells, at least when first drilled, have openhole sections that the well planner must contend with. Prior to running casing, the well planner must consider how the drilled rock will react to drilling fluids, pressures and mechanical actions over time. The strength of the formation must also be considered. A weak formation is likely to fracture, causing a loss of drilling mud to the formation and, in extreme cases, a loss of hydrostatic head and potential well control problems. An extremely high-pressure formation, even if not flowing, may have wellbore stability problems. Once problems become difficult to manage, casing must be set and cemented in place to isolate the formation from the rest of the wellbore. While most completions are cased, some are open, especially in horizontal or extended-reach wells where it may not be possible to cement casing efficiently.
2433barefoot, blowout, borehole, caliper log, casing point, cementing, completion, packer, tight hole, well control
2434None
2435None
2436--
2437overbalance
24381.n. [Drilling]
2439The amount of pressure (or force per unit area) in the wellbore that exceeds the pressure of fluids in the formation. This excess pressure is needed to prevent reservoir fluids (oil, gas, water) from entering the wellbore. However, excessive overbalance can dramatically slow the drilling process by effectively strengthening the near-wellbore rock and limiting removal of drilled cuttings under the bit. In addition, high overbalance pressures coupled with poor mud properties can cause differential sticking problems. Because reservoir pressures vary from one formation to another, while the mud is relatively constant density, overbalance varies from one zone to another.
2440cuttings, differential sticking
2441None
2442Antonyms:underbalance
2443--
2444offset well
24451.n. [Drilling]
2446An existing wellbore close to a proposed well that provides information for planning the proposed well. In planning development wells, there are usually numerous offsets, so a great deal is known about the subsurface geology and pressure regimes. In contrast, rank wildcats have no close offsets, and planning is based on interpretations of seismic data, distant offsets and prior experience. High-quality offset data are coveted by competent well planners to optimize well designs. When lacking offset data, the well planner must be more conservative in designing wells and include more contingencies.
2447bit record, drilling procedure, wildcat
2448offset
2449None
2450--
2451oil base mud
24521.n. [Drilling Fluids]
2453An invert-emulsion mud, or an emulsion whose continuous phase is oil. In the past, the term referred to an oil mud containing less than about 5 vol.% water. This definition, at the time, distinguished mud with less than 5 vol.% water from invert-emulsion oil muds, which had more than 5 vol.% water. Today, this distinction is not practical because most commercial oil muds can be formulated with more or less than 5 vol.% water using essentially the same types of products.
2454aliphatic compound, aniline point test, electrical stability test, invert emulsion, oil content, oil mud, spotting fluid, syn, synthetic-base fluid
2455invert-emulsion oil mud
2456None
2457--
2458openhole completion
24591.n. [Well Completions]
2460A well completion that has no casing or liner set across the reservoir formation, allowing the produced fluids to flow directly into the wellbore. This type of completion suffers the major disadvantage that the sandface is unsupported and may collapse. Also, without any casing or liner installed, selective treatments or remedial work within the reservoir section are more difficult.
2461None
2462barefoot completion
2463None
2464--
2465overflush
24661.n. [Well Workover and Intervention]
2467A specially prepared fluid used to displace matrix acid treatments away from the wellbore at the conclusion of a stimulation treatment. The overflush is typically formulated from a weak acid solution or brine to maintain a low pH environment in the near-wellbore formation that prevents the precipitation of reaction products as the treatment fluids are flowed back.The overflush is normally a weak acid or brine pumped behind the main treating fluid (mixture of hydrofluoric [HF] and hydrochloric [HCl] or organic acids).The overflush has several purposes:·	displacement of the nonreacted mud acid into the formation.·	displacement of mud-acid reaction by-products such as amorphous silica. The minimum overflush volume should have at least 3 ft [1 m] of radial penetration inside the formation to displace potential problems away from the critical matrix.·	removal of potential oil-wet relative-permeability problems caused by some corrosion inhibitors.
2468matrix stimulation, mud acid, precipitate, preflush
2469None
2470None
2471--
2472oil and gas separator
24731.n. [Production Facilities]
2474A vessel that separates the well fluids into gas and total liquid. A two-phaseseparatorcan be horizontal, vertical or spherical. The liquid (oil,emulsion) leaves the vessel at the bottom through a level-control or dump valve. The gas leaves the vessel at the top, passing through amistextractor to remove the small liquid droplets in the gas.Separators can be categorized according to their operatingpressure. Low-pressure units handle pressures of 10 to 180 psi [69 to 1,241 kPa].Medium-pressure separators operate from 230 to 700 psi [1,586 to 4,826 kPa]. High-pressure units handle pressures of 975 to 1,500 psi [6,722 to 10,342 kPa].Gravitysegregation is the main force that accomplishes the separation, which means the heaviest fluid settles to the bottom and the lightest fluid rises to the top. Additionally, inside the vessel, the degree of separation between gas and liquid will depend on the separator operating pressure, theresidence timeof the fluid mixture and the type of flow of the fluid.Turbulent flowallows more bubbles to escape thanlaminar flow.
2475horizontal separator, mist extractor, separator, spherical separator, stage separation, vertical separator
2476None
2477None
2478--
2479oil emulsion mud
24801.n. [Drilling Fluids]
2481A water-base<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/d/drilling_fluid.aspx">drilling fluidthat contains dispersed oil or synthetic<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/h/hydrocarbon.aspx">hydrocarbonas an<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/i/internal_phase.aspx">internal phase. Early<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/e/emulsion.aspx">emulsionmuds used diesel or<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/c/crude_oil.aspx">crude oildispersed into<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/a/alkaline.aspx">alkalinewater-base muds. Synthetic liquids are now being substituted for oils in emulsion muds. Water-base muds containing certain synthetic liquids can be discharged in the Gulf of Mexico because they are environmentally safe and pass the<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/e/epa.aspx">EPAstatic<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/s/sheen_test.aspx">sheen testand<a href="http://cms.glossary.oilfield.slb.com/sitecore/shell/Controls/Rich%20Text%20Editor//en/Terms/m/mysid_shrimp.aspx">mysid shrimptoxicity tests.Reference: Rogers WF: "Oil-in-Water Emulsion Muds," inComposition and Properties of Oil Well Drilling Fluids, 3rd ed. Houston, Texas, USA: Gulf Publishing Company, 1963.
2482bioassay, carboxymethylcellulose, HLB number, hydrophile-lipophile balance number, interfacial tension, invert emulsion, lignin, lignosulfonate, milk emulsion mud, NPDES, oil-in-water emulsion, olefinic hydrocarbon, polyolefin, starch, surface tension, synthetic-base fluid, water-base drilling fluid, water-mud emulsifier
2483None
2484emulsion mud, oil emulsion mud
2485--
2486openhole packer
24871.n. [Well Completions]
2488A type of packer designed for use in openhole applications such as drillstem testing. Openhole packers are typically configured with one large element that can be deformed easily to contact the uneven formation surface, yet retain strength and sufficient integrity to withstand the anticipated differential pressures.
2489drillstem test, packer
2490None
2491None
2492--
2493overmature
24941.adj. [Geology]
2495Pertaining to a hydrocarbon source rock that has generated as much hydrocarbon as possible and is becoming thermally altered.
2496diagenesis, generation, hydrocarbon, maturity, metamorphism, source rock
2497post mature
2498Antonyms:immature
2499--
2500oil base mud
25011.n. [Drilling Fluids]
2502An invert-emulsion mud, or an emulsion whose continuous phase is oil. In the past, the term referred to an oil mud containing less than about 5 vol.% water. This definition, at the time, distinguished mud with less than 5 vol.% water from invert-emulsion oil muds, which had more than 5 vol.% water. Today, this distinction is not practical because most commercial oil muds can be formulated with more or less than 5 vol.% water using essentially the same types of products.
2503None
2504None
2505oil-base mud
2506--
2507oilfield
25081.adj. [Geology]
2509Pertaining to an oil field, an accumulation, pool or group of pools of oil in the subsurface. An oil field consists of a reservoir in a shape that will trap hydrocarbons and that is covered by an impermeable or sealing rock. Typically, industry professionals use the term with an implied assumption of economic size.
2510accumulation, field, hydrocarbon, oil pool, reservoir, seal, trap
2511None
2512None
2513--
2514oilfield
25152.adj. [Geology]
2516Pertaining to the surface area above a subsurface oil accumulation.
2517accumulation, field, hydrocarbon, oil field, oil pool, reservoir, seal
2518None
2519None
2520--
2521operating gas lift valve oglv
25221.n. [Well Completions]
2523The lowermost gas-lift valve in a gas-lift completion through which the lift gas is injected during normal production. During startup, the upper gas-lift valves open in sequence, from the top down, to enable the tubing fluids to be displaced. At predetermined pressures, each of the upper valves closes to eventually route all lift gas through the operating valve, which is placed at the optimal depth for the reservoir and completion conditions.
2524gas lift
2525None
2526None
2527--
2528overpressure
25291.n. [Geology]
2530Subsurface pressure that is abnormally high, exceeding hydrostatic pressure at a given depth. The term geopressure is commonly, and incorrectly, used synonymously. Abnormally high pore pressure can occur in areas where burial of fluid-filled sediments is so rapid that pore fluids cannot escape, so the pressure of the pore fluids increases as overburden increases. Drilling into overpressured strata can be hazardous because overpressured fluids escape rapidly, so careful preparation is made in areas of known overpressure.
2531abnormal pressure, formation pressure, geopressure, geostatic pressure, hydrostatic pressure, overburden, pore pressure
2532None
2533Antonyms:underpressure
2534--
2535oil emulsion mud
25361.n. [Drilling Fluids]
2537A water-base drilling fluid that contains dispersed oil or synthetic hydrocarbon as an internal phase. Early emulsion muds used diesel or crude oil dispersed into alkaline water-base muds. Synthetic liquids are now being substituted for oils in emulsion muds. Water-base muds containing certain synthetic liquids can be discharged in the Gulf of Mexico because they are environmentally safe and pass the EPA static sheen test and mysid shrimptoxicity tests.Reference:Rogers WF: "Oil-in-Water Emulsion Muds," inComposition and Properties of Oil Well Drilling Fluids, 3rd ed. Houston, Texas, USA: Gulf Publishing Company, 1963.
2538bioassay, carboxymethylcellulose, HLB number, hydrophile-lipophile balance number, interfacial tension, invert emulsion, lignin, lignosulfonate, milk emulsion mud, NPDES, oil-in-water emulsion, olefinic hydrocarbon, polyolefin, starch, surface tension, synthetic-base fluid, water-base drilling fluid, water-mud emulsifier
2539None
2540emulsion mud, oil-emulsion mud
2541--
2542oil mud emulsifier
25431.n. [Drilling Fluids]
2544A chemical used in preparation and maintenance of an oil- or synthetic-base drilling fluid that forms a water-in-oil emulsion (invert emulsion). An oil-mud emulsifier lowers the interfacial tension between oil and water, which allows stable emulsions with small drops to be formed. Historically, oil-mud emulsifiers have been classified as primary and secondary. Secondary emulsifiers are generally not used alone to make a stable oil mud. Emulsifiers can be calcium fatty-acid soaps made from various fatty acids and lime, or derivatives such as amides, amines, amidoamines and imidazolines made by reactions of fatty acids and various ethanolamine compounds. These emulsifiers surround water droplets, like an encapsulating film, with the fatty acid component extending into the oil phase. Emulsifier molecules that cannot fit around drops form clusters (micelles) in the oil phase or adsorb onto solids. Oil-mud emulsion drops each behave like a small osmotic cell. The emulsifier around the drops acts like a semipermeable membrane through which water can move but ions cannot pass. Thus, oil muds have the special capability (which water muds do not have) to control water transfer to and from the drops simply by adjusting salinity within the water phase of the oil mud.
2545balanced-activity oil mud, colloid, emulsion, fatty acid, fatty-acid soap, HLB number, hydrophile-lipophile balance number, interfacial tension, invert-emulsion oil mud, low-colloid oil mud, oil mud, osmosis, soap, water-in-oil emulsion
2546None
2547None
2548--
2549operator
25501.n. [Drilling]
2551The company that serves as the overall manager and decision-maker of a drilling project. Generally, but not always, the operator will have the largest financial stake in the project. At the successful completion of logging the target zones, the decision to complete or plug and abandon generally has partner input and potential override clauses. As far as the drilling contractor and service companies are concerned, the designated operator is paying for the entire operation, and the operator is responsible for recouping some of that expense from the partners.
2552drilling contractor, plug and abandon
2553None
2554None
2555--
2556operator
25572.n. [Oil and Gas Business]
2558The owner of the right to drill or produce a well, or the entity contractually charged with drilling of a test well and production of subsequent wells.
2559None
2560None
2561operator
2562--
2563overriding royalty
25641.n. [Oil and Gas Business]
2565A percentage share of production, or the value derived from production, which is free of all costs of drilling and producing, and is created by the lessee or working interest owner and paid by the lessee or working interest owner.
2566working interest
2567None
2568None
2569--
2570oil field
25711.n. [Geology]
2572An accumulation, pool or group of pools of oil in the subsurface. An oil field consists of a reservoir in a shape that will trap hydrocarbons and that is covered by an impermeable or sealing rock. Typically, industry professionals use the term with an implied assumption of economic size.
2573accumulation, field, hydrocarbon, oil pool, oilfield, reservoir, seal, trap
2574None
2575None
2576--
2577oil field
25782.n. [Geology]
2579The surface area above a subsurface oil accumulation is called an oil field.
2580accumulation, field, hydrocarbon, oil pool, oilfield, reservoir, seal
2581None
2582None
2583--
2584oil water contact
25851.n. [Geology]
2586A bounding surface in a reservoir above which predominantly oil occurs and below which predominantly water occurs. Although oil and water are immiscible, the contact between oil and water is commonly a transition zone and there is usually irreducible water adsorbed by the grains in the rock and immovable oil that cannot be produced. The oil-water contact is not always a flat horizontal surface, but instead might be tilted or irregular.
2587downdip, fluid contact, gas-oil contact, gas-water contact, immiscible, miscible, reservoir, updip
2588None
2589OWC
2590--
2591optical probe
25921.n. [Production Logging]
2593A small sensor in a production logging tool that distinguishes the type of fluid in its vicinity as it is moved up and down a production well. The optical probe is sensitive to the optical index of the fluid in front of the probe. It can distinguish easily between gas and liquid, and less easily between oil and water. Light is sent from a source down a fiber-optic cable to the tip of the probe, and reflected back to a sensor, which converts it into an electrical signal. Gas, with a low optical index, reflects a significant amount of light and gives a large signal, while liquids give low signals.As with other local probes, the output is set to be nearly digital, so that the percentage of the time that the probe sees gas is a direct measure of gas holdup in front of the probe. By using several probes, it is possible to obtain the average holdup and an image of the flow structure across the well.
2594bubble count, electric probe, flow structure, holdup image, local holdup, production log, velocity image
2595None
2596None
2597--
2598overshot
25991.n. [Well Workover and Intervention]
2600A downhole tool used in fishing operations to engage on the outside surface of a tube or tool. A grapple, or similar slip mechanism, on the overshot grips the fish, allowing application of tensile force and jarring action. If the fish cannot be removed, a release system within the overshot allows the overshot to be disengaged and retrieved.
2601None
2602None
2603None
2604--
2605oil formation volume factor
26061.n. [Well Testing]
2607Oil and dissolved gas volume at reservoir conditions divided by oil volume at standard conditions. Since most measurements of oil and gas production are made at the surface, and since the fluid flow takes place in the formation, volume factors are needed to convert measured surface volumes to reservoir conditions. Oil formation volume factors are almost always greater than 1.0 because the oil in the formation usually contains dissolved gas that comes out of solution in the wellbore with dropping pressure.
2608None
2609None
2610None
2611--
2612oil wet
26131.adj. [Formation Evaluation, Enhanced Oil Recovery]
2614Pertaining to the preference of a solid to be in contact with an oil phase rather than a water or gas phase. Oil-wet rocks preferentially imbibe oil. Generally, polar compounds or asphaltenes deposited from the crude oil onto mineral surfaces cause the oil-wet condition. Similar compounds in oil-base mud also can cause a previously water-wet rock to become partially or totally oil-wet.
2615drainage, imbibition, water-wet, wettability
2616None
2617None
2618--
2619organic acid
26201.n. [Enhanced Oil Recovery]
2621A type of organic fluid, such as acetic or formic acid, used in oil and gas well-stimulation treatments. The use of inhibited HCl at elevated temperatures is limited to relatively short exposure times because of the risk of increased corrosion. Inhibited organic acids are much less reactive with metals than are HCl or mixtures of HCl and HF. For this reason, organic acids are commonly used successfully at high bottomhole temperatures or when long contact times between acid and pipe are needed, such as during perforating. Organic acids also are used to protect exotic alloys, such as aluminum or chrome-plated parts.
2622acetic acid, formic acid
2623None
2624None
2625--
2626owc
26271.n. [Geology]
2628Abbreviation for oil-water contact, abounding surface in a reservoir above which predominantly oil occurs and below which predominantly water occurs. Although oil and water are immiscible, the contact between oil and water is commonly a transition zone and there is usually irreducible water adsorbed by the grains in the rock and immovable oil that cannot be produced. The oil-water contact is not always a flat horizontal surface, but instead might be tilted or irregular.
2629downdip, fluid contact, gas-oil contact, gas-water contact, immiscible, miscible, reservoir, updip
2630None
2631oil-water contact
2632--
2633oil mining
26341.n. [Enhanced Oil Recovery]
2635A strip-mining process involving the removal and subsequent processing of tar sand from shallow reservoirs containing heavy, viscous oil. The oil is mostly bitumen and does not flow at reservoir conditions. For strip mining to be economic, the reservoir must be shallow and have high oil saturation. Strip mining is energy intensive, both in mining the tar sand and in its subsequent processing. Large amounts of waste material, called gangue, are produced. Companies are usually required to landscape the area when mining is completed.
2636None
2637None
2638None
2639--
2640olefinic hydrocarbon
26411.n. [Drilling Fluids]
2642The group of hydrocarbon compounds that has one or more double or triple bonds between carbon atoms in the linear chain. Ethylene, C2H4, is the smallest olefin. Synthetic olefinic hydrocarbons are made by polymerization of ethylene under catalytic conditions. They are used in synthetic-base mud and as lubricants for water muds.
2643aliphatic compound, aromatic hydrocarbon, emulsion mud, isomerized olefin, linear alphaolefin, naphthenic hydrocarbon, paraffinic hydrocarbon, polyalphaolefin, syn, synthetic-base fluid, synthetic-base mud
2644None
2645None
2646--
2647organic deposit
26481.n. [Enhanced Oil Recovery]
2649A type of damage in which heavy hydrocarbons precipitate when temperature or pressure is reduced. These deposits are commonly located in the tubing, gravel pack and perforations, or inside the formation. The injection of cold treating fluids promotes the formation of organic deposits.Organic deposits such as paraffins or asphaltenes are resolubilized using aromatic organic solvents such as toluene or xylene. Small amounts of alcohol help to further dissolve asphaltenes.
2650damage, sludge
2651None
2652None
2653--
2654oxide closure model
26551.n. [Formation Evaluation]
2656A model for converting relative elemental yields from a pulsed neutron spectroscopy log to absolute weight concentrations using the assumption that the sum of all oxides in the rock matrix is 1. The model is based on the observation that, with few exceptions, sedimentary minerals are oxides, so that the sum of the dry weight percent of all oxides must be 100%. The weight percent of an oxide can be calculated from the dry weight percent of the cation by knowing the chemical formula (for example, SiO2 from Si).The absolute dry weight percent, W, of element i is given by Wi = F * Yi / Si where F is the unknown normalization factor, Yi is the measured spectral gamma ray yield and Si is the tool sensitivity to that element, measured in the laboratory. The dry weight percent of the oxide is then Oi = F* Xi * Yi / Si where Xi is the oxide association factor, given by the chemical formula. Since the sum of all Oi equals 1, it is possible to calculate F and determine each Wi .
2657elemental capture spectroscopy, geochemical log, natural gamma ray spectroscopy
2658None
2659None
2660--
2661oil mud
26621.n. [Drilling Fluids]
2663A mud in which the external phase is a product obtained from an oil, such as diesel oil or mineral oil.
2664aniline point test, attapulgite, brine, bypassed mud, calcium chloride, calcium test, Chenevert Method, chloride test, coalescence, colloid, creaming, diesel-oil mud, dispersion, drilling fluid, electrical stability test, fatty acid, fatty-acid soap, flash point, hectorite, high-pressure, high-temperature viscometer, hydrophile-lipophile balance number, hygrometer, inhibit, inhibitive mud, interfacial tension, invert-emulsion oil mud, lignite, oil-base mud, oil-mud emulsifier, oil/water ratio, organophilic, organophilic lignite, pour point, rheology modifier, shale, sheen test, slurry, surface tension, suspended solids, synthetic-base mud, synthetic/water ratio, water-in-oil emulsion
2665None
2666None
2667--
2668oil mud
26692.n. [Drilling Fluids]
2670More generally, a mud system that has any type of nonaqueous fluid as the external phase. This definition would include the newer variety of oil muds that are more exactly defined as synthetic-base muds. Synthetic mud is analogous to oil mud.
2671diesel-oil mud, invert-emulsion oil mud, oil-base mud, syn, synthetic-base mud
2672None
2673None
2674--
2675oligomer
26761.n. [Drilling Fluids]
2677A low-molecular-weight polymer typically with two to five monomer units.
2678isomerized olefin, linear alphaolefin, polyalphaolefin, polyol, rheology modifier, syn, synthetic-base fluid, vinyl polymer
2679None
2680None
2681--
2682organophilic lignite
26831.n. [Drilling Fluids]
2684A lignite that has been coated with a chemical that renders it dispersible in oil. The treatment is usually accomplished with a type of quaternary amine compound.
2685invert-emulsion oil mud, invert-emulsion oil mud, lignite, lyophilic, oil mud, organophilic, quaternary amine
2686None
2687None
2688--
2689oxide closure model
26901.n. [Formation Evaluation]
2691A model for converting relative elemental yields from a pulsed neutron spectroscopy log to absolute weight concentrations using the assumption that the sum of all oxides in the rock matrix is 1. The model is based on the observation that, with few exceptions, sedimentary minerals are oxides, so that the sum of the dry weight percent of all oxides must be 100%. The weight percent of an oxide can be calculated from the dry weight percent of the cation by knowing the chemical formula (for example, SiO2 from Si).The absolute dry weight percent, W, of element i is given by Wi = F * Yi / Si where F is the unknown normalization factor, Yi is the measured spectral gamma ray yield and Si is the tool sensitivity to that element, measured in the laboratory. The dry weight percent of the oxide is then Oi = F* Xi * Yi / Si where Xi is the oxide association factor, given by the chemical formula. Since the sum of all Oi equals 1, it is possible to calculate F and determine each Wi .
2692elemental capture spectroscopy, geochemical log, natural gamma ray spectroscopy
2693None
2694None
2695--
2696oil on cuttings
26971.n. [Drilling Fluids]
2698The oil content of cuttings, normally expressed as grams of oil adsorbed per kilogram of dry cuttings. The value has been used as the basis for discharge regulations for oil-base muds in several operating areas.
2699None
2700None
2701OOC
2702--
2703onlap
27041.n. [Geology]
2705The termination of shallowly dipping, younger strata against more steeply dipping, older strata, or the termination of low-angle reflections in seismic data against steeper reflections. Onlap is a particular pattern of reflections in seismic data that, according to principles of sequence stratigraphy, occurs during periods of transgression.
2706apparent dip, downlap, pinch-out, retrogradation, sequence stratigraphy, transgression
2707None
2708None
2709--
2710orifice valve
27111.n. [Well Completions]
2712A type of valve, typically found on small-diameter pipework, that incorporates an orifice or flow-restriction device to control fluid flow.
2713None
2714None
2715None
2716--
2717oxygen activation
27181.n. [Production Logging]
2719A phenomenon exploited for the purpose of detecting and quantifying the flow of water in or around a borehole based on oxygen activation. Oxygen (16O) can be activated by high-energy neutrons to produce an isotope of nitrogen (16N), which decays back to oxygen with a half-life of 7.1 seconds and emits an easily detected gamma ray of 6.13 MeV. The neutrons are supplied by the generator of a pulsed-neutron spectroscopy tool. The gamma rays are counted in detectors placed above the tool, for upward flow, or below it for downward flow.Various techniques have been developed to analyze the count rates in terms of water velocity, flow rate and distance from tool. The earliest methods were based of the ratio of the counts from two detectors. Stationary oxygen and other background signals are eliminated by calibration in a known zone of zero flow, by counting only in a window near 6.13 MeV, or by optimizing the detector spacings. More recently, impulse-activation techniques have been introduced. While they require the tool to be stationary, they are generally more accurate.
2720activation log, neutron capture, neutron generator, pulsed neutron spectroscopy measurement
2721None
2722None
2723--
2724pa
27251.vb. [Drilling]
2726To prepare a well to be closed permanently, usually after either logs determine there is insufficient hydrocarbon potential to complete the well, or after production operations have drained the reservoir. Different regulatory bodies have their own requirements for plugging operations. Most require that cement plugs be placed and tested across any open hydrocarbon-bearing formations, across all casing shoes, across freshwater aquifers, and perhaps several other areas near the surface, including the top 20 to 50 ft [6 to 15 m] of the wellbore. The well designer may choose to set bridge plugs in conjunction with cement slurries to ensure that higher density cement does not fall in the wellbore. In that case, the bridge plug would be set and cement pumped on top of the plug through drillpipe, and then the drillpipe withdrawn before the slurry thickened.
2727None
2728None
2729plug and abandon
2730--
2731petroleum system
27321.n. [Geology]
2733Geologic components and processes necessary to generate and store hydrocarbons, including a mature source rock, migration pathway, reservoir rock, trap and seal. Appropriate relative timing of formation of these elements and the processes of generation, migration and accumulation are necessary for hydrocarbons to accumulate and be preserved. The components and critical timing relationships of a petroleum system can be displayed in a chart that shows geologic time along the horizontal axis and the petroleum system elements along the vertical axis. Exploration plays and prospects are typically developed in basins or regions in which a complete petroleum system has some likelihood of existing.
2734bitumen, cap rock, critical moment, geochemistry, geologic time scale, kerogen, play, preservation, prospect, sedimentary basin, source rock
2735None
2736None
2737--
2738polymer flooding
27391.n. [Enhanced Oil Recovery]
2740An enhanced oil recovery technique using water viscosified with soluble polymers. Viscosity is increased until the mobility of the injectant is less than that of the oil phase in place, so the mobility ratio is less than unity. This condition maximizes oil-recovery sweep efficiency, creating a smooth flood front without viscous fingering. Polymer flooding is also applied to heterogeneous reservoirs; the viscous injectant flows along high-permeability layers, decreasing the flow rates within them and enhancing sweep of zones with lower permeabilities. The two polymers that are used most frequently in polymer flooding are partially hydrolyzed polyacrylamide and xanthan.
2741micellar-polymer flooding, mobility ratio
2742None
2743None
2744--
2745pressure transient well test
27461.n. [Reservoir Characterization]
2747A means of assessing reservoir performance by measuring flow rates and pressures under a range of flowing conditions and then applying the data to a mathematical model. In most well tests, a limited amount of fluid is allowed to flow from the formation being tested. The formation is isolated behind cemented casing and perforated at the formation depth or, in openhole, the formation is straddled by a pair of packers that isolate the formation. During the flow period, the pressure at the formation is monitored over time. Then, the formation is closed (or shut in) and the pressure monitored at the formation while the fluid within the formation equilibrates. The analysis of these pressure changes can provide information on the size and shape of the formation as well as its ability to produce fluids.
2748None
2749None
2750None
2751--
2752pac
27531.n. [Drilling Fluids]
2754A cellulose derivative similar in structure, properties and usage in drilling fluids to carboxymethylcellulose. PAC is considered to be a premium product because it typically has a higher degree of carboxymethyl substitution and contains less residual NaCl than technical grade carboxymethylcellulose, although some PACs contain considerable NaCl.
2755None
2756None
2757polyanionic cellulose
2758--
2759petrologic
27601.adj. [Geology]
2761Pertaining to the macroscopic features of rocks, such as their occurrence, origin and history, structure (usually by examining outcrops in thefield), and their texture and composition (by studying smaller samples more closely).
2762petrography
2763None
2764None
2765--
2766polymer plug
27671.n. [Well Workover and Intervention]
2768A volume of polymer slurry placed in a wellbore, which, in time and under the correct temperature conditions, will develop to provide a high-viscosity platform on which a cement plug can be placed. Polymer plugs are typically used when a cement plug must be set accurately within the wellbore, The viscous material prevents the dense cement slurry from fingering through the lighter wellbore fluid during placement, helping to ensure that cement is placed over the desired interval.
2769None
2770None
2771None
2772--
2773pressure transient well tests
27741.n. [Well Testing]
2775Well tests in which pressure is recorded as a function of time and interpreted using various analysis methods. These include buildup tests and drawdown tests in production wells and falloff tests in injection wells. Pressure-transient well-test analysis procedures are based on classical mathematical relationships between flow rate, pressure and time, which are directly analogous to the theory of heat transfer.
2776buildup test, drawdown test, falloff test, injection well
2777None
2778None
2779--
2780pack off
27811.vb. [Drilling]
2782To plug the wellbore around a drillstring. This can happen for a variety of reasons, the most common being that either the drilling fluid is not properly transporting cuttings and cavings out of the annulus or portions of the wellbore wall collapse around the drillstring. When the well packs off, there is a sudden reduction or loss of the ability to circulate, and high pump pressures follow. If prompt remedial action is not successful, an expensive episode of stuck pipe can result. The term is also used in gravel packing to describe the act of placing all the sand or gravel in the annulus.
2783annulus, circulate, cuttings, stuck pipe
2784None
2785None
2786--
2787pack off
27882.n. [Drilling]
2789A flexible, usually elastomeric sealing element and housing used to seal an irregular surface such as a wireline.
2790None
2791None
2792None
2793--
2794pack off
27953.vb. [Well Completions]
2796To effect hydraulic isolation, either with a sealing device, such as a packer, or with a specialized plastic or fluid, such as a sealing compound.
2797packer, seal assembly
2798None
2799None
2800--
2801petrology
28021.n. [Geology]
2803The study of macroscopic features of rocks, such as their occurrence, origin and history, and structure (usually by examining outcrops in the field) and their texture and composition (by studying smaller samples more closely).
2804petrography
2805None
2806None
2807--
2808polyolefin
28091.n. [Drilling Fluids]
2810Also known as isomerized olefin or IO, a synthetic hydrocarbon liquid made by the polymerization of ethylene,H2C=CH2. IOs are one of several synthetic fluids that have recently been used as base for synthetic-base muds and in other applications where refined oils might otherwise be used except for HSE concerns. IOs are linear structures that have their olefin double bond in the center of the chain length. They are made by isomerization of linear alphaolefins (LAO), which have their double bond at the end of the chain. Because the olefin bond is in the central area of the chain, the physical properties of IOs are different (for example, they are generally lower viscosity) compared with the LAOs from which they are made.
2811diesel-oil mud, emulsion mud, linear alphaolefin, olefinic hydrocarbon, oligomer, polyalphaolefin, polymer, synthetic-base fluid, synthetic-base mud
2812IO, isomerized olefin
2813None
2814--
2815pressure drawdown analysis
28161.n. [Well Testing]
2817The analysis of pressure-transient behavior observed while the well is flowing. Results are generally much less accurate than those from pressure buildup tests because the bottomhole pressure fluctuates rapidly with even slight changes in the surface flow rate. Therefore, pressure buildup tests are much preferred, and analysis of drawdown test data is usually relegated to backup status unless the buildup data are flawed.
2818bottomhole pressure, drawdown test, pressure buildup
2819None
2820None
2821--
2822packer
28231.n. [Drilling]
2824A device that can be run into a wellbore with a smaller initial outside diameter that then expands externally to seal the wellbore. Packers employ flexible, elastomeric elements that expand. The two most common forms are the production or test packer and the inflatable packer. The expansion of the former may be accomplished by squeezing the elastomeric elements (somewhat doughnut shaped) between two plates, forcing the sides to bulge outward. The expansion of the latter is accomplished by pumping a fluid into a bladder, in much the same fashion as a balloon, but having more robust construction. Production or test packers may be set in cased holes and inflatable packers are used in open or cased holes. They may be run on wireline, pipe or coiled tubing. Some packers are designed to be removable, while others are permanent. Permanent packers are constructed of materials that are easy to drill or mill out.
2825cased hole, coiled tubing, completion, differential pressure, drillstem test, milling, openhole, production packer
2826None
2827None
2828--
2829packer
28302.n. [Well Completions]
2831A downhole device used in almost every completion to isolate the annulus from the production conduit, enabling controlled production, injection or treatment. A typical packer assembly incorporates a means of securing the packer against the casing or liner wall, such as a slip arrangement, and a means of creating a reliable hydraulic seal to isolate the annulus, typically by means of an expandable elastomeric element. Packers are classified by application, setting method and possible retrievability.
2832None
2833None
2834None
2835--
2836petrophysical model
28371.n. [Reservoir Characterization]
2838A process or procedure used to interpret petrophysical (usually wireline log) data. Usually representing a set of equations, algorithms or other mathematical processes, petrophysical models often have multiple routines. For example, a deterministic model might include routines that:calculate the shale volumecalculate total porositycalculate effective porositycalculate water saturationcalculate permeability.Often, the model is calibrated using core, production, test and other data sets. Although many software packages contain ready-built petrophysical models or component routines that can be called upon, many log-analysis problems are unique and require that "built to purpose" models be constructed. Construction of new petrophysical models is normally driven by the data available and the nature of the problem to be solved.
2839None
2840None
2841None
2842--
2843petrophysical model
28442.n. [Reservoir Characterization]
2845A model of a reservoir or a field in which the petrophysical data were the only or the primary data used to construct the model.
2846None
2847None
2848None
2849--
2850polysaccharide
28511.n. [Enhanced Oil Recovery]
2852A carbohydrate composed of many monosaccharides. Polysaccharides increase the viscosity of the water slug that precedes the final water injection. However, they are not frequently used in chemical flooding operations because they generate numerous by-products that can potentially plug filters or well sandfaces, especially when they contact polyvalent cations or bacteria.Polysaccharides are also called biopolymers.
2853mobility buffer, polyacrylamide
2854None
2855None
2856--
2857pressure squared plot
28581.n. [Well Testing]
2859A plot of p2 versus time function used to analyze low-pressure gas-well drawdown and buildup tests. The square term arises from substituting a gas-law equation into the differential equations where required to account for fluid compressibility. This allows an approximation for the differential equations that approaches the linear form required to use the classical solutions of the diffusion equation.
2860buildup test, diffusion equation, drawdown test, fluid compressibility
2861None
2862None
2863--
2864packer flowmeter
28651.n. [Production Logging]
2866A device for measuring in situ the velocity of fluid flow in a production or injection well in which a packer is inflated between the tool housing and the casing wall, causing the total fluid flow to pass inside the tool and over a spinner. The measurement is made with the tool stationary, after borehole fluids have been pumped to inflate the packer. The packer flowmeter was introduced in the mid-1950s. It is a type of diverter flowmeter, but has generally been replaced by petal basket and inflatable diverter flowmeters.
2867basket flowmeter, diverter flowmeter, in situ, inflatable packer, injection well, spinner flowmeter
2868None
2869None
2870--
2871petrophysical rock type
28721.n. [Reservoir Characterization]
2873Rock types that have been classified according to their petrophysical properties, especially properties that pertain to fluid behavior within the rock, such as porosity, capillary pressure, permeabilities, irreducible saturations or saturations. Petrophysical rock types are often calibrated from core and dynamic data, but are usually calculated from wireline logs, where possible, because the wireline logs are generally the only measurements that are available for all wells at all depths. Electrofacies approaches are often used to determine rock types from logs.
2874None
2875None
2876None
2877--
2878pony rod
28791.n. [Production Testing]
2880A rod shorter than usual, usually placed below the polished rod and used to make a rod string of a desired length.
2881None
2882None
2883None
2884--
2885pressure transient analysis
28861.n. [Reservoir Characterization, Well Testing]
2887The analysis of pressure changes over time, especially those associated with small variations in the volume of fluid. In most well tests, a limited amount of fluid is allowed to flow from the formation being tested and the pressure at the formation monitored over time. Then, the well is closed and the pressure monitored while the fluid within the formation equilibrates. The analysis of these pressure changes can provide information on the size and shape of the formation as well as its ability to produce fluids.
2888None
2889None
2890None
2891--
2892packer fluid
28931.n. [Drilling Fluids]
2894A fluid that is left in the annular region of a well between tubing and outer casing above a packer. The main functions of a packer fluid are: (1) to provide hydrostatic pressure in order to lower differential pressure across the sealing element, (2) to lower differential pressure on the wellbore and casing to prevent collapse and (3) to protect metals and elastomers from corrosion.
2895differential pressure, hydrostatic pressure
2896None
2897None
2898--
2899packer fluid
29002.n. [Well Completions]
2901The fluid that remains in the tubing-casing annulus above the packer after the completion has been run and all circulation devices have been isolated. Packer fluids are prepared for the requirements of the given completion. Generally, they should be of sufficient density to control the producing formation, be solids-free and resistant to viscosity changes over long periods of time, and be noncorrosive to the wellbore and completion components.
2902None
2903None
2904None
2905--
2906ph
29071.n. [Drilling Fluids]
2908Hydrogen ion potential, which is the log10 of the reciprocal of hydrogen ion, H+, concentration. Mathematically, pH = log10 (1/[H+]), where [ ] represents mole/L. pH is derived from the ion-product constant of water, which at room temperature is 1 x 10-14 = [H+] x [OH-]. Pure water (at neutral pH) has equal concentrations of its two ions: [H+] = [OH-] = 10-7 mole/L. Log10 1/[H+] is 7, which is the pH of a neutral solution. The pH scale ranges from 0 to 14, and values below 7 are acidic and above 7 are basic.
2909alkaline, alkalinity, alkalinity test, bland coring fluid, bromocresol green, buffer, buffer solution, buffered mud, buffered solution, calcium sulfate, carbon dioxide, carbonate ion, completion fluid, hydrogen sulfide, hydrolysis, pH test, phenolphthalein, phosphate salt, prehydrated bentonite, quebracho, red mud, salt, SAPP, siderite, silicate mud, sodium bicarbonate, sodium carbonate, wastewater cleanup
2910None
2911None
2912--
2913pooling
29141.n. [Oil and Gas Business]
2915The accumulation of smaller tracts of land, the sum total acreage of which are required for a governmental agency to grant a well permit or assign a production quota or allowable to an operator.
2916communitization, unitization
2917None
2918None
2919--
2920pressure transient well tests
29211.n. [Well Testing]
2922Well tests in which pressure is recorded as a function of time and interpreted using various analysis methods. These include buildup tests and drawdown tests in production wells and falloff tests in injection wells. Pressure-transient well-test analysis procedures are based on classical mathematical relationships between flow rate, pressure and time, which are directly analogous to the theory of heat transfer.
2923buildup test, drawdown test, falloff test, injection well
2924None
2925None
2926--
2927packing gland
29281.n. [Well Completions]
2929A device used to seal around a reciprocating or rotating shaft or spindle. A malleable packing compound is forced into place by an adjustable packing nut, or similar arrangement. This enables the seal or packing to be tightened to suit the operating conditions and allows subsequent adjustment to account for wear.
2930None
2931None
2932None
2933--
2934ph test
29351.n. [Drilling Fluids]
2936A drilling-fluid test to measure pH of muds and mud filtrates, usually performed according to API specifications. The pH test uses a pH meter equipped with a glass-membrane measuring electrode and reference electrode, which read from 0 to 14. The preferred pH meter automatically compensates for temperature. Buffer solutions of pH = 4, 7 and 10 are specified for calibration of the meter. Color-matching pH paper and sticks are not recommended except for simple muds.
2937alkalinity, buffer, pH
2938None
2939None
2940--
2941pore gas
29421.n. [Reservoir Characterization, Shale Gas]
2943Also known as interstitial gas, the gas stored in the pore space of a reservoir rock. Measurement of interstitial gas and adsorbed gas, which is the gas accumulated on the surface of another solid material, such as a grain of reservoir rock, allows calculation of gas in place in a reservoir.
2944None
2945interstitial gas
2946None
2947--
2948pressurized mud balance
29491.n. [Drilling Fluids]
2950A device to measure density (weight) of a mud, cement or other liquid or slurry under sufficient pressure that the effect of gas bubbles in the liquid is eliminated. The balance consists of a fixed-volume mud cup on one end of a graduated beam and a counterweight on the other end. The beam has a knife-edge as a balance point and a bubble to show when it is level. The mud cup has a screw-on, sealed cap with a valve in the cap to allow connection of a small piston-type hand pump. Operation of the pressurized balance is identical to an ordinary mud balance after pressurization.
2951gas-cut mud, hydrostatic pressure, mud balance, mud cup, mud weight, slurry
2952None
2953None
2954--
2955packoff
29561.vb. [Drilling]
2957To plug the wellbore around a drillstring. This can happen for a variety of reasons, the most common being that either the drilling fluid is not properly transporting cuttings and cavings out of the annulus or portions of the wellbore wall collapse around the drillstring. When the well packs off, there is a sudden reduction or loss of the ability to circulate, and high pump pressures follow. If prompt remedial action is not successful, an expensive episode of stuck pipe can result. The term is also used in gravel packing to describe the act of placing all the sand or gravel in the annulus.
2958None
2959None
2960pack off
2961--
2962packoff
29632.n. [Drilling]
2964A flexible, usually elastomeric sealing element and housing used to seal an irregular surface such as a wireline.
2965None
2966None
2967pack off
2968--
2969packoff
29703.vb. [Well Workover and Intervention]
2971To effect hydraulic isolation, either with a sealing device, such as a packer, or with a specialized plastic or fluid, such as a sealing compound.
2972None
2973None
2974packoff
2975--
2976phantom
29771.n. [Geophysics]
2978An interpretation of the presumed continuation of an event. In areas of discontinuous, divergent reflectors or incoherent data, drawing phantoms allows the interpreter to generate a map on a discontinuous event.
2979coherence, event, interpretation
2980None
2981None
2982--
2983pore pressure
29841.n. [Geology]
2985The pressure of fluids within the pores of a reservoir, usually hydrostatic pressure, or the pressure exerted by a column of water from the formation's depth to sea level. When impermeable rocks such as shales form as sediments are compacted, their pore fluids cannot always escape and must then support the total overlying rock column, leading to anomalously high formation pressures. Because reservoir pressure changes as fluids are produced from a reservoir, the pressure should be described as measured at a specific time, such as initial reservoir pressure.
2986abnormal pressure, compaction, geopressure, hydrostatic pressure, impermeable, overpressure, permeability, pressure gradient, shale, underpressure, virgin pressure
2987None
2988None
2989--
2990pore pressure
29912.n. [Drilling]
2992The pressure of the subsurfaceformationfluids, commonly expressed as the density of fluid required in the wellbore to balance that pore pressure. A normal pressure gradient might require 9 lbm/galUS[1.08 kg/m3], while an extremely high gradient may need 18 lbm/galUS [2.16 kg/m3] or higher.
2993None
2994None
2995formation pressure, reservoir pressure
2996--
2997pore pressure
29983.n. [Well Completions]
2999The pressure within the reservoir rock. The formation pressure value can be further categorized as relating to flowing well or shut-in conditions.
3000None
3001None
3002formation pressure, reservoir pressure
3003--
3004primary production
30051.n. [Enhanced Oil Recovery, Production Testing]
3006Also known as primary recovery, the first stage of hydrocarbon production, in which natural reservoir energy, such as gasdrive, waterdrive or gravity drainage, displaces hydrocarbons from the reservoir, into the wellbore and up to surface.Initially, the reservoir pressure is considerably higher than the bottomhole pressure inside the wellbore. This high natural differential pressure drives hydrocarbons toward the well and up to surface. However, as the reservoir pressure declines because of production, so does the differential pressure. To reduce the bottomhole pressure or increase the differential pressure to increase hydrocarbon production, it is necessary to implement an artificial lift system, such as a rod pump, an electrical submersible pump or a gas-lift installation. Production using artificial lift is considered primary recovery.The primary recovery stage reaches its limit either when the reservoir pressure is so low that the production rates are not economical, or when the proportions of gas or water in the production stream are too high. During primary recovery, only a small percentage of the initial hydrocarbons in place are produced, typically around 10% for oil reservoirs.
3007artificial lift, enhanced oil recovery, gas-cap drive, gravity drainage, reservoir pressure, reservoir-drive mechanisms, secondary recovery, solution gasdrive, tertiary recovery
3008primary recovery
3009None
3010--
3011pad
30121.n. [Drilling, Production]
3013A temporary drilling site, usually constructed of local materials such as gravel, shell or even wood. For some long-drilling-duration, deep wells, such as the ultradeep wells of western Oklahoma, or some regulatory jurisdictions such as The Netherlands, pads may be paved with asphalt or concrete. After the drilling operation is over, most of the pad is usually removed or plowed back into the ground.
3014multiwell pad
3015None
3016None
3017--
3018pad
30192.n. [Drilling, Production]
3020A fluid used to initiate hydraulic fracturing that does not contain proppant.
3021multiwell pad
3022None
3023None
3024--
3025pad
30263.n. [Formation Evaluation]
3027That part of a wireline logging tool that is pressed firmly against the borehole wall. The pad holds sensors that are focused in one direction and must be as close as possible to the borehole wall. The density detectors and the microresistivity electrodes are examples of sensors that must be placed on pads. Some pads are a rigid part of the logging tool. Others have articulated joints attaching them to the logging tool, with a backup arm to press the pad against the borehole wall.
3028sidewall, sonde, wireline log
3029None
3030None
3031--
3032phase
30331.n. [Geophysics]
3034A description of the motion of, or means of comparison of, periodic waves such as seismic waves. Waves that have the same shape, symmetry and frequency and that reach maximum and minimum values simultaneously are in phase. Waves that are not in phase are typically described by the angular difference between them, such as, "180 degrees out of phase." Zero-phase wavelets are symmetrical in shape about zero time whereas non-zero-phase wavelets are asymmetrical. Non-zero-phase wavelets are converted to zero-phase wavelets to achieve the best resolution of the seismic data. Known (zero) phase well synthetics and vertical seismic profiles (VSPs) can be compared with local surface seismic data to determine the relative phase of the surface seismic wavelets. Such knowledge allows the surface seismic data to be "corrected" to zero phase. The units of phase are degrees.
3035attribute, character, coherence, coherent noise, complex-trace analysis, footprint, hydrocarbon indicator, resolution, spectral, spectrum, synthetic seismogram, wavefront, wavelet, zero-phase
3036None
3037None
3038--
3039pore pressure gradient
30401.n. [Geology]
3041The change in pore pressure per unit of depth, typically in units of psi/ft or kPa/m. Pressure increases predictably with depth in areas of normal pressure. The normalhydrostatic pressuregradient for freshwater is 0.433 psi/ft, or 9.792 kPa/m, and 0.465 psi/ft for water with 100,000ppmtotaldissolved solids(a typical Gulf Coast water), or 10.516 kPa/m. Deviations from normal pressure are described as high or low pressure.
3042abnormal pressure, formation pressure, geopressure gradient, lithostatic pressure, normal pressure, pore pressure, pressure gradient
3043None
3044None
3045--
3046pore pressure gradient
30472.n. [Well Testing]
3048A change in pore pressure as a function of distance. This can refer to radial change in pore pressure with distance from the well (which can be calculated from well-test analysis results) or to change in pore pressure with depth (which can be measured by formation tests, and implies formation fluid density and/or fluid contacts).
3049formation fluid, pore pressure, pressure gradient
3050None
3051None
3052--
3053primary recovery
30541.n. [Production Testing, Enhanced Oil Recovery]
3055The first stage of hydrocarbon production, in which natural reservoir energy, such as gasdrive, waterdrive or gravity drainage, displaces hydrocarbons from the reservoir, into the wellbore and up to surface.Initially, the reservoir pressure is considerably higher than the bottomhole pressure inside the wellbore. This high natural differential pressure drives hydrocarbons toward the well and up to surface. However, as the reservoir pressure declines because of production, so does the differential pressure. To reduce the bottomhole pressure or increase the differential pressure to increase hydrocarbon production, it is necessary to implement an artificial lift system, such as a rod pump, an electrical submersible pump or a gas-lift installation. Production using artificial lift is considered primary recovery.The primary recovery stage reaches its limit either when the reservoir pressure is so low that the production rates are not economical, or when the proportions of gas or water in the production stream are too high. During primary recovery, only a small percentage of the initial hydrocarbons in place are produced, typically around 10% for oil reservoirs.Primary recovery is also called primary production.
3056artificial lift, enhanced oil recovery, gas-cap drive, gravity drainage, reservoir pressure, reservoir-drive mechanisms, secondary recovery, solution gasdrive, tertiary recovery
3057primary production
3058None
3059--
3060paddle blender
30611.n. [Drilling Fluids, Well Workover and Intervention]
3062A type of fluid-mixing tank used in the preparation of treatment fluids or slurries that provides the agitation to achieve a well-dispersed mixture. Paddle mixers are generally equipped with rotating paddles that provide turbulence for mixing fluids and an action that prevents the settling of solids prior to being pumped.
3063None
3064None
3065None
3066--
3067phase redistribution
30681.n. [Well Testing]
3069A pressure phenomenon caused in a wellbore by rise of gas and fall of liquids trapped in a wellbore after a surface shut-in. This phenomenon can cause a "hump" in the buildup curve, and frequently leads to incorrect analysis of buildup test results because the entire early portion of the transient is adversely affected by this pressure response.
3070humping
3071None
3072None
3073--
3074pore throat
30751.n. [Formation Evaluation]
3076In an intergranular rock, the small pore space at the point where two grains meet, which connects two larger pore volumes. The number, size and distribution of the pore throats control many of the resistivity, flow and capillary-pressure characteristics of the rock.
3077effective porosity, microporosity, small-pore water, total porosity
3078None
3079None
3080--
3081prime mover
30821.n. [Drilling]
3083The source of power for the rig location. On modern rigs, the prime mover consists of one to four or more diesel engines. These engines commonly produce several thousand horsepower. Typically, the diesel engines are connected to electric generators. The electrical power is then distributed by a silicon-controlled-rectifier (SCR) system around the rigsite. Rigs that convert diesel power to electricity are known as diesel electric rigs. Older designs transmit power from the diesel engines to certain rig components (drawworks, pumps and rotary table) through a system of mechanical belts, chains and clutches. On these rigs, a smaller electric generator powers lighting and small electrical requirements. These older rigs are referred to as mechanical rigs or more commonly, simply power rigs.
3084drawworks, rotary table
3085None
3086None
3087--
3088paddle mixer
30891.n. [Drilling Fluids, Well Workover and Intervention]
3090A type of fluid-mixing tank used in the preparation of treatment fluids or slurries that provides the agitation to achieve a well-dispersed mixture. Paddle mixers are generally equipped with rotating paddles that provide turbulence for mixing fluids and an action that prevents the settling of solids prior to being pumped.
3091None
3092None
3093None
3094--
3095phase shift resistivity
30961.n. [Formation Evaluation]
3097The ability of the formation to resist electrical conduction, as derived from the change in position of the peaks of an electromagnetic wave generated in a <a href="Display.cfm?Term=propagation%20resistivity%20measurement">propagation <a href="Display.cfm?Term=resistivity">resistivity measurement. At the frequencies used, the phase shift depends mainly on the resistivity of the material with a small dependence on dielectric permittivity, particularly at high resistivity. Common practice is to transform the phase shift to resistivity assuming that the dielectric permittivity is related to resistivity by a simple algorithm. The transform also depends on transmitter/receiver spacings and tool design. For a 2-MHz measurement, a typical measurement range is 0.2 to 200 ohm-m. Above 200 ohm-m, the dielectric effects become too variable and it is preferable to use the dielectric resistivity.
3098attenuation resistivity, dielectric resistivity, phase shift, polarization horn, propagation resistivity
3099None
3100None
3101--
3102pore pressure gradient
31031.n. [Geology]
3104The change in pore pressure per unit of depth, typically in units of psi/ft or kPa/m. Pressure increases predictably with depth in areas of normal pressure. The normalhydrostatic pressuregradient for freshwater is 0.433 psi/ft, or 9.792 kPa/m, and 0.465 psi/ft for water with 100,000ppmtotaldissolved solids(a typical Gulf Coast water), or 10.516 kPa/m. Deviations from normal pressure are described as high or low pressure.
3105abnormal pressure, formation pressure, geopressure gradient, lithostatic pressure, normal pressure, pore pressure, pressure gradient
3106None
3107None
3108--
3109pore pressure gradient
31102.n. [Well Testing]
3111A change in pore pressure as a function of distance. This can refer to radial change in pore pressure with distance from the well (which can be calculated from well-test analysis results) or to change in pore pressure with depth (which can be measured by formation tests, and implies formation fluid density and/or fluid contacts).
3112formation fluid, pore pressure, pressure gradient
3113None
3114None
3115--
3116processing
31171.n. [Geophysics]
3118Alteration of seismic data to suppress noise, enhance signal and migrate seismic events to the appropriate location in space. Processing steps typically include analysis of velocities and frequencies, static corrections, deconvolution, normal moveout, dip moveout, stacking, and migration, which can be performed before or after stacking. Seismic processing facilitates better interpretation because subsurface structures and reflection geometries are more apparent.
3119acquisition, amplitude anomaly, amplitude variation with offset, automatic gain control, bias, brute stack, common depth point, common midpoint, common midpoint method, convolution, depth conversion, depth migration, dip moveout, dynamic correction, embedded wavelet, event, filter, frequency, header, interpretation, inversion, lag, migration, normal moveout, peg-leg multiple, quicklook, random noise, resolution, short-path multiple, signature deconvolution, sinc x, slant stack, space-frequency domain, stack, static correction, three-dimensional survey, time migration, true-amplitude recovery, velocity, wavelet extraction, work station, zero-phase
3120seismic processing
3121None
3122--
3123paleontology
31241.n. [Geology]
3125The study of fossilized, or preserved, remnants of plant and animal life. Changes in the Earth through time can be documented by observing changes in the fossils in successive strata and the environments in which they formed or were preserved. Fossils can also be compared with their extant relatives to assess evolutionary changes. Correlations of strata can be aided by studying their fossil content, a discipline called biostratigraphy.
3126biostratigraphy, correlation, depositional environment, fossil, geochronology, geologic time scale, micropaleontology, palynology, relative age, stratigraphy, stratum
3127None
3128None
3129--
3130phase velocity log
31311.n. [Production Logging]
3132A record of the velocity with which a particular phase (gas, oil or water) moves in a producing well. While most flowmeters measure some average of all the fluids, the phase-velocity log identifies one particular phase. This is particularly important in highly deviated and horizontal wells with multiphase flow, where the flow structure is complicated.Phase-velocity measurements are made with either the crosscorrelation flowmeter, the water-flow log, or with chemical markers designed to mix specifically with one particular phase. Velocity-shot measurements, using radioactive tracers, have also been used. In a typical chemical marker technique, a gadolinium-rich marker is injected into the flow stream, dissolving in either oil or water. Gadolinium has a high capture cross section, or sigma, so that a slug of fluid with high sigma moves with the appropriate phase up the borehole. This slug can be detected by a standard pulsed-neutron capture tool, and the velocity of the phase computed from the time of flight between ejector and detector.
3133crosscorrelation flowmeter, flowmeter, holdup log, multiphase flow, production log, tracer measurement, water-flow log
3134None
3135None
3136--
3137porosimeter
31381.n. [Formation Evaluation]
3139An instrument for measuring the pore volume, and hence the porosity, of a core sample. The term is also used for some instruments that actually measure grain volume, such as the Boyle?s Law Double-Cell method. Pore volume is then obtained from the difference between bulk volume and grain volume.Pore volume is most commonly measured directly by Boyle's Law Single-Cell method, summation of fluids or liquid saturation. Bulk volume is most commonly measured by buoyancy, mercury displacement or a physical measurement of size (calipering); grain volume by Boyle?s law Double-Cell method or disaggregation of the sample.Except for disaggregation, all techniques determine the effective porosity, in the sense of all but the isolated pores.
3140core plug, effective porosity, routine core analysis, whole core
3141None
3142None
3143--
3144produced water
31451.n. [Shale Gas]
3146A term used to describe water produced from a wellbore that is not a treatment fluid. The characteristics of produced water vary and use of the term often implies an inexact or unknown composition. It is generally accepted that water within the pores of shale reservoirs is not produced due to its low relative permeability and its mobility being lower than that of gas.
3147None
3148None
3149None
3150--
3151palynology
31521.n. [Geology]
3153The study of fossilized remnants of microscopic entities having organic walls, such as pollen, spores and cysts from algae. Changes in the Earth through time can be documented by studying the distribution of spores and pollen. Well log and other correlations are enhanced by incorporating palynology. Palynology also has utility in forensics.
3154biostratigraphy, fossil, micropaleontology, paleontology
3155None
3156None
3157--
3158phase shift resistivity
31591.n. [Formation Evaluation]
3160The ability of the formation to resist electrical conduction, as derived from the change in position of the peaks of an electromagnetic wave generated in a <a href="Display.cfm?Term=propagation%20resistivity%20measurement">propagation <a href="Display.cfm?Term=resistivity">resistivity measurement. At the frequencies used, the phase shift depends mainly on the resistivity of the material with a small dependence on dielectric permittivity, particularly at high resistivity. Common practice is to transform the phase shift to resistivity assuming that the dielectric permittivity is related to resistivity by a simple algorithm. The transform also depends on transmitter/receiver spacings and tool design. For a 2-MHz measurement, a typical measurement range is 0.2 to 200 ohm-m. Above 200 ohm-m, the dielectric effects become too variable and it is preferable to use the dielectric resistivity.
3161attenuation resistivity, dielectric resistivity, phase shift, polarization horn, propagation resistivity
3162None
3163None
3164--
3165porosity
31661.n. [Geology]
3167The percentage of pore volume or void space, or that volume within rock that can contain fluids. Porosity can be a relic of deposition (primary porosity, such as space between grains that were not compacted together completely) or can develop through alteration of the rock (secondary porosity, such as when feldspar grains or fossils are preferentially dissolved from sandstones). Porosity can be generated by the development of fractures, in which case it is called fracture porosity. Effective porosity is the interconnected pore volume in a rock that contributes to fluid flow in a reservoir. It excludes isolated pores. Total porosity is the total void space in the rock whether or not it contributes to fluid flow. Thus, effective porosity is typically less than total porosity. Shale gas reservoirs tend to have relatively high porosity, but the alignment of platy grains such as clays makes their permeability very low.
3168carbonate, compaction correction, consolidated, cubic packing, diagenesis, diagenetic porosity, differential compaction, dolomite, dolomitization, effective porosity, evaporite, feldspar, fracture porosity, horizon, impermeable, moldic porosity, pay, permeability, petrography, pore, primary porosity, reef, reservoir, rhombohedral packing, sandstone, saturation, secondary porosity, sorting, vesicular porosity, vugular porosity
3169None
3170None
3171--
3172producing formation
31731.n. [Well Testing]
3174An underground rock formation from which oil, gas or water is produced. Any porous rock will contain fluids of some sort, and all rocks at considerable distance below the Earth's surface will initially be under pressure, often related to the hydrostatic column of ground waters above the reservoir. To produce, rocks must also have permeability, or the capacity to permit fluids to flow through them.
3175None
3176None
3177None
3178--
3179pao
31801.n. [Drilling Fluids]
3181One of the synthetic hydrocarbon liquids manufactured from the monomer ethylene, H2C=CH2. Polyalphaolefins have a complex branched structure with an olefin bond in the alpha position of one of the branches. Hydrogenated polyalphaolefins have olefin-carbons saturated with hydrogen, which lends excellent thermal stability to the molecule. Synthetic-base fluids (similar to oil muds) are made with the various types of synthetic liquids because the cuttings can be discharged in offshore waters, whereas discharge of cuttings coated with refined oils would be disallowed.
3182diesel-oil mud
3183None
3184polyalphaolefin
3185--
3186phase velocity log
31871.n. [Production Logging]
3188A record of the velocity with which a particular phase (gas, oil or water) moves in a producing well. While most flowmeters measure some average of all the fluids, the phase-velocity log identifies one particular phase. This is particularly important in highly deviated and horizontal wells with multiphase flow, where the flow structure is complicated.Phase-velocity measurements are made with either the crosscorrelation flowmeter, the water-flow log, or with chemical markers designed to mix specifically with one particular phase. Velocity-shot measurements, using radioactive tracers, have also been used. In a typical chemical marker technique, a gadolinium-rich marker is injected into the flow stream, dissolving in either oil or water. Gadolinium has a high capture cross section, or sigma, so that a slug of fluid with high sigma moves with the appropriate phase up the borehole. This slug can be detected by a standard pulsed-neutron capture tool, and the velocity of the phase computed from the time of flight between ejector and detector.
3189crosscorrelation flowmeter, flowmeter, holdup log, multiphase flow, production log, tracer measurement, water-flow log
3190None
3191None
3192--
3193porosity exponent
31941.n. [Formation Evaluation]
3195The exponent, m, in the relation of formation factor (F) to porosity (phi). For a single sample, F is related to phi using the Archie equation F = 1 / phim, with m being the only coefficient needed. In this case, m has been related to many physical parameters, but above all to the tortuosity of the pore space. In theory, it can range from 1 for a bundle of tubes to infinity for porosity that is completely unconnected. For a simple packing of equal spheres, m = 1.5. With a more tortuous pore space or more isolated pores, m increases, while with fractures or conductive solids, m decreases. As a general average for typical reservoir rocks, m is often taken as 2.For a group of rock samples, it is common practice to find a relationship between F and phi that uses two coefficients (F = a / phim). In this case m, like a, becomes an empirical constant of best fit between F and phi, and may take a wide range of values. In complex formations, such as shaly sands or carbonates with multiple pore types, a constant m does not give good results. One solution is to vary m, with the variability related to parameters such as porosity, shaliness, or rock texture, or else determined directly from logs in zones where the water saturation is known or can be computed from a nonresistivity measurement such as electromagnetic propagation.In shaly sands, the preferred solution is to use a saturation equation, such as Waxman-Smits, dual water, SGS or CRMM, in which m is defined as the intrinsic m, determined from the intrinsic formation factor at high salinities or after correction for the effect of shale. In carbonates with multiple pore types, such as fractures, vugs, interparticle porosity and microporosity, one solution is to use equations with different porosity exponents for each pore type. The volume of each pore type must then be determined from logs or borehole images.
3196Archie equation, dual water
3197None
3198None
3199--
3200production casing
32011.n. [Well Completions]
3202A casing string that is set across the reservoir interval and within which the primary completion components are installed.
3203casing string, primary completion components
3204None
3205None
3206--
3207paraffin
32081.n. [Well Completions]
3209A hydrocarbon compound that often precipitates on production components as a result of the changing temperatures and pressures within the production system. Heavy paraffins occur as wax-like substances that may build up on the completion components and may, if severe, restrict production.Paraffin is normally found in the tubing close to surface. Nevertheless, it can form at the perforations, or even inside the formation, especially in depleted reservoirs or reservoirs under gas-cycling conditions.
3210organic deposit, paraffin, paraffin inhibitor, paraffin scratcher, paraffinic hydrocarbon
3211None
3212None
3213--
3214photoelectric effect
32151.n. [Formation Evaluation]
3216A gamma ray interaction in which the gamma ray is fully absorbed by a bound electron. If the energy transferred exceeds the binding energy to the atom, the electron will be ejected. Normally, the ejected electron will be replaced within the material and a characteristic X-ray will be emitted with an energy that is dependent on the atomic number of the material. The highest probability for this effect occurs at low gamma ray energy and in a material of high atomic number. The photoelectric effect is the principle behind the PEF log, which identifies lithology.
3217Compton scattering, cross section
3218None
3219None
3220--
3221porous
32221.adj. [Geology]
3223Pertaining to rocks that incorporate pores or void spaces, which can contain air, water, hydrocarbons or other fluids. In a body of rock, the percentage of pore space is the porosity.Porosity can be a relic of deposition (primary porosity, such as space between grains that were not compacted together completely) or can develop through alteration of the rock (secondary porosity, such as when feldspar grains or fossils are preferentially dissolved from sandstones).Porosity can be generated by the development of fractures, in which case it is called fracture porosity. Effective porosity is the interconnected pore volume in a rock that contributes to fluid flow in a reservoir. It excludes isolated pores. Total porosity is the total void space in the rock whether or not it contributes to fluid flow. Thus, effective porosity is typically less than total porosity.Shale gas reservoirs tend to have relatively high porosity, but the alignment of platy grains such as clays makes their permeability very low.
3224carbonate, compaction correction, consolidated, cubic packing, diagenesis, diagenetic porosity, differential compaction, dolomite, dolomitization, effective porosity, evaporite, feldspar, fracture porosity, horizon, impermeable, moldic porosity, pay, permeability, petrography, pore, primary porosity, reef, reservoir, rhombohedral packing, sandstone, saturation, secondary porosity, sorting, vesicular porosity, vugular porosity
3225None
3226None
3227--
3228production log
32291.n. [Production Logging]
3230A record of one or more in-situ measurements that describe the nature and behavior of fluids in or around the borehole during production or injection. Production logs are run for the purpose of analyzing dynamic well performance and the productivity or injectivity of different zones, diagnosing problem wells, or monitoring the results of a stimulation or completion. The term is sometimes extended to include logs run to measure the physical condition of the well, for example cement bond and corrosion logs.The earliest production logs consisted of temperature logs (1930s) and flowmeters (1940s), to which were soon added fluid-density and capacitance logs (1950s). Flow-rate measurements were gradually improved by the development of tracer logs and improvement to the basic spinner flowmeter.These techniques were adequate for near-vertical wells with single or biphasic flow, but could be misleading in highly deviated, and especially horizontal, wells. New techniques were developed starting in the 1980s. These techniques focused on local probes to measure holdup at different points in the borehole, nuclear techniques to analyze the total holdup of all three phases, and phase-velocity logs for the analysis of individual fluids. At the same time, complex flow structures and flow regimes have been studied more extensively using flow loops.
3231cement bond log, differential-temperature log, distributed-temperature log, fluid-density log, gas-holdup log, holdup log, noise log, radial differential-temperature log, radioactive-tracer log, spinner flowmeter, water-flow log
3232None
3233None
3234--
3235paraffin inhibitor
32361.n. [Enhanced Oil Recovery]
3237A chemical injected into the wellbore to prevent or minimize paraffin deposition. The effectiveness of paraffin inhibitors is strongly dependent on crude oil composition.Paraffin inhibitors must be introduced into the oil before the oil cools to its cloud point. In additional, asphaltene composition should be determined before treatment because it can reduce the effectiveness of the paraffin inhibitor. In some cases, the use of a paraffin inhibitor can actually increase the rate of paraffin deposition because the stability of colloidal asphaltenes is disturbed.
3238organic deposit
3239None
3240None
3241--
3242photon log
32431.n. [Production Logging]
3244A record of the density in and around a completed well using a radioactive source of gamma rays and a detector. The log is recorded with a nuclear fluid densimeter. Originally, photon logs were run to determine the size of salt caverns. More recently, they have been run to evaluate the quality of gravel packs and sand cavities, and are then synonymous with gravel-pack logs.
3245gravel pack, nuclear fluid densimeter
3246gravel-pack log
3247None
3248--
3249portland cement
32501.n. [Drilling Fluids]
3251The product obtained by pulverizing clinker consisting essentially of hydraulic calcium silicates. Portland cement is the most common type of cement used for oil- and gas-well cementing.
3252None
3253None
3254None
3255--
3256production period
32571.n. [Well Testing]
3258The flow period before a buildup. The duration of the production period should be specified in the test design to assure that a stable flow situation is reached, and that the pressure disturbance has reached far enough into the formation to allow determination of a representative value for kh. For reservoir-limits testing, the production period must be long enough for the pressure disturbance to have reached the boundaries of interest.
3259None
3260None
3261None
3262--
3263paraffin scraper
32641.n. [Well Workover and Intervention]
3265A downhole tool, generally run on slickline, used to remove paraffin and soft wax deposits from the internal wall of production tubulars and completion equipment.
3266pig
3267None
3268None
3269--
3270phpa
32711.n. [Drilling Fluids]
3272A class of water muds that use partially-hydrolyzed polyacrylamide (PHPA) as a functional additive, either to control wellbore shales or to extend bentonite clay in a low-solids mud. As a shale-control mud, PHPA is believed to seal microfractures and coat shale surfaces with a film that retards dispersion and disintegration. KCl is used as a shale inhibitor in most PHPA mud designs. In low-solids muds, PHPA interacts with minimal concentrations of bentonite to link particles together and improve rheology without increased colloidal solids loading.Reference:Clark RK, Scheuerman RF, Raoth H and van Laar H: "Polyacrylamide-Potassium Chloride Mud for Drilling Water Sensitive Shales," Journal of Petroleum Technology 28, no. 6 (June 1976): 719-726.Reference:Fraser LJ: "New Method Accurately Analyzes PHPA's in Muds," Oil &amp; Gas Journal 85, no. 27 (July 6, 1987): 39-42.
3273acrylamide-acrylate polymer, PHPA mud, polymer, potassium mud, wastewater cleanup
3274None
3275None
3276--
3277portland cement clinker
32781.n. [Drilling Fluids]
3279Hard granular nodules composed essentially of hydraulic calcium silicates, with smaller quantities of calcium aluminates and ferrites. Portland cement clinker is produced by the heat treatment of cement raw materials in a kiln. Clinker is pulverized with gypsum in the manufacture of portland cement.
3280None
3281None
3282None
3283--
3284production string
32851.n. [Well Completions]
3286The primary conduit through which reservoir fluids are produced to surface. The production string is typically assembled with tubing and completion components in a configuration that suits the wellbore conditions and the production method. An important function of the production string is to protect the primary wellbore tubulars, including the casing and liner, from corrosion or erosion by the reservoir fluid.
3287production tubing
3288None
3289None
3290--
3291paraffin scratcher
32921.n. [Well Workover and Intervention]
3293A downhole tool, generally run on slickline, used to remove paraffin and soft wax deposits from the internal wall of production tubulars and completion equipment.
3294pig
3295None
3296None
3297--
3298phpa mud
32991.n. [Drilling Fluids]
3300A class of water muds that use partially-hydrolyzed polyacrylamide (PHPA) as a functional additive, either to control wellbore shales or to extend bentonite clay in a low-solids mud. As a shale-control mud, PHPA is believed to seal microfractures and coat shale surfaces with a film that retards dispersion and disintegration. KCl is used as a shale inhibitor in most PHPA mud designs. In low-solids muds, PHPA interacts with minimal concentrations of bentonite to link particles together and improve rheology without increased colloidal solids loading.Reference:Clark RK, Scheuerman RF, Raoth H and van Laar H: "Polyacrylamide-Potassium Chloride Mud for Drilling Water Sensitive Shales," Journal of Petroleum Technology 28, no. 6 (June 1976): 719-726.Reference:Fraser LJ: "New Method Accurately Analyzes PHPA's in Muds," Oil &amp; Gas Journal 85, no. 27 (July 6, 1987): 39-42.
3301acrylamide polymer, acrylamide-acrylate polymer, acrylate polymer, beneficiation, clay extender, clay-water interaction, clear-water drilling, encapsulation, flocculant, hardness ion, low-solids mud, potassium mud, seawater mud
3302None
3303PHPA
3304--
3305positive displacement pump
33061.n. [Drilling, Well Workover and Intervention, Well Completions]
3307A type of fluid pump in which the displacement volume of the pump is fixed for each rotation of the pump. Generally associated with high-pressure applications, positive-displacement pumps are commonly used in drilling operations to circulate the drilling fluid and in a range of oil and gas well treatments, such as cementing, matrix treatments and hydraulic fracturing.
3308None
3309None
3310None
3311--
3312production tree
33131.n. [Production]
3314A Christmas tree that is installed once fracturing has been completed and the frac tree has been removed. Production trees tend to have smaller bores and lower pressure ratings than those of frac trees, which makes them more economical to use during the less-demanding production phase.
3315None
3316None
3317None
3318--
3319paraffinic hydrocarbon
33201.n. [Drilling Fluids]
3321The group of hydrocarbons consisting of linear molecules with the formula CnH2n+2. Methane, CH4, is the simplest member. Higher members, starting at about C18, are wax-like and are called paraffin. Excessive amounts of paraffinic hydrocarbons in an oil mud adversely affect mud flow and oil removal from cuttings at cool temperatures.
3322aliphatic compound, aromatic hydrocarbon, naphthenic hydrocarbon, olefinic hydrocarbon, pour point
3323None
3324None
3325--
3326pickett plot
33271.n. [Formation Evaluation]
3328A double logarithmic plot of a resistivity measurement on the x-axis versus a porosity measurement on the y-axis. The plot is named after G.R. Pickett. The plot is based on taking the logarithm of the Archie equation. Points of constant water saturation (Sw) will plot on a straight line with negative slope of value m. Water zones define the lowermost line on the plot. Since Sw = 1, the water resistivity can be determined from a point on the line. Once the water line is established, other parallel lines can be drawn for different Sw, assuming a constant n (usually 2). Other data can then be plotted and interpreted in terms of Sw. The same technique can be applied to the flushed zone, using flushed-zone measurements.See Pickett GR: "A Review of Current Techniques for Determination of Water Saturation from Logs," paper SPE 1446, presented at the SPE Rocky Mountain Regional Meeting, Denver, Colorado, USA, May 23-24, 1966; SPE Journal of Petroleum Technology (November 1966): 1425-1435.
3329Archie equation, flushed zone, water saturation
3330None
3331None
3332--
3333positive displacement pump
33341.n. [Drilling, Well Completions]
3335A type of fluid pump in which the displacement volume of the pump is fixed for each rotation of the pump. Generally associated with high-pressure applications, positive-displacement pumps are commonly used in drilling operations to circulate the drilling fluid and in a range of oil and gas well treatments, such as cementing, matrix treatments and hydraulic fracturing.
3336None
3337None
3338None
3339--
3340production wing
33411.n. [Well Completions]
3342The portion of a Christmas tree or surface production facility through which production fluids flow. The production wing typically includes a wing valve and a choke to control or isolate flow from the wellbore.
3343Christmas tree
3344None
3345None
3346--
3347parallel resistivity
33481.n. [Formation Evaluation]
3349The resistivity of a formation measured by flowing current parallel to the bedding planes. In anisotropic formations, the parallel and perpendicular resistivities are different.
3350electrical anisotropy, horizontal resistivity, vertical resistivity
3351None
3352None
3353--
3354pig
33551.n. [Production Testing]
3356A device with blades or brushes inserted in a pipeline for cleaning purposes. The pressure of the oil stream behind pushes the pig along the pipeline to clean out rust, wax, scale and debris. These devices are also called scrapers.
3357pig run
3358scraper
3359None
3360--
3361pig
33622.n. [Production Testing]
3363A spheroid implement used to displace liquid hydrocarbons from natural gas pipelines. They are also called signaling and batching pigs.
3364None
3365None
3366None
3367--
3368pig
33693.vb. [Production Testing]
3370To run a scraper, or pig, through a pipeline for cleaning purposes.
3371None
3372scraper
3373None
3374--
3375post mature
33761.adj. [Geology]
3377Pertaining to a hydrocarbon source rock that has generated as much hydrocarbon as possible and is becoming thermally altered.
3378diagenesis, generation, hydrocarbon, maturity, metamorphism, source rock
3379overmature
3380Antonyms:immature
3381--
3382productivity index pi
33831.n. [Well Completions]
3384A mathematical means of expressing the ability of a reservoir to deliver fluids to the wellbore. The PI is usually stated as the volume delivered per psi of drawdown at the sandface (bbl/d/psi).
3385None
3386None
3387PI
3388--
3389parasequence
33901.n. [Geology]
3391Relatively conformable depositional units bounded by surfaces of marine flooding, surfaces that separate older strata from younger and show an increase in water depth in successively younger strata. Parasequences are usually too thin to discern on seismic data, but when added together, they form sets called parasequence sets that are visible on seismic data.
3392depositional environment, flooding surface, sequence stratigraphy, stratum
3393None
3394None
3395--
3396pigging
33971.vb. [Production Testing]
3398The act of forcing a device called a pig through a pipeline for the purposes of displacing or separating fluids, and cleaning or inspecting the line.
3399pig run
3400None
3401None
3402--
3403post mature
34041.adj. [Geology]
3405Pertaining to a hydrocarbon source rock that has generated as much hydrocarbon as possible and is becoming thermally altered.
3406diagenesis, generation, hydrocarbon, maturity, metamorphism, source rock
3407overmature
3408Antonyms:immature
3409--
3410profit oil
34111.n. [Oil and Gas Business]
3412The amount of production, after deducting cost oil production allocated to costs and expenses, that will be divided between the participating parties and the host government under the production sharing contract.
3413cost oil, production sharing contract
3414None
3415None
3416--
3417parasequence set
34181.n. [Reservoir Characterization]
3419A succession of genetically related parasequences that form a distinctive stacking pattern, and that are typically bounded by major marine flooding surfaces and their correlative surfaces. Parasequence sets are usually classified as progradational, aggradational or retrogradational.
3420parasequence boundary, sequence stratigraphy
3421None
3422None
3423--
3424pill
34251.n. [Drilling]
3426Any relatively small quantity (less than 200 bbl) of a special blend of drilling fluid to accomplish a specific task that the regular drilling fluid cannot perform. Examples include high-viscosity pills to help lift cuttings out of a vertical wellbore, freshwater pills to dissolve encroaching salt formations, pipe-freeing pills to destroy filter cake and relieve differential sticking forces and lost circulation material pills to plug a thief zone.
3427cuttings, differential sticking, drilling fluid, lost circulation material, thief zone
3428None
3429None
3430--
3431pill
34322.n. [Drilling Fluids]
3433A small volume of mud used for a specific purpose in a drilling operation. Various types of pills are needed from time to time on the rig, such as to stop circulation loss or free stuck drillpipe.
3434granular lost-circulation material, gunk plug, lost circulation, lost-circulation material, mud, rheology, slug, spotting fluid, viscosity
3435None
3436None
3437--
3438pill
34393.n. [Well Workover and Intervention]
3440A relatively small volume of specially prepared fluid placed or circulated in the wellbore. Fluid pills are commonly prepared for a variety of special functions, such as a sweep pill prepared at high viscosity to circulate around the wellbore and pick up debris or wellbore fill. In counteracting lost-circulation problems, a lost-circulation pill prepared with flaked or fibrous material is designed to plug the perforations or formation interval losing the fluid.
3441None
3442None
3443None
3444--
3445potassium
34461.n. [Formation Evaluation]
3447An element with an atomic number of 19. The 40K isotope is radioactive, decaying with the emission of a single gamma ray of 1.46 MeV with a half-life of 1.3 * 109 years to give a stable isotope of argon. Potassium is the largest source of natural radioactivity. It occurs in illite, alkali feldspars, micas and some evaporite minerals. It also occurs in some drilling mud systems. The 40K isotope is only a small fraction, about 0.012%, of the total potassium, the main isotope being 39K, which has an abundance of about 1.7% in the Earth's crust. For the purposes of logging, the total potassium is calculated from the measured quantity of 40K and scaled in percent by weight. It is a valuable aid in determining the mineral content of a formation.
3448gamma ray log, natural gamma ray spectroscopy, thorium, uranium
3449None
3450None
3451--
3452progradation
34531.n. [Geology]
3454The accumulation of sequences by deposition in which beds are deposited successively basinward because sediment supply exceeds accommodation. Thus, the position of the shoreline migrates into the basin during episodes of progradation, a process called regression.
3455accommodation, bed, regression, sequence stratigraphy
3456None
3457Antonyms:retrogradation
3458--
3459parcom
34601.n. [Drilling Fluids]
3461The Oslo and Paris Commission, formerly known as PARCOM. The commission is a group of experts who advise North Sea countries on environmental policy and legislation. OSPAR has been influential in establishing North Sea legislation on drilling fluids that has served as the model for other operating areas. OSPAR has published lists of environmentally acceptable and unacceptable products, referred to as the "green," "grey" and "black" lists. The Green or A list consists of products posing relatively little harm to the environment (specifically the marine environment). Examples include inert minerals such as bentonite, inorganic salts that are common constituents of seawater such as sodium and potassium chloride, and simple organic products such as starch and carboxymethylcellulose (CMC). The Grey List consists of products 'requiring strong regulatory control' and includes heavy metals such as zinc, lead and chromium. The Black list covers products considered unsuitable for discharge and includes mercury, cadmium and 'persistent oils and hydrocarbons of a petroleum origin.' The inclusion of hydrocarbons in the black list has been the driving force behind the reduction of oil discharges in the North Sea and elsewhere and has serious implications for the use of oil and synthetic fluids.
3462None
3463black list, gray list, green list, grey list
3464OSPAR
3465--
3466pilot mill
34671.n. [Well Workover and Intervention]
3468A downhole milling tool designed with an extended pilot or central stinger section that is inserted in the bore of the packer, tubular or equipment being milled. This design helps ensure that the mill follows the desired path and does not damage the casing or liner wall as the milling operation progresses.
3469None
3470None
3471None
3472--
3473potassium ion
34741.n. [Drilling Fluids]
3475The ion of potassium, K+. There are tests used to monitor high (&gt;5000 mg/L) or low (&lt;5000 mg/L) potassium ion (K+) concentration in water-base muds. The test for highconcentration, as specified by the API, is based on the insolubility of potassium perchlorate. A volume of mud filtrate is mixed with an excess of NaClO4 in a centrifuge tube. White KClO4 is precipitated by the reaction. After thetube has spun in a centrifuge to settle the white sediment in the tube, the amount of precipitate is read and compared to a calibration chart that relates sediment to concentration of K+ in the filtrate sample. The test to monitor lowpotassium ion (K+) concentration in water-base muds, as prescribed by API, is a titration procedure using quaternary ammonium salt solution (QAS) as reagent. Potassium ion is first precipitated as the tetraphenylborate (TPB) salt by adding anexcess of sodium tetraphenylborate. After filtering out the solid, the amount of TPB not reacted with K+ ion is titrated with a standard QAS solution. The endpoint is purple-to-light blue color change.
3476None
3477None
3478None
3479--
3480progressive cavity pumping system
34811.n. [Production Testing]
3482A type of a sucker rod-pumping unit that uses a rotor and a stator. The rotation of the rods by means of an electric motor at surface causes the fluid contained in a cavity to flow upward. It is also called a rotary positive-displacement unit.
3483rod pump
3484None
3485None
3486--
3487particle plugging apparatus
34881.n. [Drilling Fluids]
3489A specialized apparatus used in the particle-plugging test. The PPA is used to determine the ability of particles in the drilling fluid to effectively bridge the pores in the filter medium and, therefore, the ability of the mud to reduce formation damage in the reservoir. The apparatus resembles a high-pressure, high-temperature filtration cell that has been modified to operate upside down (to remove the effects of gravity) and to accept filter media of different permeabilities (sintered metal, which is chosen for higher temperature conditions, aloxite, which is a porous ceramic material, or rock). The medium is selected to match the permeability of the reservoir to be drilled. The filter medium is at the top so that sediment will not affect the filter cake. Pressure is applied hydraulically from below.
3490None
3491None
3492particle-plugging apparatus
3493--
3494pilot operated regulator
34951.n. [Production]
3496A regulator that is controlled by a second small-volume, high-accuracy regulator or pilot. This arrangement has the advantage of improving performance by reducing the effects of unbalanced pressure and droop.
3497None
3498None
3499None
3500--
3501potassium mud
35021.n. [Drilling Fluids]
3503A class of muds that contain potassium ion (K+) dissolved in the water phase. Potassium muds are the most widely accepted water mud system for drilling water-sensitive shales, especially hard, brittle shales. K+ ions attach to clay surfaces and lend stability to shale exposed to drilling fluids by the bit. The ions also help hold the cuttings together, minimizing dispersion into finer particles. The presence of Na+ ions counteracts the benefits of K+ ions and should be minimized by using fresh water (not sea water) for make-up water. With time, Na+, Ca+2 and other ions accumulate from ion exchange with clays, making the mud less effective, but regular treatment to remove Ca+2 improves polymer function. Potassium chloride, KCl, is the most widely used potassium source. Others are potassium acetate, potassium carbonate, potassium lignite, potassium hydroxide and potassium salt of PHPA. Use of bentonite clay is restricted because of its strong affinity for K+. Instead, various polymers are used. XC polymer and PHPA are used for rheology. For fluid-loss control, mixtures of starch and polyanionic cellulose are often used. CM starch, HP starch, carboxymethylcellulose and sodium polyacrylate (SPA) are also used. PHPA is widely used for shale encapsulation. Potassium, lime and starch-like polymers have also been used as potassium mud systems. Although three API methods exist for determining the K+ ion concentration, the centrifuge method (for K+ &gt;5000 mg/L) is the most accepted field method, and essential for daily monitoring of potassium in a mud. Regular additions of potassium salt maintain shale stability. K+ ion is rapidly consumed while drilling shallow, soft and highly dispersive (gumbo) shales, but maintaining sufficient K+ ion to stabilize gumbo can become expensive when drilling large holes. Researchers, notably Dr. Dennis O'Brien and Dr. Martin Chenevert (while at Exxon Production Research), evaluated different shales, their clay mineralogy and the concentration of K+ needed to stabilize them. Potassium muds above about 1 wt.% K+ ion usually fail the mysid shrimp (US EPA) bioassay test. Therefore, K-muds currently find low acceptance in offshore drilling in USA waters.Reference:O'Brien DE and Chenevert ME: "Stabilizing Sensitive Shales with Inhibited Potassium-Based Drilling Fluids," Journal of Petroleum Technology 25, no. 9 (September 1973): 1089-1100.
3504acrylamide-acrylate polymer, carboxymethyl starch, caustic potash, clay-water interaction, encapsulation, EPA, inhibit, inhibitive mud, lime mud, PHPA mud, polyanionic cellulose, potassium ion, SPA, starch, water-base drilling fluid
3505None
3506None
3507--
3508progressive gels
35091.n. [Drilling Fluids]
3510The situation in which 10-second and 10-minute gel strengths for a drilling mud have dissimilar values, with the 10-minute number being much higher than the 10-second number. This indicates that the gelation of the mud is rapidly gaining strength with time, which generally is an undesirable feature of a mud. The mud may require excessive pump pressures to break circulation. If gels appear to be too progressive, a 30-minute gel-strength measurement may be warranted as a third check of progress.
3511flat gels, gel strength, gelled-up mud, shear-strength measurement test, zero-zero gels
3512None
3513None
3514--
3515particle size distribution
35161.n. [Drilling Fluids]
3517The weight, or net volume, of solid particles that fall into each of the various size ranges, given as a percentage of the total solids of all sizes in the sample of interest. Particle size can be determined by sieve analysis, light scattering, passage through an electrically charged orifice, settling rate or other methods. Data are typically shown as a histogram chart with percentage-smaller-than on the y-axis and size ranges on the x-axis. Mud engineers use such data to operate solids-control equipment effectively. Particle-size distributions are used to evaluate bridging materials for drill-in and completion fluids. Barite and hematite samples are examined to ensure performance without excessive wear on equipment and as an API/ISO quality specification.
3518None
3519None
3520particle-size distribution
3521--
3522pin
35231.n. [Drilling]
3524A male threadform, especially in tubular goods and drillstring components.
3525back off, box, break out, casing, casing string
3526None
3527None
3528--
3529pin
35302.adj. [Drilling]
3531Relating to the male threadform, as in the "pin end of the pipe."
3532box, threadform
3533None
3534None
3535--
3536pounds per barrel
35371.n. [Drilling Fluids]
3538USoilfieldunit of concentration, usually abbreviated to lbm/bbl. One lbm/bbl is the equivalent of one pound of additive in 42 US gallons ofmud. The "m" is used to denote mass to avoid possible confusion with pounds force (denoted by "lbf"). Sometimes lbm/bbl is written as ppb, but must not be confused with parts per billion. In SI units, the conversion factor is one pound per barrel equals 2.85 kilograms per cubic meter. For example, 10 lbm/bbl = 28.5 kg/m3.
3539barrel equivalent
3540None
3541lb/bbl, lbm/bbl, ppb
3542--
3543propagation resistivity
35441.n. [Formation Evaluation]
3545A measurements-while-drilling log of formation resistivity. The log normally contains at least one attenuation and one phase-shift resistivity reading. In many cases there will be multiple curves of both, the difference being the depth of investigation. For the same nominal depth of investigation, the attenuation resistivity reads deeper than the phase-shift resistivity and is less affected by invasion, but more affected by surrounding beds and apparent dip. The attenuation measurement has a poorer vertical resolution and is less affected by anisotropy. Depths of investigation and vertical resolution of both measurements vary with the average formation resistivity.Although depths of investigation are less than with wireline resistivity logs, the invasion at the time of measurement is usually small and it is possible to derive the resistivity of the undisturbed zone.
3546attenuation resistivity, depth of investigation, dielectric resistivity, electromagnetic propagation, horizontal resistivity, phase-shift resistivity, propagation resistivity measurement, resistivity log, undisturbed zone, vertical resistivity, vertical resolution
3547None
3548None
3549--
3550particle plugging apparatus
35511.n. [Drilling Fluids]
3552A specialized apparatus used in the particle-plugging test. The PPA is used to determine the ability of particles in the drilling fluid to effectively bridge the pores in the filter medium and, therefore, the ability of the mud to reduce formation damage in the reservoir. The apparatus resembles a high-pressure, high-temperature filtration cell that has been modified to operate upside down (to remove the effects of gravity) and to accept filter media of different permeabilities (sintered metal, which is chosen for higher temperature conditions, aloxite, which is a porous ceramic material, or rock). The medium is selected to match the permeability of the reservoir to be drilled. The filter medium is at the top so that sediment will not affect the filter cake. Pressure is applied hydraulically from below.
3553high-pressure, high-temperature filtration test, sintered
3554None
3555PPA
3556--
3557pipe dope
35581.n. [Drilling]
3559A specially formulated blend of lubricating grease and fine metallic particles that prevents thread galling (a particular form of metal-to-metal damage) and seals the roots of threads. The American Petroleum Institute (API) specifies properties of pipe dope, including its coefficient of friction. The rig crew applies copious amounts of pipe dope to the drillpipe tool joints every time a connection is made.
3560connection, dope, tool joint
3561None
3562None
3563--
3564pour point
35651.n. [Drilling Fluids]
3566The lowest temperature (in °F or °C) at which a liquid remains pourable (meaning it still behaves as a fluid). Oil or synthetic muds with high pour points may suffer from poor screening and excessive pressure, surges in deepwater wells or other operations subject to low temperatures. In oils, the pour point is generally increased by a high paraffin content. The pour point of liquid additives is an important consideration for arctic drilling operations.
3567cuttings, diesel-oil mud, oil mud, paraffinic hydrocarbon
3568None
3569None
3570--
3571pour point
35722.n. [Heavy Oil]
3573The temperature at which a fluid ceases to pour. The pour point for oil can be determined under protocols set forth in the ASTM D-97 pour point test, in which the pour point is established as that temperature at which oil ceases to flow when the sample is held at 90 degrees to the upright for five seconds. High pour points usually occur in crude oils that have significant paraffin content. Paraffins (or waxes) will start to precipitate as temperature decreases. At some point the precipitates accumulate to the point where the fluid can no longer flow. This phenomenon can occur with light oils as well as heavy oils.
3574None
3575None
3576None
3577--
3578propagation time
35791.n. [Formation Evaluation]
3580A measurement of the high frequency (about 1 GHz) dielectric properties of the formation. In a typical tool, a microwave transmitter is placed a few inches below two receivers separated by 4 cm [1.6 in.]. At this frequency, the response is best explained as the propagation of a wave. Thus the phase shift and attenuation of the wave between the receivers are measured and transformed to give the log measurements of propagation time and attenuation. Because of the short spacings, the measurement has excellent vertical resolution and reads within inches of the borehole wall except at high resistivity. Different transmitter and receiver spacings and orientations are used, leading to different arrays, such as the endfire array and the broadside array.An ideal measurement would give the plane wave properties of the formation. However, the geometry of the measurement precludes this, so that a correction, known as the spreading-loss correction, is needed for the attenuation and to a much smaller extent for the propagation time. The measurement is also affected by the dielectric properties and thickness of the mudcake. Borehole compensation is used to correct for sonde tilt or a rough borehole wall.
3581conductivity, electromagnetic propagation, filter cake, relative dielectric permittivity, spreading loss
3582electromagnetic propagation measurement
3583None
3584--
3585particle size distribution
35861.n. [Drilling Fluids]
3587The weight, or net volume, of solid particles that fall into each of the various size ranges, given as a percentage of the total solids of all sizes in the sample of interest. Particle size can be determined by sieve analysis, light scattering, passage through an electrically charged orifice, settling rate or other methods. Data are typically shown as a histogram chart with percentage-smaller-than on the y-axis and size ranges on the x-axis. Mud engineers use such data to operate solids-control equipment effectively. Particle-size distributions are used to evaluate bridging materials for drill-in and completion fluids. Barite and hematite samples are examined to ensure performance without excessive wear on equipment and as an API/ISO quality specification.
3588abrasion test, bridging material, mud engineer, sized calcium carbonate, sized salt
3589None
3590None
3591--
3592pipe rack
35931.n. [Drilling]
3594Onshore, two elevated truss-like structures having triangular cross sections. The pipe rack supports drillpipe, drill collars or casing above the ground. These structures are used in pairs located about 20 ft [6 m] apart and keep the pipe above ground level and closer to the level of the catwalk. Pipe stored horizontally on the pipe racks can have its threads cleaned and inspected and the rig crew may roll the pipe from one end of the pipe racks to the other with relative ease. The pipe racks are usually topped with a wooden board so as to not damage pipe, especially casing, as it is rolled back and forth along the racks. When large amounts of pipe are stored, wooden sills are placed between the layers of pipe to prevent damage.
3595catwalk, measured depth
3596None
3597None
3598--
3599pipe rack
36002.n. [Drilling]
3601Offshore, the storage bins for drillpipe, drill collars and casing. The offshore pipe rack functions similarly to the onshore version. Due to space limitations, offshore pipe racks tend to be narrower and routinely contain many layers of pipe. The onshore pipe rack tends to have few stacked layers and instead extends laterally as needed to hold the tubular goods because space is not at a premium.
3602None
3603None
3604None
3605--
3606power law fluid
36071.n. [Drilling Fluids]
3608A fluid described by the two-parameter rheological model of a pseudoplastic fluid, or a fluid whose viscosity decreases as shear rate increases. Water-base polymer muds, especially those made with XC polymer, fit the power-law mathematical equation better than the Bingham plastic or any other two-parameter model. Power-law fluids can be described mathematically as follows: 
3609Bingham plastic model, centipoise, direct-indicating viscometer, Herschel-Bulkley fluid, Newtonian fluid, non-Newtonian fluid, plastic fluid, pseudoplastic, rheological property, rheology, shear rate, shear stress, viscosity, XC polymer
3610None
3611None
3612--
3613proppant
36141.n. [Well Workover and Intervention, Shale Gas]
3615Sized particles mixed with fracturing fluid to hold fractures open after a hydraulic fracturing treatment. In addition to naturally occurring sand grains, man-made or specially engineered proppants, such as resin-coated sand or high-strength ceramic materials like sintered bauxite, may also be used. Proppant materials are carefully sorted for size and sphericity to provide an efficient conduit for production of fluid from the reservoir to the wellbore.
3616None
3617None
3618None
3619--
3620partitioning
36211.n. [Enhanced Oil Recovery]
3622The degree of solubilization of a solute into each of multiple immiscible phases at equilibrium. For example, a water-soluble surfactant injected as part of an enhanced oil recovery flood will partially solubilize, or partition, in the oil phase. The degree of partitioning will influence the efficiency of the enhanced oil recovery agent.
3623None
3624None
3625None
3626--
3627pipe ram
36281.n. [Drilling]
3629A type of sealing element in high-pressure split seal blowout preventers that is manufactured with a half-circle hole on the edge (to mate with another horizontally opposed pipe ram) sized to fit around drillpipe. Most pipe rams fit only one size or a small range of drillpipe sizes and do not close properly around drillpipe tool joints or drill collars. A relatively new style is the variable bore ram, which is designed and manufactured to properly seal on a wider range of pipe sizes.
3630blind ram, blowout preventer
3631None
3632None
3633--
3634power law fluid
36351.n. [Drilling Fluids]
3636A fluid described by the two-parameter rheological model of a pseudoplastic fluid, or a fluid whose viscosity decreases as shear rate increases. Water-base polymer muds, especially those made with XC polymer, fit the power-law mathematical equation better than the Bingham plastic or any other two-parameter model. Power-law fluids can be described mathematically as follows: 
3637Bingham plastic model, centipoise, direct-indicating viscometer, Herschel-Bulkley fluid, Newtonian fluid, non-Newtonian fluid, plastic fluid, pseudoplastic, rheological property, rheology, shear rate, shear stress, viscosity, XC polymer
3638None
3639None
3640--
3641propylene glycol normal propyl ether
36421.n. [Drilling Fluids]
3643A solvent used with water to break the emulsion of an oil-base or synthetic-base drilling fluid to prepare the sample for chemical titrations to determine lime, calcium or chloride content according to API testing procedures. PNP is an abbreviation for propylene glycol normal propyl ether. It is an environmentally friendlier replacement of a xylene-isopropynol mixture previously used in certain titrations.
3644isopropanol, xylene
3645None
3646PNP
3647--
3648pay
36491.n. [Geology]
3650A reservoir or portion of a reservoir that contains economically producible hydrocarbons. The term derives from the fact that it is capable of "paying" an income. Pay is also called pay sand or pay zone. The overall interval in which pay sections occur is the gross pay; the smaller portions of the gross pay that meet local criteria for pay (such as minimum porosity, permeability and hydrocarbon saturation) are net pay.
3651hydrocarbon, permeability, porosity, reservoir, sand
3652None
3653None
3654--
3655pipe trip
36561.n. [Drilling]
3657The act of pulling thedrillstringout of the hole or replacing it in the hole. A pipe trip is usually done because thebithas dulled or has otherwise ceased to drill efficiently and must be replaced.
3658monkey board, round trip, short trip
3659tripping pipe
3660None
3661--
3662pozzolan
36631.n. [Drilling Fluids]
3664A siliceous or siliceous and aluminous material that possesses little or no cementitious value. In a finely divided form and in the presence of moisture, however, pozzolan reacts chemically with calcium hydroxide to form compounds possessing cementitious properties.
3665None
3666None
3667None
3668--
3669proration unit
36701.n. [Oil and Gas Business]
3671The amount of acreage, determined by governmental authority that can be efficiently and economically drained by a well at a particular depth or horizon.
3672communitization, pooling, unitization
3673None
3674None
3675--
3676payout
36771.n. [Oil and Gas Business]
3678The point at which all costs of leasing, exploring, drilling and operating have been recovered from production of a well or wells as defined by contractual agreement.
3679back-in, cost oil, production sharing contract, profit oil
3680None
3681None
3682--
3683pipeline capacity
36841.n. [Production Facilities]
3685The quantity (volume) of oil and gas required to maintain a full pipeline. The static capacity of a pipeline is usually expressed as a volume per unit length (for example, bbl/ft). Nevertheless, the fluid volume passing through a pipeline in a specific time period will depend on initial pressure, flow characteristics, ground elevation, density and delivery pressure.
3686None
3687None
3688None
3689--
3690pozzolanic
36911.adj. [Drilling Fluids]
3692Pertaining to material that possesses little or no cementitious value, but that is capable of reacting chemically with calcium hydroxide at ordinary temperatures to form compounds with cementitious properties.
3693None
3694None
3695None
3696--
3697prospect
36981.n. [Geology]
3699An area of exploration in which hydrocarbons have been predicted to exist in economic quantity. A prospect is commonly an anomaly, such as a geologic structure or a seismic amplitude anomaly, that is recommended by explorationists for drilling a well. Justification for drilling a prospect is made by assembling evidence for an active petroleum system, or reasonable probability of encountering reservoir-quality rock, a trap of sufficient size, adequate sealing rock, and appropriate conditions for generation and migration of hydrocarbons to fill the trap. A single drilling location is also called a prospect, but the term is more properly used in the context of exploration. A group of prospects of a similar nature constitutes a play.
3700amplitude anomaly, anomaly, basin, exploration, fairway, generation, hydrocarbon, migration, petroleum system, play, reservoir, seal, source rock, structure, subsalt, trap
3701None
3702None
3703--
3704pdc bit
37051.n. [Drilling]
3706A drilling tool that uses polycrystalline diamond compact (PDC) cutters to shear rock with a continuous scraping motion. These cutters are synthetic diamond disks about 1/8-in. thick and about 1/2 to 1 in. in diameter. PDC bits are effective at drilling shale formations, especially when used in combination with oil-base muds.
3707antiwhirl bit, bit, core
3708drag bit, fixed-cutter bit
3709polycrystalline diamond compact bit
3710--
3711pit
37121.n. [Drilling]
3713Also known as pressure integrity test or leakoff test, a test to determine the strength or fracture pressure of the open formation, usually conducted immediately after drilling below a new casing shoe. During the test, the well is shut in and fluid is pumped into the wellbore to gradually increase the pressure that the formation experiences. At some pressure, fluid will enter the formation, or leak off, either moving through permeable paths in the rock or by creating a space by fracturing the rock. The results of the leakoff test dictate the maximum pressure or mud weight that may be applied to the well during drilling operations. To maintain a small safety factor to permit safe well control operations, the maximum operating pressure is usually slightly below the leakoff test result.
3714casing shoe, formation fracture pressure, fracture gradient, leakoff, mud weight
3715leakoff test, pressure integrity test
3716LOT
3717--
3718ppa
37191.n. [Drilling Fluids]
3720A specialized apparatus used in the particle-plugging test. The PPA is used to determine the ability of particles in the drilling fluid to effectively bridge the pores in the filter medium and, therefore, the ability of the mud to reduce formation damage in the reservoir. The apparatus resembles a high-pressure, high-temperature filtration cell that has been modified to operate upside down (to remove the effects of gravity) and to accept filter media of different permeabilities (sintered metal, which is chosen for higher temperature conditions, aloxite, which is a porous ceramic material, or rock). The medium is selected to match the permeability of the reservoir to be drilled. The filter medium is at the top so that sediment will not affect the filter cake. Pressure is applied hydraulically from below.
3721sintered
3722None
3723particle-plugging apparatus
3724--
3725proximity log
37261.n. [Formation Evaluation]
3727An electrode device with small spacings from which the current flow, and hence the measurement, is focused a short distance into the formation. The proximity log measures the resistivity of the flushed zone with minimum influence from the mudcake or the undisturbed zone. The central current-emitting electrode (A0) is surrounded by a guard electrode that emits sufficient current to focus the current from A0 a certain distance into the formation. The electrodes are mounted on a pad that is pressed against the borehole wall. In a typical tool design, 90% of the signal comes from within 5 to 10 in. [13 to 25 cm] of the pad. This is deeper than the microlaterolog, which ensures that the mudcake has less effect but means that the proximity log is more often affected by the undisturbed zone.
3728electrode resistivity, flushed zone, microresistivity, undisturbed zone
3729None
3730None
3731--
3732peak
37331.n. [Geophysics]
3734The maximum positive or upward deflection, also known as the crest, of the seismic wavelet. The trough is the maximum negative amplitude or downward deflection of the wave. Seismic interpreters commonly pick or interpret seismic data on paper sections along the trough of a wavelet rather than the normally solid-filled peak for ease of viewing.
3735amplitude, polarity, polarity standard, wave, wavelet
3736crest
3737Antonyms:trough
3738--
3739pitot tube
37401.n. [Production Testing]
3741A measuring device for determining the gas-flow rate. It is composed of a 1/8-inch tube inserted horizontally along the axis of the gas flowline. The pressure at the end of the tube is compared with the static pressure to determine the final gas flow rate within the flow line.
3742annubar, flowline, static pressure
3743None
3744None
3745--
3746ppb
37471.n. [Drilling Fluids]
3748Abbreviation for the USoilfieldunit of concentration, pounds per barrel, more correctly written as lbm/bbl. One lbm/bbl is the equivalent of one pound of additive in 42 US gallons ofmud. The "m" is used to denote mass to avoid possible confusion with pounds force (denoted by "lbf"). In SI units, the conversion factor is one pound per barrel equals 2.85 kilograms per cubic meter. For example, 10 lbm/bbl = 28.5 kg/m3.
3749barrel equivalent
3750None
3751lb/bbl, lbm/bbl, pounds per barrel
3752--
3753ppb
37542.n. [Drilling Fluids]
3755Abbreviation for concentration, parts-per-billion. For example, lead in a water sample may be 10 ppb.
3756None
3757None
3758parts per billion
3759--
3760pseudogeometrical factor
37611.n. [Formation Evaluation]
3762The response of a logging measurement as a function of distance from the tool. The pseudogeometrical factor is normally radial, reflecting the response perpendicular to the tool. It can be a differential factor, which is the contribution to the signal at a particular distance, but is more normally integrated, which is the sum of all signals from the tool to a particular distance.The pseudogeometrical factor developed from the concept of the geometrical factor, and is expressed in the same way. For example, for a radial distance x from the tool, the integrated radial pseudogeometrical factor, Jx, can be written as:	Jx = (Ux - Ut) / (Uxo - Ut)where Ut is the log reading of the undisturbed zone (or, alternatively, the reading with no invasion), Uxo is the log reading of the flushed zone (or, alternatively, the reading with infinite invasion), and Ux is the log reading with a step profile invasion to depth x. Unlike the geometrical factor, Jx depends on the values of both Uxo and Ut. Pseudogeometrical factors are a useful way to express the radial response (or vertical response) in typical conditions. The physics of each measurement determines how much Jx varies with Uxo and Ut.Pseudogeometrical factors are often used to express the response of nuclear and resistivity logs, but are not appropriate for acoustic and electromagnetic propagation logs (where the response is too dependent on the contrast in properties), or nuclear magnetic resonance logs (where the response is too localized).
3763depth of investigation, radial resolution, resistivity log, vertical resolution
3764None
3765None
3766--
3767pef
37681.n. [Formation Evaluation]
3769A log of photoelectric absorption properties. The log measures the photoelectric absorption factor, Pe, which is defined as (Z/10) 3.6 where Z is the average atomic number of the formation. Pe is unitless, but since it is proportional to the photoelectric cross section per electron, it is sometimes quoted in barns/electron. Since fluids have very low atomic numbers, they have very little influence, so that Pe is a measure of the rock matrix properties. Sandstones have low Pe, while dolomites and limestones have high Pe. Clays, heavy minerals and iron-bearing minerals have high Pe. Thus, the log is very useful for determining mineralogy. In interpretation, PEF is normally converted to the simpler volumetric cross section, U in barns/cm3, by taking the product of PEF and density.The log is recorded as part of the density measurement. The depth of investigation is of the order of one inch, which is normally in the flushed zone. PEF can be affected by heavy minerals such as barite in the mudcake or mud filtrate. PEF logs were introduced in the late 1970s.
3770azimuthal density, density measurement, flushed zone, photoelectric effect
3771None
3772None
3773--
3774pitting
37751.n. [Enhanced Oil Recovery]
3776A type of corrosion in which there is loss of metal in localized areas. The corrosion rate in the pits is many times greater than the corrosion rate on the entire surface.The resultant pits can be large and shallow or narrow and deep. Pitting is a more dangerous problem than general corrosion because the pitted areas can be easily penetrated.
3777corrosion control
3778None
3779None
3780--
3781ppg
37821.n. [Drilling Fluids]
3783Abbreviation for density, pounds-per-gallon, more correctly written lbm/gal. For example, the density of water is 8.33 ppg at 60°F [16°C].
3784None
3785None
3786None
3787--
3788pseudoplastic
37891.adj. [Drilling Fluids]
3790A descriptive term for a fluid with shear-thinning characteristics that does not exhibit thixotropy. Most effective drilling fluids are shear thinning, although most also exhibit some gel-building characteristics. Pseudoplastic rheology, low viscosity at high shear rates and high viscosity at low shear rates, benefits several aspects of drilling-higher drilling rate and improved cuttings lifting. Bingham plastic fluids, power-law fluids and Herschel-Bulkley fluids fall in the psuedoplastic category of rheology.
3791Bingham plastic model, Herschel-Bulkley fluid, hydroxyethylcellulose, non-Newtonian fluid, plastic fluid, power-law fluid, shear rate, shear stress, thixotropy, viscosity, XC polymer
3792None
3793None
3794--
3795peg leg multiple
37961.n. [Geophysics]
3797A type of short-path multiple, or multiply-reflected seismic energy, having an asymmetric path. Short-path multiples are added to primary reflections, tend to come from shallow subsurface phenomena and highly cyclical deposition, and can be suppressed by seismic processing. In some cases, the period of the peg-leg multiple is so brief that it interferes with primary reflections, and its interference causes a loss of high frequencies in the wavelet.
3798event, long-path multiple, multiple reflection, noise, primary reflection, processing, short-path multiple
3799None
3800None
3801--
3802plastic deformation
38031.n. [Geology]
3804Permanent mechanical or physical alteration that does not include rupture. Plastic deformation of rocks typically occurs at high temperatures and pressures, conditions under which rocks become relatively viscous.
3805elastic deformation, plastic, rheology
3806None
3807None
3808--
3809precipitate
38101.vb. [Drilling Fluids]
3811To form an insoluble material in a fluid. Precipitation can occur by a chemical reaction of two or more ions in solution or by changing the temperature of a saturated solution. There are many examples of this important phenomenon in drilling fluids. Precipitation occurs in the reaction between calcium cations and carbonate anions to form insoluble calcium carbonate: Ca+2 + CO3-2 --&gt; CaCO3. When a saturated clear brine first crystallizes, the solid is a precipitate, and is often caused by changing temperature.
3812drilling fluid, oxygen scavenger, saturated solution, scale, scavenger, sequestering agent, sulfide scavenger
3813None
3814None
3815--
3816precipitate
38172.n. [Enhanced Oil Recovery]
3818A reaction by-product. In sandstone acidizing, the reaction between hydrofluoric acids [HF] or spent HF acids with formation minerals can precipitate nondamaging products, such as silica, borosilicates or fluoborates. However, other insoluble or difficult to remove by-products can create formation damage.Ferric iron (Fe+3) and ferrous iron (Fe+2) are potential sources for precipitates. Ferric iron present in some formation minerals, including chlorite and glauconite clays, and in tubing rust (iron oxide) can precipitate as ferric hydroxide [Fe(OH)3], which is a gelatinous, highly insoluble mass that can plug pore channels and reduce permeability. The precipitation of ferric hydroxide or ferrous hydroxide [Fe(OH)2] depends on the pH of the spent acid. The former needs a pH higher than 2.2, while the latter requires a pH higher than 7.7. Since the maximum pH for a spent acid is approximately 5.3, the precipitation of ferric hydroxide is more common. Iron-sequestering or iron-reducing agents can be used in acid to maintain the ferric iron in solution.Calcium fluoride [CaF2] precipitates when HF contacts calcite or any other calcium source, and alkali-fluosilicates or iron sulfide form crystal-like by-products that can bridge pore throats. Additionally, some sequestering agents, corrosion inhibitors or friction reducers can also form residues that may plug formation pores.The formation of precipitates can be avoided or reduced by using a preflush, which dissolves calcareous material, iron rust or iron scales, and displaces formation brines (K, Na, Ca ions) away from the wellbore, thereby reducing the formation of CaF2, ferric hydroxide and alkali-fluosilicates.
3819None
3820None
3821None
3822--
3823pseudopressure plot
38241.n. [Well Testing]
3825A plot of real gas pseudopressure (pseudopotential) m(p) versus time function used to analyze gas-well drawdown and buildup tests. The use of the real gas pseudopressure linearizes the diffusion equation for gas flow. This form enables rigorous analysis over all pressure ranges. The pressure-squared plot can be used for low pressure (p &lt; ~2000 psi), and pressure can be used to analyze gas-well tests at high pressure (p &gt; ~3000 psi).
3826buildup test, drawdown test, pressure-squared plot
3827None
3828None
3829--
3830peg leg multiple
38311.n. [Geophysics]
3832A type of short-path multiple, or multiply-reflected seismic energy, having an asymmetric path. Short-path multiples are added to primary reflections, tend to come from shallow subsurface phenomena and highly cyclical deposition, and can be suppressed by seismic processing. In some cases, the period of the peg-leg multiple is so brief that it interferes with primary reflections, and its interference causes a loss of high frequencies in the wavelet.
3833event, long-path multiple, multiple reflection, noise, primary reflection, processing, short-path multiple
3834None
3835None
3836--
3837plate tectonics
38381.n. [Geology]
3839The unifying geologic theory developed to explain observations that interactions of the brittle plates of the lithosphere with each other and with the softer underlying asthenosphere result in large-scale changes in the Earth. The theory of plate tectonics initially stemmed from observations of the shapes of the continents, particularly South America and Africa, which fit together like pieces in a jigsaw puzzle and have similar rocks and fossils despite being separated by a modern ocean. As lithospheric plates heat up or cool down depending on their position, or their tectonic environment, relative to each other and to warmer areas deeper within the Earth, they become relatively more or less dense than the asthenosphere and thus tend to rise as molten magma or sink in cold, brittle slabs or slide past each other. Mountain belts can form during plate collisions or an orogeny; diverging plates or rifts can create new midoceanic ridges; plates that slide past one another create transform fault zones (such as the San Andreas fault); and zones of subduction occur where one lithospheric plate moves beneath another. Plate tectonic theory can explain such phenomena as earthquakes, volcanic or other igneous activity, midoceanic ridges and the relative youth of the oceanic crust, and the formation of sedimentary basins on the basis of their relationships to lithospheric plate boundaries. Convection of the mantle is postulated to be the driving mechanism for the movement of lithospheric plates. Measurements of the continents using the Global Positioning System confirm the relative motions of plates. Age determinations of the oceanic crust confirm that such crust is much younger than that of the continents and has been recycled by the process of subduction and regenerated at midoceanic ridges.
3840active margin, aulacogen, basin, core, craton, earthquake, eustasy, Global Positioning System, isostasy, midoceanic ridge, normal fault, orogeny, passive margin, preservation, rift, rock, sedimentary basin, sequence stratigraphy, tectonism, transform fault, Wadati-Benioff zone
3841tectonics
3842None
3843--
3844precipitation
38451.n. [Drilling Fluids]
3846The formation of an insoluble material in a fluid. Precipitation can occur by a chemical reaction of two or more ions in solution or by changing the temperature of a saturated solution. There are many examples of this important phenomenon in drilling fluids. Precipitation occurs in the reaction between calcium cations and carbonate anions to form insoluble calcium carbonate: Ca+2 + CO3-2 --&gt; CaCO3. When a saturated clear brine first crystallizes, the solid is a precipitate, and is often caused by changing temperature.
3847drilling fluid, oxygen scavenger, saturated solution, scale, scavenger, sequestering agent, sulfide scavenger
3848None
3849None
3850--
3851pseudostatic spontaneous potential
38521.n. [Formation Evaluation]
3853The ideal spontaneous potential (SP) that would be observed opposite a shaly, permeable bed if the SP currents were prevented from flowing. In the middle of a thick, permeable bed whose resistivity is not too high, the SP reads close to the pseudostatic spontaneous potential (PSP). In other conditions, however, the SP may be significantly less than the PSP. The PSP ignores other potential sources and assumes that a surrounding shale is a perfect cationic membrane. The ratio of the PSP to the static spontaneous potential is known as the SP reduction factor, alpha. Alpha is less than 1 and is a function of the shaliness, or cation-exchange capacity, within the sand. The higher this cation-exchange capacity, the larger the internal membrane potential. The latter has the opposite polarity to the liquid-junction potential and reduces the SP.The PSP, and alpha, are reduced when hydrocarbons are introduced into shaly sands, because the cation-exchange capacity in the sands is forced into a smaller conductive pore volume and therefore has a larger relative effect.
3854cation-exchange capacity, electrokinetic potential, hydrocarbon, liquid-junction potential, membrane potential, shale baseline, spontaneous potential
3855SP
3856PSP
3857--
3858pendant drop tensiometer
38591.n. [Enhanced Oil Recovery]
3860A standard laboratory instrument used to measure interfacial tension. The method is particularly applicable to relatively high interfacial tensions, but with care can measure down to approximately 1 mN/m. A drop of the denser liquid is poised at the end of a square-ended syringe needle. The drop is of sufficient size that its shape is deformed by gravity, but not so large that it detaches from the syringe. Its shape is determined by the balance of interfacial tension and gravity. The interfacial tension can be obtained from the drop shape and the densities of the two liquids. The method works equally well for a drop of the less-dense liquid by inverting the syringe. This inverted configuration can be useful if the less-dense liquid is opaque.
3861interfacial tension, spinning-drop tensiometer
3862None
3863None
3864--
3865play
38661.n. [Shale Gas, Geology]
3867An area in which hydrocarbon accumulations or prospects of a given type occur.For example the shale gas plays in North America include the Barnett, Eagle Ford, Fayetteville, Haynesville, Marcellus, and Woodford, among many others. Outside North America, shale gas potential is being pursued in many parts of Europe, Africa, Asia, and South America.
3868accumulation, anomaly, basin, deep-water play, exploration, fairway, hydrocarbon, petroleum system, prospect, subsalt, trend
3869None
3870None
3871--
3872play
38732.n. [Geology, Shale Gas]
3874A conceptual model for a style of hydrocarbon accumulation used by explorationists to develop prospects in a basin, region or trend and used by development personnel to continue exploiting a given trend. A play (or a group of interrelated plays) generally occurs in a single petroleum system.
3875accumulation, anomaly, basin, deep-water play, development, exploration, fairway, hydrocarbon, petroleum system, prospect, reservoir, source rock, subsalt
3876None
3877None
3878--
3879play
38803.vt. [Geology]
3881To pursue hydrocarbon accumulations of a given type.
3882accumulation, exploration play, hydrocarbon
3883None
3884None
3885--
3886precision
38871.n. [Formation Evaluation]
3888The closeness of agreement between the results obtained by applying a measurement procedure several times on identical materials and under prescribed measurement conditions. The smaller the random part of experimental error, the more precise the measurement procedure. (ISO)In logging, the term usually describes the repeatability of a statistical measurement, such as a nuclear log. The precision must then refer to a particular set of conditions, for example, the speed of logging and the formation properties.
3889accuracy, alpha processing, reproducibility
3890None
3891None
3892--
3893pull up
38941.n. [Geophysics]
3895A phenomenon of relative seismic velocities of strata whereby a shallow layer or feature with a high seismic velocity (e.g., a salt layer or salt dome, or a carbonate reef) surrounded by rock with a lower seismic velocity causes what appears to be a structural high beneath it. After such features are correctly converted from time to depth, the apparent structural high is generally reduced in magnitude.
3896depth conversion, salt dome, velocity anomaly
3897None
3898Antonyms:push-down
3899--
3900penetration rate
39011.n. [Drilling]
3902The speed at which the drill bit can break the rock under it and thus deepen the wellbore. This speed is usually reported in units of feet per hour or meters per hour.
3903antiwhirl bit, drill bit
3904None
3905None
3906--
3907plug and abandon
39081.vb. [Drilling]
3909To prepare a well to be closed permanently, usually after either logs determine there is insufficient hydrocarbon potential to complete the well, or after production operations have drained the reservoir. Different regulatory bodies have their own requirements for plugging operations. Most require that cement plugs be placed and tested across any open hydrocarbon-bearing formations, across all casing shoes, across freshwater aquifers, and perhaps several other areas near the surface, including the top 20 to 50 ft [6 to 15 m] of the wellbore. The well designer may choose to set bridge plugs in conjunction with cement slurries to ensure that higher density cement does not fall in the wellbore. In that case, the bridge plug would be set and cement pumped on top of the plug through drillpipe, and then the drillpipe withdrawn before the slurry thickened.
3910bridge plug, casing shoe, cement, cementing, operator
3911None
3912P&amp;A
3913--
3914plug and abandon
39152.vb. [Well Completions]
3916To prepare a wellbore to be shut in and permanently isolated. There are typically regulatory requirements associated with the P&amp;A process to ensure that strata, particularly freshwater aquifers, are adequately isolated. In most cases, a series of cement plugs is set in the wellbore, with an inflow or integrity test made at each stage to confirm hydraulic isolation.
3917None
3918None
3919P&amp;A
3920--
3921preflush
39221.n. [Enhanced Oil Recovery]
3923A fluid stage, normally hydrochloric acid [HCl], pumped ahead of the main treating fluid (mixture of hydrofluoric [HF] and hydrochloric [HCl] or organic acids) in a sandstone matrix-stimulation treatment. One of the purposes of a preflush is to displace formation brines that contain K, Na, Ca ions away from the wellbore, decreasing the possibility of crystallizing alkali-fluosilicates that could plug the pores. The other purpose of a preflush is to dissolve calcareous materials to minimize calcium fluoride [CaF2] precipitation, and to dissolve iron scale or rust to avoid the precipitation of the gelatinous, highly insoluble ferric hydroxide [Fe(OH)3].Multiple preflush stages using brines such as ammonium chloride [NH4Cl] or solvents are used when multiple damage types are present. A preflush is sometimes called a spearhead.
3924hydrochloric acid, matrix stimulation, overflush, precipitate
3925None
3926None
3927--
3928preflush
39292.n. [Enhanced Oil Recovery]
3930In chemical flooding, a fluid stage, normally low-salinity water, pumped ahead of the micellar or alkaline chemical solution.One of the purposes of the preflush is to displace reservoir brine containing potassium, sodium, calcium and magnesium ions from the near-wellbore area, avoiding adverse interactions with the chemical solution. The other purposes are to adjust reservoir salinity to favorable conditions for the surfactant (chemical solution) and to obtain information about reservoir flow patterns. Sometimes a preflush stage is not necessary, especially when brine-tolerant chemical systems are used.
3931None
3932None
3933None
3934--
3935pulling tool
39361.n. [Well Workover and Intervention]
3937A slickline or coiled tubing tool used to retrieve temporary devices, such as plugs and flow-control equipment, from the wellbore. Pulling tools are available in a range of sizes and profiles and must be compatible with the equipment to be retrieved. A contingency release system in the pulling tool allows the tool to be released and retrieved if the equipment to be retrieved cannot be released.
3938None
3939None
3940None
3941--
3942perforated liner
39431.n. [Perforating]
3944A wellbore tubular in which slots or holes have been made before the string is assembled and run into the wellbore. Perforated liners typically are used in small-diameter wellbores or in sidetracks within the reservoir where there is no need for the liner to be cemented in place, as is required for zonal isolation.
3945liner
3946None
3947None
3948--
3949plug flow
39501.n. [Production Logging]
3951A multiphase flow regime in pipes in which most of the gas moves as large bubbles dispersed within a continuous liquid. The bubbles may span much of the pipe. There are also small bubbles within the liquid, but many of these have coalesced to form the larger bubbles, or plugs. In near-horizontal wells, the plugs are also known as elongated bubbles. Plug flow is similar to slug flow, but the bubbles are generally smaller and move more slowly.
3952bubble flow, flow structure, multiphase flow, slug flow
3953None
3954None
3955--
3956prehydrate
39571.vb. [Drilling Fluids]
3958To mix with water and allow to react or yield in the water before use. Prehydrating is a common technique for incorporating bentonite in cement slurry or drilling mud. Prehydration may also be done for convenience in cementing operations to allow mixing of water containing the additives with powdered neat cement. Additives also may be prehydrated with mix water to avoid dry-blending the additives with cement.
3959None
3960None
3961None
3962--
3963pull up
39641.n. [Geophysics]
3965A phenomenon of relative seismic velocities of strata whereby a shallow layer or feature with a high seismic velocity (e.g., a salt layer or salt dome, or a carbonate reef) surrounded by rock with a lower seismic velocity causes what appears to be a structural high beneath it. After such features are correctly converted from time to depth, the apparent structural high is generally reduced in magnitude.
3966depth conversion, salt dome, velocity anomaly
3967None
3968Antonyms:push-down
3969--
3970perforating charge
39711.n. [Perforating]
3972An explosive device that utilizes a cavity-effect explosive reaction to generate a high-pressure, high-velocity jet that creates a perforation tunnel. The shape of the explosive material and powdered metal lining determine the shape of the jet and performance characteristics of the charge. The extremely high pressure and velocity of the jet cause materials, such as steel, cement and rock formations, to flow plastically around the jet path, thereby creating the perforation tunnel.
3973perforating gun
3974shaped charge
3975None
3976--
3977plug valve
39781.n. [Production]
3979A quarter-turn valve whose closure element is usually a tapered plug having a rectangular port.
3980None
3981None
3982None
3983--
3984premium thread
39851.n. [Well Completions]
3986A class of high-performance thread types that are commonly used in modern oilwell and gaswell completions. Premium threads are available in a number of configurations and are typically designed to provide superior hydraulic sealing, improved tensile capacity and ease of make-up. Unlike conventional threads, the sealing areas in premium thread connections are independent of the thread profile and are included as two or three areas within the tool joint, thereby providing some redundancy.
3987tool joint
3988None
3989None
3990--
3991pulse echo
39921.n. [Formation Evaluation]
3993A technique in which an ultrasonic transducer, in transmit mode, emits a high-frequency acoustic pulse towards the borehole wall, where it is reflected back to the same transducer operating in receive mode. The measurement consists of the amplitude of the received signal, the time between emission and reception, and sometimes the full waveform received. Tools that use this technique either have multiple transducers, facing in different directions, or rotate the transducer while making measurements, thereby obtaining a full image of the borehole wall. Pulse-echo techniques are used in the borehole televiewer. In cased hole, the waveform is analyzed to give indications of cement-bond quality and casing corrosion.
3994ultrasonic measurement
3995None
3996None
3997--
3998perforating depth control log
39991.n. [Perforating]
4000A wireline log run to provide a means of depth correlation by comparing the position of casing collars to the reference log (gamma ray log). A short casing joint generally is run near the area to be perforated to assist in the correlation process.
4001casing collar, casing joint, depth correlation, gamma ray log, wireline log
4002None
4003None
4004--
4005plunger lift
40061.n. [Well Completions]
4007An artificial-lift method principally used in gas wells to unload relatively small volumes of liquid. An automated system mounted on the wellhead controls the well on an intermittent flow regime. When the well is shut-in, a plunger is dropped down the production string. When the control system opens the well for production, the plunger and a column of fluid are carried up the tubing string. The surface receiving mechanism detects the plunger when it arrives at surface and, through the control system, prepares for the next cycle.
4008production string
4009None
4010None
4011--
4012plunger lift
40132.n. [Production Testing]
4014A type of gas-lift method that uses a plunger that goes up and down inside the tubing. The plunger provides an interface between the liquid phase and the lift gas, minimizing liquid fallback. The plunger has a bypass valve that opens at the top of the tubing and closes when it reaches the bottom. Plunger-lift methods are used to remove water and condensate from a well, but they can handle only a limited column of liquid. Typically, these methods are applied on gas wells with high gas liquid ratio (GLR) to operate only with formation gas.
4015None
4016None
4017None
4018--
4019preservative
40201.n. [Drilling Fluids]
4021Another term for bactericide, an additive that kills bacteria. Bactericides are commonly used in water muds containing natural starches and gums that are especially vulnerable to bacterial attack. Bactericide choices are limited and care must be taken to find those that are effective yet approved by governments and by company policy.Bactericides, also called biocides, can be used to controlsulfate-reducing bacteria,slime-forming bacteria,iron-oxidizing bacteria,and bacteria that attacks polymers in fracture andsecondary recovery fluids. In polymers, the degradation of the fluid is controlled, thus avoiding the formation of a large biomass, which could plug the formation and reducepermeability.
4022anaerobic, bioassay, biocide, formaldehyde, guar gum, LC50, paraformaldehyde, polymer, starch, XC polymer
4023bactericide
4024None
4025--
4026pulsed neutron spectroscopy log
40271.n. [Formation Evaluation]
4028A wireline log of the yields of different elements in the formation, measured using induced gamma ray spectroscopy with a pulsed neutron generator. The elemental yields are derived from two intermediate results: the inelastic and the capture spectrum. The inelastic spectrum is the basis for the carbon-oxygen log, and can also give information on other elements. The capture spectrum depends on many elements, mainly hydrogen, silicon, calcium, iron, sulfur and chlorine. Since the elemental yields give information only on the relative concentration of elements, they are normally given as ratios, such as C/O, Cl/H, Si/(Si + Ca), H/(Si + Ca) and Fe/(Si + Ca). These ratios are indicators of oil, salinity, lithology, porosity and clay, respectively. To get absolute concentrations, it is necessary to calibrate to cores or, more often, use a model such as the oxide-closure model.The depth of investigation of the log is several inches into the formation. It can be run in open or cased hole. Pulsed neutron spectroscopy logs were introduced in the mid 1970s after a decade or more of investigation.
4029activation log, alpha processing, elemental capture spectroscopy, geochemical log, induced gamma ray spectroscopy, neutron interactions, oxide-closure model, pulsed neutron spectroscopy measurement, wireline log
4030None
4031None
4032--
4033perforating depth control log
40341.n. [Perforating]
4035A wireline log run to provide a means of depth correlation by comparing the position of casing collars to the reference log (gamma ray log). A short casing joint generally is run near the area to be perforated to assist in the correlation process.
4036casing collar, casing joint, depth correlation, gamma ray log, wireline log
4037None
4038None
4039--
4040pnp
40411.n. [Drilling Fluids]
4042A solvent used with water to break the emulsion of an oil-base or synthetic-base drilling fluid to prepare the sample for chemical titrations to determine lime, calcium or chloride content according to API testing procedures. PNP is an abbreviation for propylene glycol normal propyl ether. It is an environmentally friendlier replacement of a xylene-isopropynol mixture previously used in certain titrations.
4043chloride test
4044None
4045propylene glycol normal propyl ether
4046--
4047preserved core
40481.n. [Formation Evaluation]
4049A core that has been preserved in the same state as when it was brought to the surface. The term implies that the core has been stored for a period before analysis. If this has not been the case, it is known as fresh core. The goal of preservation is to maintain the original fluid content, fluid distribution, rock wettability and mechanical integrity. Preserved cores are typically sealed and protected from mechanical damage. Depending on the core and the objective, they may also be frozen or placed in humidity ovens.Preservation may be wet, in which the core is submerged in a suitably prepared brine, or dry, without any fluid.
4050native state core, restored state core, routine core analysis
4051None
4052None
4053--
4054pulsed neutron spectroscopy measurement
40551.n. [Formation Evaluation]
4056A measurement of the spectrum of gamma rays emitted by a formation bombarded by high-energy neutrons. Neutrons are emitted by a high-energy neutron generator (14.1 MeV). The neutrons interact with different nuclei, which may emit characteristic gamma rays through inelastic neutron scattering, fast-neutron reactions and neutron capture. When pulses from a neutron generator are used, it is possible to separate the different interactions in time after each neutron pulse. Inelastic and fast-neutron interactions occur very soon after the neutron burst, while most of the capture events occur later. The two types can therefore be separated to give a so-called inelastic spectrum and a capture spectrum. The spectra are analyzed either by counting gamma rays in windows placed at the main peaks for the elements concerned, or by comparison with spectral standards, or by combining the two (alpha processing).The resultant logs are known as pulsed neutron spectroscopy logs, the most common of which are the carbon-oxygen log and the elemental capture spectroscopy log.
4057activation log, geochemical log, neutron interactions, oxide-closure model, pulsed neutron spectroscopy log
4058None
4059None
4060--
4061perforating fluid
40621.n. [Perforating, Well Completions]
4063A specially prepared fluid placed in the wellbore over the interval to be perforated. The ideal fluid is clean and solids-free (filtered), and will not react to cause damaging by-products on contact with the reservoir formation. Perforating in a dirty fluid may result in significant permeability damage that is difficult to treat and remove.
4064None
4065None
4066None
4067--
4068point bar
40691.n. [Geology]
4070An arcuate deposit of sediment, usually sand, that occurs along the convex inner edges of the meanders of channels and builds outward as the stream channel migrates.
4071channel, depositional environment, sand, sediment
4072None
4073None
4074--
4075pressure
40761.n. [Well Testing]
4077The force distributed over a surface, usually measured in pounds force per square inch, or lbf/ in.2, or psi, in US oilfield units.
4078None
4079None
4080None
4081--
4082pulse echo
40831.n. [Formation Evaluation]
4084A technique in which an ultrasonic transducer, in transmit mode, emits a high-frequency acoustic pulse towards the borehole wall, where it is reflected back to the same transducer operating in receive mode. The measurement consists of the amplitude of the received signal, the time between emission and reception, and sometimes the full waveform received. Tools that use this technique either have multiple transducers, facing in different directions, or rotate the transducer while making measurements, thereby obtaining a full image of the borehole wall. Pulse-echo techniques are used in the borehole televiewer. In cased hole, the waveform is analyzed to give indications of cement-bond quality and casing corrosion.
4085ultrasonic measurement
4086None
4087None
4088--
4089perforating gun
40901.n. [Perforating]
4091A device used to perforate oil and gas wells in preparation for production. Containing several shaped explosive charges, perforating guns are available in a range of sizes and configurations. The diameter of the gun used is typically determined by the presence of wellbore restrictions or limitations imposed by the surface equipment.
4092casing gun, expendable gun, high-shot density gun
4093None
4094None
4095--
4096polar
40971.adj. [Drilling Fluids]
4098In chemistry, referring to a compound in which electrons are not shared equally in the chemical bond, resulting in partial electrical charges. The best example is water, H2O, where the oxygen atom "pulls" the electrons more strongly than the hydrogen atoms and has a partial negative charge. The hydrogen atoms thus carry a partial positive charge. Polar compounds may ionize partially when dissolved in water.
4099cation, sulfonated asphalt, vinyl acetate-maleic anhydride copolymer
4100None
4101None
4102--
4103pressure buildup
41041.n. [Well Testing]
4105A rise in well pressure as a function of time observed after a well is shut in or after the production rate is reduced. Buildup pressures are normally measured at or near the bottom of the hole.
4106None
4107None
4108Antonyms:pressure drawdown
4109--
4110pump manifold
41111.n. [Well Workover and Intervention]
4112The arrangement of lines and valves used to direct and control fluid on a pumping unit. The manifold on the pump suction is generally known as the inlet or low-pressure manifold. The corresponding manifold located on the pump discharge is commonly known as the high-pressure or discharge manifold. In most cases, reference to the pump manifold relates to the high-pressure manifold.
4113None
4114None
4115None
4116--
4117perforation phasing
41181.n. [Perforating]
4119The radial distribution of successive perforating charges around the gun axis. Perforating gun assemblies are commonly available in 0-, 180-, 120-, 90- and 60-degree phasing. The 0-degree phasing is generally used only in small outside-diameter guns, while 60, 90 and 120 degree phase guns are generally larger but provide more efficient flow characteristics near the wellbore.
4120perforating gun
4121None
4122None
4123--
4124polar compound
41251.n. [Drilling Fluids]
4126A compound whose electrons are not shared equally in chemical bonds. A polar compound is not necessarily ionized. Water is a polar compound. Polymers can have ionizing polar groups on their complex structures.
4127anion, asphaltic mud additive, cation, clay, clay extender, deflocculant, polyelectrolyte, polymer, salt, sulfonated polystyrene-maleic anhydride copolymer
4128None
4129None
4130--
4131pressure drawdown
41321.n. [Well Completions]
4133The differential pressure that drives fluids from the reservoir into the wellbore. The drawdown, and therefore the production rate, of a producing interval is typically controlled by surface chokes. Reservoir conditions, such as the tendency to produce sand, may limit the drawdown that may be safely applied during production before damage or unwanted sand production occurs.
4134None
4135None
4136None
4137--
4138pressure drawdown
41392.n. [Well Testing]
4140A decline in well pressure with time due to production.
4141None
4142None
4143None
4144--
4145pumpability
41461.n. [Drilling Fluids]
4147The ability of the slurry to be pumped. Pumpability is usually measured by the API thickening-time test.
4148None
4149None
4150None
4151--
4152permanent datum
41531.n. [Formation Evaluation]
4154The level to which all subsurface depths in an area are referred, normally the mean sea level. In individual wells, the depth is measured from the depth reference. However, in order to compare data between wells it is important to have a valid, area wide reference for comparison. This is the permanent datum level.
4155depth wheel, first reading, last reading, log
4156None
4157None
4158--
4159polarization horn
41601.n. [Formation Evaluation]
4161The effect on a propagation resistivity or induction log of charge buildup at the boundary between two formation layers with different dielectric properties. In a vertical well with horizontal layers, the current loops generated by the tool in the formation are parallel to the layers and do not cross bed boundaries. However, with an apparent dip between borehole and formation, the loops cross the bed boundaries and generate a charge buildup at the boundaries. The charge buildup acts like a secondary transmitter that increases the measured resistivity. The result is a spike to high resistivity as the tool crosses the bed boundary. In deviated or horizontal wells, polarization horns on measurements-while-drilling propagation logs often are used to detect a bed boundary.The spike increases with apparent dip and resistivity contrast between beds. The magnitude of polarization spikes varies with tool type and spacing, being larger for the propagation tools.
4162attenuation resistivity, dielectric resistivity, phase-shift resistivity, propagation resistivity measurement, relative dielectric permittivity
4163None
4164None
4165--
4166pressure falloff
41671.n. [Well Testing]
4168The pressure decline after halting or reducing fluid injection in a well. Pressure falloff tests in injection wells are analogous to pressure buildup tests in production wells.
4169pressure buildup
4170None
4171None
4172--
4173pumping time
41741.n. [Drilling Fluids]
4175The total time required for pumping the cement slurry into the well, plus a safety factor. Pumping time can also be the time required to reach a consistency deemed to be unpumpable (generally 70 Bc) during an API thickening-time test.
4176None
4177None
4178None
4179--
4180permanent well monitoring
41811.n. [Production Testing]
4182A situation in which the well and the reservoir are continuously monitored. On the basis of this information, the well completion may be adjusted remotely to adapt to changes in downhole conditions. A permanent well monitoring system is composed of the following:·	Inflow control valves that enable choking or shutting off different zones according performance such as drawdown, GOR or water cut ·	Downhole sensors that register pressure, fluid flow rate and temperature·	Control lines for power transmission and transferring of monitored downhole data captured by downhole sensors.·	A surface control unit to handle the monitored data and for remote operation of the downhole inflow control valves.Wells with permanent monitoring systems are commonly called intelligent or smart wells. Permanent well monitoring is commonly used in multilateral wells, where hydraulically independent valves control the flow of each lateral and in deepwater wells, where well-intervention operations are often prohibitively expensive.Permanent well monitoring helps improve reservoir management by quickly choking or shutting off zones, avoiding expensive well intervention. It also helps maximize production and optimize recovery.
4183None
4184None
4185None
4186--
4187polarization time
41881.n. [Formation Evaluation]
4189The time allotted for the alignment of hydrogen atoms with the static magnetic field during a nuclear magnetic resonance (NMR) measurement. The alignment of hydrogen atoms follows an exponential rule such that after a polarization time PT the percentage aligned is 100*(1 ? e-PT/T1) where T1 is their longitudinal relaxation time. An infinite polarization time is therefore needed to align every hydrogen atom, but 95% are aligned after a time of 3*T1. Typical polarization times for a standard NMR log are between 1 and 4 s.
4190nuclear magnetic resonance, nuclear magnetic resonance measurement, wait time
4191None
4192None
4193--
4194pressure gradient
41951.n. [Geology]
4196The change in pressure per unit of depth, typically in units of psi/ft or kPa/m. Pressure increases predictably with depth in areas of normal pressure. The normal hydrostatic pressure gradient for freshwater is 0.433 psi/ft, or 9.792 kPa/m, and 0.465 psi/ft for water with 100,000 ppm total dissolved solids (a typical Gulf Coast water), or 10.516 kPa/m. Deviations from normal pressure are described as high or low pressure.
4197abnormal pressure, formation pressure, geopressure gradient, lithostatic pressure, normal pressure, pore pressure
4198None
4199None
4200--
4201pressure gradient
42022.n. [Well Testing]
4203A change in pressure as a function of distance. This can refer to radial change in pore pressure with distance from the well (which can be calculated from well-test analysis results), to change in pore pressure with depth (which can be measured by formation tests, and implies formation fluid density and/or fluid contacts) or to change in wellbore fluid pressure with depth (which can be measured with production logs, and implies wellbore fluid density).
4204formation fluid, pore pressure, production log
4205None
4206None
4207--
4208pumping well
42091.n. [Well Testing]
4210A well produced by use of some kind of downhole pump. Pumps are required when the formation pressure is not sufficient to allow flowing production of fluids at the desired or necessary rate. The performance of well tests on pumping wells is always complicated by the presence of the pump, which often must be removed to take downhole pressure measurements. Downhole pressure measurements in pumping wells are usually made by measuring the rise in liquid level in the well. This is often accomplished by sonic devices, like well sounders, that measure the response time of sound waves bounced off the downhole liquid surface. Most oil wells are eventually put on pumps as pressure declines during production. The exceptions are in strong waterdrive reservoirs or in settings where pressure maintenance by gas or water injection is sufficient to maintain a high reservoir pressure.
4211None
4212None
4213Antonyms:naturally flowing well
4214--
4215permeability
42161.n. [Geology]
4217The ability, or measurement of a rock's ability, to transmit fluids, typically measured in darcies or millidarcies. The term was basically defined by Henry Darcy, who showed that the common mathematics of heat transfer could be modified to adequately describe fluid flow in porous media. Formations that transmit fluids readily, such as sandstones, are described as permeable and tend to have many large, well-connected pores. Impermeable formations, such as shales and siltstones, tend to be finer grained or of a mixed grain size, with smaller, fewer, or less interconnected pores. Absolute permeability is the measurement of the permeability conducted when a single fluid, or phase, is present in the rock. Effective permeability is the ability to preferentially flow or transmit a particular fluid through a rock when other immiscible fluids are present in the reservoir (for example, effective permeability of gas in a gas-water reservoir). The relative saturations of the fluids as well as the nature of the reservoir affect the effective permeability. Relative permeability is the ratio of effective permeability of a particular fluid at a particular saturation to absolute permeability of that fluid at total saturation. If a single fluid is present in a rock, its relative permeability is 1.0. Calculation of relative permeability allows for comparison of the different abilities of fluids to flow in the presence of each other, since the presence of more than one fluid generally inhibits flow.
4218absolute permeability, cap rock, effective permeability, fracture, fracture porosity, impermeable, pore, pore pressure, porosity, relative permeability, reservoir, saturation, seal
4219None
4220None
4221--
4222permeability
42232.n. [Geophysics]
4224In magnetics, the ratio of the density of the magnetic flux, B (in units of teslas), to the strength of the magnetic field, H (in units of amperes/meter), typically in units of H/m.μ = B / H,whereμ = magnetic permeabilityB = magnetic flux or magnetic inductionH = magnetizing field strength.μ = μ0 = 4π × 10−7 henries per meter (H/m) is the magnetic permeability of free space, or a vacuum. For practical purposes, the magnetic permeability of air or water is μ0.
4225magnetics, skin depth
4226None
4227None
4228--
4229permeability
42303.n. [Well Testing]
4231The capability of a rock to allow passage of fluids through it. The term was basically defined by Darcy, who showed that the common mathematics of heat transfer could be modified to adequately describe fluid flow in porous media.
4232None
4233None
4234None
4235--
4236polished joint
42371.n. [Well Completions]
4238A generic term for a completion component that has been polished or prepared to enable an efficient hydraulic seal. The polished joint may have an internal or external polished surface and is typically configured in a length that enables some movement of the completion string or associated components without compromising the hydraulic seal.
4239None
4240None
4241None
4242--
4243pressure hunt
42441.n. [Drilling]
4245The evaluation of various well parameters in an attempt to identify when the pore pressure in a drilling well is changing. A team consisting of geologists, engineers and most of the rigsite personnel usually conducts the hunt. The purpose of a pressure hunt is to detect the pore pressure transition (usually from lower to higher pressure) and safely set casing in the transition zone to maximize wellbore strength. A casing string set too shallow, while eliminating some problems associated with drilling fluid contacting the wellbore wall, may not add strength or aid in drilling deeper, perhaps abnormally pressured formations. On the other hand, if drilling is continued too deep into a transition zone, a kick may be taken that cannot be contained in the open wellbore, causing an underground blowout. The hunt team, therefore, seeks to get into the transition zone far enough to gain wellbore strength without taking a kick.
4246blowout, casing, casing point, casing string, kick, pore pressure
4247None
4248None
4249--
4250pumping well tests
42511.n. [Well Testing]
4252Testing that is accomplished by measuring pressure in the annulus, or by pulling the pump and running a pressure gauge in the hole. The preferred method is usually to measure the pressure in the annulus if no packer is present. This is best done by monitoring the rise in fluid level with an echo-sounding device and calculating the bottomhole pressure by assuming a fluid density. Several excellent devices and associated services are available. Any time a well is shut in gradually, as is the case for pumping wells, some kind of multirate analysis is usually required to obtain acceptable results.
4253None
4254None
4255None
4256--
4257permeability thickness
42581.n. [Well Testing]
4259The product of formation permeability, k, and producing formation thickness, h, in a producing well, referred to as kh. This product is the primary finding of buildup and drawdown tests and is a key factor in the flow potential of a well. It is used for a large number of reservoir engineering calculations such as prediction of future performance, secondary and tertiary recovery potential, and potential success of well-stimulation procedures. Obtaining the best possible value of this product is the primary objective of transient well tests. To separate the elements of the product, it is necessary to have some independent measurement of one of them, usually the estimation of producing formation thickness from well logs. Permeability is then calculated, provided that the fluid formation volume factor and viscosity are known. The accuracy of the calculated permeability is entirely dependent on the accuracy of the estimated formation thickness and the fluid properties.
4260buildup test, drawdown test, secondary recovery, tertiary recovery
4261None
4262kh
4263--
4264polyacrylate
42651.n. [Drilling Fluids]
4266Linear, anionic polymer made from the monomer acrylic acid, CH2=CHCOO- H+. The acrylic acid groups are evenly spaced along the chain. Acrylic acid polymer neutralized with NaOH is sodium polyacrylate (SPA). Polyacrylates are best utilized in soft water with low salinity to achieve the best dispersion and full chain elongation. Even low concentrations of hardness ions, for example, Ca+2, precipitate polyacrylates. Low molecular-weight polyacrylates are used as clay deflocculants. High molecular weight polymers are used for fluid-loss control and as a clay extender. As an extender, SPA is added to bentonite at the grinding plant. It is also used at the rig in low-solids mud. Divalent cations can negate its benefits as a clay extender. SPA is highly efficient when used to flocculate colloids in native-solids muds, clear-water muds and wastewater cleanup. The polymer chain links together colloidal solids that can be removed by gravity settling in shallow pits or by applying hydrocyclone, centrifuge or filtration techniques.
4267acrylamide polymer, acrylamide-acrylate polymer, anion, calcium contamination, clear-water drilling, deflocculant, deflocculated mud, flocculant, hardness ion, low-solids, nondispersed mud, native-solids mud, peptized clay, peptizing agent, PHPA mud, sodium bicarbonate, sodium carbonate, sodium polyacrylate, soft water, SPA, vinyl polymer, water clarification
4268acrylate polymer
4269None
4270--
4271pressure integrity test
42721.n. [Drilling]
4273Also known as leakoff test, a test to determine the strength or fracture pressure of the open formation, usually conducted immediately after drilling below a new casing shoe. During the test, the well is shut in and fluid is pumped into the wellbore to gradually increase the pressure that the formation experiences. At some pressure, fluid will enter the formation, or leak off, either moving through permeable paths in the rock or by creating a space by fracturing the rock. The results of the leakoff test dictate the maximum pressure or mud weight that may be applied to the well during drilling operations. To maintain a small safety factor to permit safe well control operations, the maximum operating pressure is usually slightly below the leakoff test result.
4274casing shoe, formation fracture pressure, fracture gradient, leakoff, mud weight
4275leakoff test
4276PIT
4277--
4278push down
42791.n. [Geophysics]
4280A phenomenon of relative seismic velocities of strata whereby a shallow layer or feature with a low seismic velocity (e.g., a shale diapir or a gas chimney) surrounded by rock with a higher seismic velocity causes what appears to be a structural low beneath it. After such features are converted from time to depth, the apparent structural low is generally reduced in magnitude. Hydrocarbon indicators can display velocity push-downs because the velocity of hydrocarbon is slower than that of rock.
4281depth conversion, hydrocarbon indicator, velocity, velocity anomaly
4282None
4283Antonyms:pull-up
4284--
4285permeable
42861.adj. [Geology]
4287Pertaining to arock's ability to transmit fluids. Permeability is typically measured in darcies or millidarcies. The term was defined by Henry Darcy, who showed that the common mathematics of heat transfer could be modified to adequately describefluid flowinporousmedia. Formations that transmit fluids readily, such as sandstones, are described as permeable and tend to have many large, well-connected pores. Impermeable formations, such as shales and siltstones, tend to be finer grained or of a mixed grain size, with smaller, fewer, or less interconnected pores. Absolute permeability is the measurement of the permeability conducted when a single fluid, or phase, is present in the rock. Effective permeability is the ability to preferentially flow or transmit a particular fluid through a rock when other immisciblefluids are present in the reservoir (for example, effective permeability of gas in a gas-water reservoir). The relative saturations of the fluids as well as the nature of the reservoir affect the effective permeability. Relative permeability is the ratio of effective permeability of a particular fluid at a particular saturation to absolute permeability of that fluid at total saturation. If a single fluid is present in a rock, its relative permeability is 1.0. Calculation of relative permeability allows for comparison of the different abilities of fluids to flow in the presence of each other, since the presence of more than one fluid generally inhibits flow.
4288absolute permeability, cap rock, effective permeability, fracture, fracture porosity, pore, pore pressure, porosity, relative permeability, reservoir, saturation, seal
4289None
4290Antonyms:impermeable
4291--
4292polyalphaolefin
42931.n. [Drilling Fluids]
4294One of the synthetic hydrocarbon liquids manufactured from the monomer ethylene, H2C=CH2. Polyalphaolefins have a complex branched structure with an olefin bond in the alpha position of one of the branches. Hydrogenated polyalphaolefins have olefin-carbons saturated with hydrogen, which lends excellent thermal stability to the molecule. Synthetic-base fluids (similar to oil muds) are made with the various types of synthetic liquids because the cuttings can be discharged in offshore waters, whereas discharge of cuttings coated with refined oils would be disallowed.
4295HSE, isomerized olefin, linear alphaolefin, olefinic hydrocarbon, oligomer, synthetic-base fluid
4296None
4297PAO
4298--
4299pressure sender
43001.n. [Well Workover and Intervention]
4301The sensor component in a system used to measure and display the pressure within a vessel or system. The pressure sender may be hydraulically or electrically connected to a remote gauge or display.
4302None
4303None
4304None
4305--
4306push down
43071.n. [Geophysics]
4308A phenomenon of relative seismic velocities of strata whereby a shallow layer or feature with a low seismic velocity (e.g., a shale diapir or a gas chimney) surrounded by rock with a higher seismic velocity causes what appears to be a structural low beneath it. After such features are converted from time to depth, the apparent structural low is generally reduced in magnitude. Hydrocarbon indicators can display velocity push-downs because the velocity of hydrocarbon is slower than that of rock.
4309depth conversion, hydrocarbon indicator, velocity, velocity anomaly
4310None
4311Antonyms:pull-up
4312--
4313perpendicular offset
43141.n. [Geophysics]
4315Generally, the distance between a receiver and a source in a survey, such as an electromagnetic survey. In seismic surveys, perpendicular or normal offset is the component of the distance between the source and geophones at a right angle to the spread.
4316electromagnetic method, offset, receiver, source, spread, survey
4317None
4318None
4319--
4320polyanionic cellulose
43211.n. [Drilling Fluids]
4322A cellulose derivative similar in structure, properties and usage in drilling fluids to carboxymethylcellulose. PAC is considered to be a premium product because it typically has a higher degree of carboxymethyl substitution and contains less residual NaCl than technical grade carboxymethylcellulose, although some PACs contain considerable NaCl.
4323calcium carbonate, carboxymethylcellulose, potassium mud
4324None
4325PAC
4326--
4327pressure squared plot
43281.n. [Well Testing]
4329A plot of p2 versus time function used to analyze low-pressure gas-well drawdown and buildup tests. The square term arises from substituting a gas-law equation into the differential equations where required to account for fluid compressibility. This allows an approximation for the differential equations that approaches the linear form required to use the classical solutions of the diffusion equation.
4330buildup test, diffusion equation, drawdown test, fluid compressibility
4331None
4332None
4333--
4334pusher
43351.n. [Drilling]
4336The location supervisor for the drilling contractor. The toolpusher is usually a senior, experienced individual who has worked his way up through the ranks of the drilling crew positions. His job is largely administrative, including ensuring that the rig has sufficient materials, spare parts and skilled personnel to continue efficient operations. The toolpusher also serves as a trusted advisor to many personnel on the rigsite, including the operator's representative, the company man.
4337company man, driller
4338drilling foreman, toolpusher
4339None
4340--
4341perpendicular resistivity
43421.n. [Formation Evaluation]
4343The resistivity of a formation measured by flowing current perpendicular to the bedding planes. In anisotropic formations, the parallel and perpendicular resistivities are different.
4344electrical anisotropy, horizontal resistivity, vertical resistivity
4345None
4346None
4347--
4348polycrystalline diamond compact bit
43491.n. [Drilling]
4350A drilling tool that uses polycrystalline diamond compact (PDC) cutters to shear rock with a continuous scraping motion. These cutters are synthetic diamond disks about 1/8-in. thick and about 1/2 to 1 in. in diameter. PDC bits are effective at drilling shale formations, especially when used in combination with oil-base muds.
4351bit
4352fixed-cutter bit, PDC bit
4353None
4354--
4355pressure storage tank
43561.n. [Production Facilities]
4357A tank designed for storing volatile liquids such as gasoline and liquefied petroleum gases (LPG), which generate high internal pressures. A pressure storage tank is commonly spherical. Other types include spheroidal or hemispherical vessels. Some pressure storage tanks can support several hundred pounds per square inch of internal pressure. A pressure storage tank is also called a pressure-type tank.
4358None
4359None
4360None
4361--
4362pyrolysis
43631.n. [Geology, Geochemistry, Shale Gas]
4364A type of geochemical analysis in which a rock sample is subject to controlled heating in an inert gas to or past the point of generating hydrocarbons in order to assess its quality as a source rock, the abundance of organic material in it, its thermal maturity, and the quality of hydrocarbons it might generate or have generated. Pyrolysis breaks large hydrocarbon molecules into smaller molecules.This process is used to determine the quality of shale as a source rock and is instrumental in evaluating shale gas plays.
4365generation, geochemistry, maturity, source rock
4366None
4367None
4368--
4369pyrolysis
43702.n. [General Terms]
4371Thermochemical breakdown of organic matter by heating in the absence of oxygen.
4372None
4373None
4374None
4375--
4376petal basket flowmeter
43771.n. [Production Logging]
4378A device for measuring in situ the velocity offluid flowin a production orinjection wellin which the flow is diverted through the spinner by a set of metal vanes, or petals. The vanes are closed while running in the hole, and then opened with the tool stationary at the measurement depth. The petals do not seal completely against each other or against the side of the hole, so that not all the fluid is diverted. A type of diverterflowmeter, the petal basket design has generally been replaced since the late 1980s by the inflatable diverter and other designs.
4379in situ, packer flowmeter, spinner flowmeter
4380basket flowmeter
4381None
4382--
4383polyglycerol
43841.n. [Drilling Fluids]
4385A series of alcohols with glycerol, C3H5(OH)3, (usually referred to as glycerin in the USA) being the simplest member. Polyglycerols have been used as shale inhibitors in water-base drilling fluids.
4386polyol
4387None
4388None
4389--
4390pressure transient analysis
43911.n. [Well Testing, Reservoir Characterization]
4392The analysis of pressure changes over time, especially those associated with small variations in the volume of fluid. In most well tests, a limited amount of fluid is allowed to flow from the formation being tested and the pressure at the formation monitored over time. Then, the well is closed and the pressure monitored while the fluid within the formation equilibrates. The analysis of these pressure changes can provide information on the size and shape of the formation as well as its ability to produce fluids.
4393None
4394None
4395None
4396--
4397pyrrhotite
43981.n. [Drilling Fluids]
4399A mineral containing ferrous sulfide, FeS, that typically contains inclusions of free sulfur and other minerals. It is commonly present in shales, and may occur as a trace mineral in some barite ores. Pyrrhotite can liberate sulfides in alkaline muds, with adverse consequences for safety and corrosion.Reference:Binder GG, Carlton LA and Garrett RL: "Evaluating Barite as a Source of Soluble Carbonate and Sulfide Contamination in Drilling Fluids," Journal of Petroleum Technology 33, no. 12 (December 1981): 2371-2376.
4400caustic extraction test, Garrett Gas Train, hydrogen sulfide, iron sulfide, siderite, sulfide, sulfide scavenger
4401None
4402None
4403--
4404petroleum
44051.n. [Geology]
4406A complex mixture of naturally occurring hydrocarbon compounds found in rock. Petroleum can range from solid to gas, but the term is generally used to refer to liquid crude oil. Impurities such as sulfur, oxygen and nitrogen are common in petroleum. There is considerable variation in color, gravity, odor, sulfur content and viscosity in petroleum from different areas.
4407bitumen, crude oil, geophysicist, hydrocarbon, hydrocarbon kitchen, maturity, methane, natural gas
4408None
4409None
4410--
4411polymer
44121.n. [Drilling Fluids]
4413A large molecule made up of repeating units. Some polymers are naturally occurring, such as xanthan gum, guar gum and starch. Other polymers are modified natural polymers, such as carboxymethylcellulose (CMC) and hydropropyl starch and lignosulfonate. Some are synthetic such as polyacrylates, polyacrylamides and polyalphaolefins. Polymers may be classified by their structure and may be linear, branched or less commonly cyclic. Copolymers contain two or more different monomers that can be arranged randomly or in blocks. In solution, entangled polymer chains can create networks, giving complex viscosity behavior. Polymers that ionize in solution are called polyelectrolytes. Charged groups strongly affect behavior and interactions with colloidal clays, other polymers and solvents. Molecular size (weight) influences how a specific polymer type performs in a given type of mud. A small polymer may be a deflocculant, whereas a large polymer of the same type may be a flocculant. Some are viscosifiers and others are fluid-loss control additives while others are multifunctional.
4414acrylamide polymer, acrylate polymer, biopolymer, carboxymethyl hydroxyethylcellulose, clay extender, colloid, conventional mud, copolymer, deflocculant, flocculant, gunk plug, hydrolysis, hydroxyethylcellulose, lignin, lignite, monomer, PHPA mud, polar compound, polyelectrolyte, polyol, resin, sodium bicarbonate, sodium carbonate, vinyl polymer, wastewater cleanup, water clarification, XC polymer
4415None
4416None
4417--
4418pressure transient test
44191.n. [Well Completions]
4420A means of assessing reservoir performance by measuring flow rates and pressures under a range of flowing conditions and applying the data to a mathematical model. Fundamental data relating to the interval under test, such as reservoir height and details of the reservoir fluids, are also input. The resulting outputs typically include an assessment of reservoir permeability, the flow capacity of the reservoir and any damage that may be restricting productivity.
4421None
4422None
4423None
4424--
4425q wave
44261.n. [Geophysics]
4427A type of surface wave in which particles oscillate horizontally and perpendicularly to the direction of wave propagation.
4428wave
4429Love wave
4430None
4431--
4432quartz
44331.n. [Geology]
4434[SiO2]An abundant rock-forming mineral composed of silicon and oxygen, also called silica. Quartz sand grains are a major constituent of sandstone and other clastic sedimentary rocks.
4435authigenic, chert, felsic, granite, hydrothermal, hydrothermal alteration, igneous, mineral, rock, sand, sandstone, sedimentary, silica, silicate mineral
4436None
4437None
4438--
4439quick look
44401.n. [Geophysics]
4441A subset of a 3D seismic survey comprising low fold or simplified processing (such as omitting dip moveout processing) that can be evaluated soon after acquisition.
4442acquisition, borehole seismic data, dip moveout, fold, processing, three-dimensional survey
4443None
4444None
4445--
4446quick look
44472.n. [Geophysics]
4448Borehole seismic data processed on site in the field
4449borehole seismic data
4450None
4451None
4452--
4453quick look
44543.n. [Formation Evaluation]
4455A log, or a display of several logs, that has been generated by a simple computation of log data. The quicklook is intended to make it easy to identify particular features in a section of log. The term is used for single curves designed, for example, to identify hydrocarbon zones, estimate porosity or identify lithology. Examples are Rwa, crossplot porosity, ratio method and apparent matrix density. The term is also used for a complete log containing some combination of quicklook curves, original logs and lithology display. In all cases the computations are based on simple models.
4456crossplot porosity
4457None
4458None
4459--
4460quitclaim
44611.vb. [Oil and Gas Business]
4462To convey whatever interests a grantor has at the time this particular instrument is executed. The grantor does this without warranty of title, either express or implied.
4463None
4464None
4465quitclaim
4466--
4467quitclaim
44682.n. [Oil and Gas Business]
4469A legal instrument of conveyance that is usually used in title curative work to allow an owner or claimant to quit or give up their claim to a title.
4470None
4471None
4472None
4473--
4474qa
44751.n. [Drilling Fluids]
4476Planned and systematic monitoring, testing and documenting of practices to show that a product or procedure meets established standards. Companies that manufacture, process, sell, handle, ship or buy drilling fluid materials typically establish QA programs. Some oil company labs perform QA testing. API and ISO jointly issue specifications for mud materials. A mud supplier must meet specifications and adhere to quality testing practices in order to place an API monogram (logo) on a product. Suppliers are required to pay for use of the API monogram program. Quality specifications that the API has adopted through joint user and supplier efforts are not always suitable for all users of the materials.
4477None
4478None
4479quality assurance
4480--
4481quebracho
44821.n. [Drilling Fluids]
4483A powdered form of tannic acid extract from the bark of the quebracho tree, used as a high-pH and lime mud deflocculant. It was in widespread use until the 1950s, at which time lignosulfonate became widely available and performed the same function better and cheaper than quebracho. High pH was needed to neutralize tannic acids to form the tannates, which are red. The oilfield name red mud was applied to tannate-dispersed muds.
4484None
4485None
4486None
4487--
4488quicklook
44891.n. [Geophysics]
4490A subset of a 3D seismic survey comprising low fold or simplified processing (such as omitting dip moveout processing) that can be evaluated soon after acquisition.
4491acquisition, borehole seismic data, dip moveout, fold, processing, three-dimensional survey
4492None
4493None
4494--
4495quicklook
44962.n. [Geophysics]
4497Borehole seismic data processed on site in the field
4498borehole seismic data
4499None
4500None
4501--
4502quicklook
45033.n. [Formation Evaluation]
4504A log, or a display of several logs, that has been generated by a simple computation of log data. The quicklook is intended to make it easy to identify particular features in a section of log. The term is used for single curves designed, for example, to identify hydrocarbon zones, estimate porosity or identify lithology. Examples are Rwa, crossplot porosity, ratio method and apparent matrix density. The term is also used for a complete log containing some combination of quicklook curves, original logs and lithology display. In all cases the computations are based on simple models.
4505crossplot porosity
4506None
4507None
4508--
4509q wave
45101.n. [Geophysics]
4511A type of surface wave in which particles oscillate horizontally and perpendicularly to the direction of wave propagation.
4512wave
4513Love wave
4514None
4515--
4516quality assurance
45171.n. [Drilling Fluids]
4518Planned and systematic monitoring, testing and documenting of practices to show that a product or procedure meets established standards. Companies that manufacture, process, sell, handle, ship or buy drilling fluid materials typically establish QA programs. Some oil company labs perform QA testing. API and ISO jointly issue specifications for mud materials. A mud supplier must meet specifications and adhere to quality testing practices in order to place an API monogram (logo) on a product. Suppliers are required to pay for use of the API monogram program. Quality specifications that the API has adopted through joint user and supplier efforts are not always suitable for all users of the materials.
4519caustic extraction test
4520None
4521QA
4522--
4523quick lime
45241.n. [Drilling Fluids]
4525A chemical with formula CaO, commonly called quick lime or hot lime. When hydrated with one mole of water, it forms slaked lime, Ca(OH)2. Quick lime is used in preference to slaked lime at oil mud mixing plants because it generates heat when it becomes slaked with water and therefore speeds up emulsification by the reaction to form calcium fatty-acid soap.
4526calcium hydroxide, slaked lime
4527None
4528None
4529--
4530rabbit
45311.n. [Well Completions]
4532A slang term for an internal drift diameter gauge typically used to check casing or tubing joints before they are picked up and run into the wellbore. The drift diameter used depends on the size and weight of the tubular being checked.
4533drift
4534None
4535None
4536--
4537recovery factor
45381.n. [Enhanced Oil Recovery]
4539The recoverable amount of hydrocarbon initially in place, normally expressed as a percentage. The recovery factor is a function of the displacement mechanism. An important objective of enhanced oil recovery is to increase the recovery factor.
4540None
4541None
4542None
4543--
4544reservoir simulation
45451.n. [Reservoir Characterization]
4546A computer run of a reservoir model over time to examine the flow of fluid within the reservoir and from the reservoir. Reservoir simulators are built on reservoir models that include the petrophysical characteristics required to understand the behavior of the fluids over time. Usually, the simulator is calibrated using historic pressure and production data in a process referred to as "history matching." Once the simulator has been successfully calibrated, it is used to predict future reservoir production under a series of potential scenarios, such as drilling new wells, injecting various fluids or stimulation.
4547None
4548None
4549None
4550--
4551rih
45521.vb. [Drilling]
4553To connect pipe together and lower the connected length into the borehole in a controlled fashion. The pipe lengths are usually screwed together either with rotary-shouldered connections for the drillstring, or threaded and coupled connections for casing, liners and most tubing.
4554None
4555None
4556Antonyms:come out of the hole
4557--
4558racking back pipe
45591.vb. [Drilling]
4560To place a stand of drillpipe in the derrick when coming out of the hole on a trip. The rig crew racks back pipe after the stand is unscrewed from the rest of the drillstring. The floor crew then pushes the lower part of the stand away from the rotary table to a position on one side of the vee-door. While the floor crew is pushing the pipe, the derrickman gets ready to pull the top of the stand over into the fingerboards. Once the rig crew has the pipe in the correct location, the driller slacks off on the drawworks, allowing the stand to rest on the drillfloor. This takes weight off of the elevators previously supporting the pipe at the top, so the derrickman can then unlatch the elevators and pull the top of the pipe into the fingerboards for storage. Modern rig designs have automated pipe-handling equipment that moves the pipe. When tripping the pipe out of the hole, racking back pipe may occur every two to five minutes for hours at a time.
4561come out of the hole, derrickman, elevator, fingerboard, rotary table, stand, vee-door
4562None
4563None
4564--
4565recovery forecast
45661.n. [Reservoir Characterization]
4567A prediction of the amount of production that will occur from a well, reservoir or field. This estimate is sometimes expressed as a fraction of the total hydrocarbons originally in place
4568None
4569None
4570None
4571--
4572reservoir drive mechanisms
45731.n. [Enhanced Oil Recovery, Production Testing]
4574Natural forces in the reservoir that displace hydrocarbons out of the reservoir into the wellbore and up to surface.Reservoir-drive mechanisms include gasdrive (gas cap or solution gasdrive), waterdrive (bottomwater drive or edgewater drive), combination drive, and gravity drainage. Waterdrive is the most efficient drive mechanism, followed by gasdrive and gravity drainage.Reservoir-drive mechanisms are also called natural drives.
4575primary recovery
4576None
4577None
4578--
4579ring resistivity
45801.n. [Formation Evaluation]
4581The resistivity measured by the ring of a measurements-while-drilling (MWD) toroid device. The ring resistivity is a focused measurement with a depth of investigation and a vertical resolution of a few inches. It is not azimuthal. The measurement is similar to a wireline laterolog except that toroids are used instead of electrodes for transmitting and monitoring. Like a laterolog, the signal is proportional to resistivity, and is thus most effective at high resistivities, high formation to mud-resistivity contrast and in the presence of conductive invasion. It is usually combined with the bit resistivity, and possibly also with the button resistivities.In the same way as a laterolog, two transmitter toroids are used to force current to flow approximately perpendicularly into the formation at the ring. Other toroids measure the current flow and to balance the currents emitted by the two transmitters.
4582electrode resistivity
4583None
4584None
4585--
4586radial array
45871.n. [Geophysics]
4588An array of sources or receivers radiating outward from a central point, usually a borehole.
4589array
4590None
4591None
4592--
4593red mud
45941.n. [Drilling Fluids]
4595A clay-based water mud that used tannates (from tannic acid) as clay deflocculant and mined lignite for fluid-loss control, usually with lime. The tannates were usually quebracho, which is red at high pH. Red muds were used extensively in the 1940s and 1950s.
4596deflocculant, lime mud, pH, starch, tannin
4597None
4598quebracho
4599--
4600residence time
46011.n. [Production Facilities]
4602Another term for retention time, the amount of time a liquid stays in a vessel. The retention time assures that equilibrium between the liquid and gas has been reached at separator pressure. The retention time in a separator is determined by dividing the liquid volume inside the vessel by the liquid flow rate. The retention time usually varies between 30 seconds and 3 minutes. If a foaming crude is present, the retention time could be increased by four times its normal values.
4603None
4604retention time
4605None
4606--
4607ringworm corrosion
46081.n. [Enhanced Oil Recovery]
4609A type of bimetallic corrosion. Ringworm corrosion has the shape of a ring and is located a few inches from the pipe upset. The ring can either be very smooth or have severe pitting.Ringworm corrosion is caused by the upsetting process, in which the heat required for upsetting creates two different grain structures, one in the upset and another in the rest of the pipe. This condition can be avoided by fully normalizing the pipe after upsetting. To normalize the pipe, heat is applied to change the grains to a uniform structure.
4610corrosion control
4611None
4612None
4613--
4614radial differential temperature log
46151.n. [Production Logging]
4616A record of the difference in temperature between the opposite sides of the internal wall of a casing. The log is mainly used to detect a channel in the cement, since the fluid moving in the channel is likely to be cooler or warmer than its surroundings. The two temperature probes are held on arms that are extended to touch the casing wall at depths where a channel is suspected. The assembly is then rotated through 360o to give the radial differential-temperature log. A sinusoid indicates a channel. Temperature differences are small, typically 0.005 to 0.05oF [0.003 to 0.03oC], but can be enhanced by injecting cooler fluids from surface.
4617differential temperature log, production log
4618None
4619None
4620--
4621reef
46221.n. [Geology]
4623A mound, ridge, or buildup of sediment or sedimentary rock, most commonly produced by organisms that secrete shells such as corals. Reefs are typically taller than the sediment that surrounds them, resistant to weathering and wave action, and preserved within sediment of a different composition. Carbonate reefs form in a limited range of temperatures, water depths, salinities and wave activities, so their occurrence can be used to interpret past environmental conditions. Because the rocks that surround reefs can differ in composition and permeability, porous reefs can form stratigraphic traps for hydrocarbons. Porosity of reefal limestones depends on post-depositional diagenetic changes.
4624carbonate, carbonate, depositional environment, diagenesis, differential compaction, drape, limestone, permeability, porosity, sediment, sedimentary, stratigraphic trap, weathering
4625None
4626None
4627--
4628residual bend
46291.n. [Well Workover and Intervention]
4630The natural form that a section of coiled tubing string will take if spooled from the reel and allowed to rest without any tension applied. The residual bend results from the plastic deformation imparted as the string is spooled around the radius of the reel and guide arch.
4631None
4632None
4633None
4634--
4635road box
46361.n. [Production]
4637A concrete or metal box with a removable cover, enclosing and providing access to valves installed in buried lines alongside roads or streets. The valves are operated by removing the box cover and inserting a long-handled T-wrench which engages the valve stem or the pinion shaft of geared valves.
4638None
4639None
4640None
4641--
4642radial differential temperature log
46431.n. [Production Logging]
4644A record of the difference in temperature between the opposite sides of the internal wall of a casing. The log is mainly used to detect a channel in the cement, since the fluid moving in the channel is likely to be cooler or warmer than its surroundings. The two temperature probes are held on arms that are extended to touch the casing wall at depths where a channel is suspected. The assembly is then rotated through 360o to give the radial differential-temperature log. A sinusoid indicates a channel. Temperature differences are small, typically 0.005 to 0.05oF [0.003 to 0.03oC], but can be enhanced by injecting cooler fluids from surface.
4645differential-temperature log, production log
4646None
4647None
4648--
4649reefal
46501.adj. [Geology]
4651Pertaining to reef, a mound, ridge, or buildup of sediment or sedimentary rock, most commonly produced by organisms that secrete shells such as corals. Reefs are typically taller than the sediment that surrounds them, resistant to weathering and wave action, and preserved within sediment of a different composition. Carbonate reefs form in a limited range of temperatures, water depths, salinities and wave activities, so their occurrence can be used to interpret past environmental conditions. Because the rocks that surround reefs can differ in composition and permeability, porous reefs can form stratigraphic traps for hydrocarbons. Porosity of reefal limestones depends on post-depositional diagenetic changes.
4652carbonate, depositional environment, diagenesis, differential compaction, drape, limestone, permeability, porosity, sediment, sedimentary, stratigraphic trap, weathering
4653None
4654None
4655--
4656resin
46571.n. [Drilling Fluids]
4658Organic material having low solubility. Resins are usually large and complex polymeric molecules with noncrystalline structure and no distinct melting point or other definitive properties. Resins are used as additives to improve filter cake, provide lubricity or stop lost circulation as lost-circulation material. Resins are derived from plant sources (such as pine trees), some are residues of manufacturing processes and some resins are mined material.
4659bridging material, filter cake, gilsonite, hardness ion, ion exchange, lubricant, polymer
4660None
4661None
4662--
4663resin
46642.n. [Heavy Oil]
4665One of the four main components of petroleum, along with asphaltenes, aromatics and saturates (which include waxes). Resins, aromatics and saturates are also known as maltenes. Resin adds to the stickiness and viscosity of heavy oil.
4666None
4667None
4668None
4669--
4670rock
46711.n. [Geology]
4672An aggregate of minerals or organic matter (in the case of coal, which is not composed of minerals because of its organic origin), or volcanic glass (obsidian, which forms a rock but is not considered a mineral because of its amorphous, noncrystalline nature). Rocks can contain a single mineral, such as rock salt (halite) and certain limestones (calcite), or many minerals, such as granite (quartz, feldspar, mica and other minerals). There are three main types of rocks. Sedimentary rocks like sandstone and limestone form at the Earth's surface through deposition of sediments derived from weathered rocks, biogenic activity or precipitation from solution. Igneous rocks originate deeper within the Earth, where the temperature is high enough to melt rocks, to form magma that can crystallize within the Earth or at the surface by volcanic activity. Metamorphic rocks form from other preexisting rocks during episodes of deformation of the Earth at temperatures and pressures high enough to alter minerals but inadequate to melt them. Such changes can occur by the activity of fluids in the Earth and movement of igneous bodies or regional tectonic activity. Rocks are recycled from one type to another by the constant changes in the Earth.
4673arenaceous, argillaceous, granite, groundwater, mineral, plate tectonics, stratum, weathering
4674None
4675None
4676--
4677radial faulting
46781.n. [Geology]
4679Multiple faults whose fault planes strike outward from a common center. Such faults typically are associated with salt domes, impact craters or volcanoes.
4680dome, salt dome, volcano
4681None
4682None
4683--
4684reel
46851.n. [Well Workover and Intervention]
4686The device used to store and transport a coiled tubing string ready for use at the wellsite. The coiled tubing reel incorporates a manifold and swivel arrangement to enable fluids to be pumped through the coiled tubing string at any time, a levelwind assembly to ensure the string is correctly spooled and a treatment system to apply inhibitor or similar protective coatings to the coiled tubing string. The reel functions are hydraulically powered and controlled from the unit control cabin.
4687None
4688None
4689None
4690--
4691resistive invasion
46921.n. [Formation Evaluation]
4693A situation in which the resistivity of the flushed zone is greater than the resistivity of the undisturbed zone. Such a setting generally favors the use of induction devices, which respond to conductivity, rather than electrode resistivity devices (laterologs, ring resistivity), which respond to resistivity.
4694true resistivity, undisturbed zone
4695None
4696Antonyms:conductive invasion
4697--
4698rock properties
46991.n. [Reservoir Characterization]
4700The physical characteristics of reservoir rocks that enable them to store fluids and to allow fluids to flow through them. The main properties of interest are rock porosities and permeabilities.
4701None
4702None
4703None
4704--
4705radial processing
47061.n. [Formation Evaluation]
4707The inversion of resistivity logs with differing depths of investigation into a model of the formation invasion profile. For dual induction and dual-laterolog tools, this was done graphically with a tornado chart and assuming a step profile. Array tools have built-in inversion algorithms, and several formation models into which the data can be inverted.
4708array induction
4709None
4710None
4711--
4712reeled tubing
47131.n. [Drilling]
4714Another term for coiled tubing, a long, continuous length of pipe wound on a spool. The pipe is straightened prior to pushing into a wellbore and rewound to coil the pipe back onto the transport and storage spool. Depending on the pipe diameter (1 in. to 4 1/2 in.) and the spool size, coiled tubing can range from 2,000 ft to 15,000 ft [610 to 4,570 m] or greater length.
4715coiled tubing drilling, endless tubing, packer
4716coiled tubing, CT
4717None
4718--
4719reeled tubing
47202.n. [Well Workover and Intervention]
4721A generic term relating to the use of a coiled tubing string and associated equipment. As a well-intervention method, coiled tubing techniques offer several key benefits over alternative well-intervention technologies. The ability to work safely under live well conditions, with a continuous string, enables fluids to be pumped at any time regardless of the position or direction of travel. This is a significant advantage in many applications. Installing an electrical conductor or hydraulic conduit further enhances the capability of a coiled tubing string and enables relatively complex intervention techniques to be applied safely.
4722None
4723coiled tubing, CT, endless tubing
4724None
4725--
4726resistivity log
47271.n. [Formation Evaluation]
4728A log of the resistivity of the formation, expressed in ohm-m. The resistivity can take a wide range of values, and, therefore, for convenience is usually presented on a logarithmic scale from, for example, 0.2 to 2000 ohm-m. The resistivity log is fundamental in formation evaluation because hydrocarbons do not conduct electricity while all formation waters do. Therefore a large difference exists between the resistivity of rocks filled with hydrocarbons and those filled with formation water. Clay minerals and a few other minerals, such as pyrite, also conduct electricity, and reduce the difference. Some measurement devices, such as induction and propagation resistivity logs, may respond more directly to conductivity, but are presented in resistivity.
4729bit resistivity, dielectric propagation log, electrical log, electromagnetic propagation, fresh water, ring resistivity, saturation equation
4730None
4731None
4732--
4733resistivity log
47342.n. [Formation Evaluation]
4735A log of the resistivity of the formation made by an electrode device such as a laterolog. In this sense the term is used to distinguish the log from an induction measurement, which responds more directly to conductivity.
4736electrode resistivity
4737None
4738None
4739--
4740rock types
47411.n. [Reservoir Characterization]
4742A set of characteristics that several rocks have in common. The characteristics of interest are usually those pertaining to fluid movement and fluid storage capacity.
4743None
4744None
4745None
4746--
4747radial refraction
47481.n. [Geophysics]
4749A surveying technique used to identify local, high-velocity features such as salt domes, also called fan shooting.
4750salt dome
4751None
4752None
4753--
4754radial refraction
47552.n. [Geophysics]
4756A borehole seismic method in which a surface source transmits seismic energy from various locations to a receiver in a wellbore to locate high-velocity features such as salt domes.
4757borehole seismic data, receiver, salt proximity survey, source
4758None
4759None
4760--
4761reference point
47621.n. [Formation Evaluation]
4763The position on a logging tool string that is used as the reference for depth measurements. Each measurement has a different measure point. In normal practice, each measurement is shifted in depth by the distance between the measure point and the reference point. This ensures that all measurements are recorded at the same depth. For a wireline tool, the reference point is normally the bottom of the tool string. For measurements-while-drilling, the reference is the bit (the driller's depth). The term is sometimes used to mean the depth reference.
4764depth wheel, first reading, pick-up
4765None
4766None
4767--
4768resolution matched
47691.adj. [Formation Evaluation]
4770Relating to two or more logging measurements that have the same resolution. The term normally refers to vertical resolution, but could also be used for azimuthal or radial resolution.
4771response matched, vertical response
4772None
4773None
4774--
4775Rockwell hardness testing
47761.n. [Production]
4777Rockwell hardness testing is a testing method that uses a conical diamond or a steel ball to indent the surface of metals or polymers. The hardness number is determined from the depth of deformation created by the indenter into the sample.
4778None
4779None
4780None
4781--
4782radial resolution
47831.n. [Formation Evaluation]
4784A distance that characterizes the ability of a logging measurement to resolve changes in the formation perpendicular to the tool. Alternatively, the term refers to the smallest distance for which a significant change can be detected. The resolution is a feature of the radial response, which is often summarized by a geometrical or pseudogeometrical factor. A measurement with good or high radial resolution will have a sharp peak in the radial differential geometric factor at some distance from the tool.
4785radius of investigation
4786None
4787None
4788--
4789reflection
47901.n. [Geophysics]
4791Generally, the return or rebound of particles or energy from the interface between two media. There are two laws of reflection, which state (1) that incident rays, reflected rays and the normal to the reflecting interface at the point of incidence are coplanar, and (2) that the angle of incidence is equal to the angle of reflection. In geophysics, reflection refers to the seismic energy or signal that returns from an interface of contrasting acoustic impedance, known as a reflector, according to Snell's law. Reflection seismic surveys are useful for mapping geologic structures in the subsurface, interpreting sedimentary environments and evaluating hydrocarbon accumulations that might occur as amplitude anomalies. Reflection surveys are complicated by the variation of velocity as well as the various types of wave energy that are propagated within the Earth. In electromagnetics, variation in electrical properties produces reflections.
4792acoustic transparency, amplitude anomaly, arrival, attenuation, autotrack, complex-trace analysis, converted wave, critical reflection, deep seismic sounding, diffraction, drill-noise vertical seismic profile, electromagnetic method, Fermat's principle, footprint, primary reflection, raypath, reflection coefficient, reflector, refraction, seismic-while-drilling vertical seismic profile, Snell's law
4793None
4794None
4795--
4796response matched
47971.adj. [Formation Evaluation]
4798Relating to two or more logging measurements that have the same response. The term normally refers to vertical resolution, but could also be used for azimuthal or radial resolution. The term implies that all the features of the vertical response are matched, ideally in all conditions. In practice, it is used to describe a more detailed matching of the vertical response than with resolution-matched curves.
4799vertical resolution
4800None
4801None
4802--
4803rod elevators
48041.n. [Well Workover and Intervention]
4805Lightweight elevators designed for running and retrieving the sucker-rod string in wells equipped with a rod pump. Rod elevators can be used on a workover rig or a rod unit specifically designed for running and retrieving rod strings.
4806elevator, rod unit
4807None
4808None
4809--
4810radial response
48111.n. [Formation Evaluation]
4812The response of a logging measurement as a function of the distance perpendicular to the tool. Radial responses are determined by computer simulation or laboratory measurement. For some measurements, mainly resistivity, the radial response can be shaped as desired through signal processing. In general, the radial response depends on the formation properties throughout the measurement volume. Most quoted radial responses have been determined in formations that are vertically homogeneous and have small radial changes. They can then be summarized by a geometrical factor or a pseudogeometrical factor. These factors are appropriate for volumetric measurements such as nuclear and resistivity measurements, but not for others such as acoustic propagation.
4813depth of investigation, radial resolution, vertical response
4814None
4815None
4816--
4817refraction
48181.n. [Geophysics]
4819The change in the direction of travel of awavefront, or the bending of a ray, as it passes from one medium to another, expressed mathematically by Snell's law. Refraction is a consequence of changes inwavelengthandvelocityof propagation of awaveproduced by differences in refractive indices of the media. Refraction surveys where the incident and reflected angles are critical can be useful for evaluating increasing velocity gradients and locating features that have anomalously high velocities, such as asalt domewithin surrounding rocks of lower velocities.
4820angle of approach, angle of incidence, blind zone, converted wave, critical angle, deep seismic sounding, displacement, Fermat's principle, head wave, reflection, refractive index, Snell's law, weathering correction
4821seismic refraction method
4822None
4823--
4824retarder
48251.n. [Well Completions]
4826A chemical additive used to increase the thickening time of cement slurries or similar fluids that may have a limited pumping time. The increased pressure and temperature typically associated with deep wellbores requires the use of such performance-enhancing additives to enable efficient placement without premature setting.
4827None
4828None
4829None
4830--
4831rod unit
48321.n. [Well Workover and Intervention]
4833A lightweight workover unit specifically designed for running and retrieving rod strings and rod pumps. Rod units are generally truck-mounted and configured to suit the relatively light work associated with rod-pump servicing.
4834None
4835None
4836None
4837--
4838radio safe detonator
48391.n. [Perforating]
4840Electric detonators used in wireline and electronic firing-head perforating operations, which are immune to radio interference and thus cannot be accidentally triggered by radio transmissions.
4841None
4842None
4843None
4844--
4845refractor
48461.n. [Geophysics]
4847A layer of rock that is sufficiently thick, areally extensive, and has a distinctly higher velocity than the rocks immediately above it such that it can transmit a head wave, or a wave transmitted at its critical incident angle.
4848angle of incidence, critical angle, velocity, wave
4849None
4850None
4851--
4852retention time
48531.n. [Production Facilities]
4854The amount of time a liquid stays in a vessel. The retention time assures that equilibrium between the liquid and gas has been reached at separator pressure. The retention time in a separator is determined by dividing the liquid volume inside the vessel by the liquid flow rate. The retention time usually varies between 30 seconds and 3 minutes. If a foaming crude is present, the retention time could be increased by four times its normal values.
4855None
4856residence time
4857None
4858--
4859roller cone bit
48601.n. [Drilling]
4861A tool designed to crush rock efficiently while incurring a minimal amount of wear on the cutting surfaces. Invented by Howard Hughes, the roller-cone bit has conical cutters or cones that have spiked teeth around them. As the drillstring is rotated, the bit cones roll along the bottom of the hole in a circle. As they roll, new teeth come in contact with the bottom of the hole, crushing the rock immediately below and around the bit tooth. As the cone rolls, the tooth then lifts off the bottom of the hole and a high-velocity fluid jet strikes the crushed rock chips to remove them from the bottom of the hole and up the annulus. As this occurs, another tooth makes contact with the bottom of the hole and creates new rock chips. Thus, the process of chipping the rock and removing the small rock chips with the fluid jets is continuous. The teeth intermesh on the cones, which helps clean the cones and enables larger teeth to be used. There are two main types of roller-cone bits, steel milled-tooth bits and carbide insert bits.
4862None
4863None
4864roller-cone bit
4865--
4866radio silence
48671.n. [Perforating]
4868A procedure imposed during perforating operations in which radios at or near the wellsite are switched off to prevent accidental detonation of perforating guns. Radio silence is required for wireline operations when using a non-radio-safe detonator. It is typically imposed when rigging up perforating guns and until the guns have been run in the hole to 200 ft [61 m] below ground level or mud line. Radio silence is imposed again when retrieving the gun system as it passes the 200-ft mark. Radio silence must be maintained until it has been confirmed that all charges have been shot. This practice is not required when radio-safe detonators are used, but is common practice at many wellsites.
4869None
4870None
4871None
4872--
4873refracturing
48741.n. [Shale Gas]
4875An operation to restimulate a well after an initial period of production. Refracturing operations attempt to bypass near-wellbore damage, reestablish good connectivity with the reservoir, and tap portions of the reservoir with higher pore pressure. Refracturing operations are also performed after a period of production that can alter the stresses in a reservoir due to depletion; the restimulation can allow the new fracture to reorient along a different azimuth. A successful refracturing operation restores well productivity to near original or even higher rates of production and extends the productive life of a well.
4876None
4877None
4878None
4879--
4880retort solids
48811.n. [Drilling Fluids]
4882The volume percent (or fraction) of a mud that is not captured in the receiver when performing the water, oil and solids test as prescribed by API, as given in the equation below.Retort solids thus include suspended solids, dissolved solids (salts), charred organic materials and volatile materials that do not condense. For calculations, retort solids are normally assumed to be only suspended and dissolved solids, as in the equation below.Volume percent suspended solids (weighting material plus drill solids) is of particular interest to mud engineers. To calculate that percentage, the volume increase caused by the dissolved salts is determined from filtrate analyses of chloride and calcium ions. For oil muds, the calculations are more complicated.
4883calcium test, chloride test, dissolved solids, drill solids, high-gravity solids, material-balance equation, retort, suspended solids, water, oil and solids test
4884None
4885None
4886--
4887roller cone bit
48881.n. [Drilling]
4889A tool designed to crush rock efficiently while incurring a minimal amount of wear on the cutting surfaces. Invented by Howard Hughes, the roller-cone bit has conical cutters or cones that have spiked teeth around them. As the drillstring is rotated, the bit cones roll along the bottom of the hole in a circle. As they roll, new teeth come in contact with the bottom of the hole, crushing the rock immediately below and around the bit tooth. As the cone rolls, the tooth then lifts off the bottom of the hole and a high-velocity fluid jet strikes the crushed rock chips to remove them from the bottom of the hole and up the annulus. As this occurs, another tooth makes contact with the bottom of the hole and creates new rock chips. Thus, the process of chipping the rock and removing the small rock chips with the fluid jets is continuous. The teeth intermesh on the cones, which helps clean the cones and enables larger teeth to be used. There are two main types of roller-cone bits, steel milled-tooth bits and carbide insert bits.
4890antiwhirl bit, bit, crushed zone
4891None
4892None
4893--
4894radioactive tracer
48951.n. [Production Testing]
4896A component of a production-logging tool that carries a radioactive solution (often carnotite) that can be selectively released into a flow stream. When the radioactive solution is released into an injected fluid, the movement of the mixture can be traced by gamma ray detectors located in the tool.Radioactive tracers are generally used in injection wells rather than in production wells to avoid radioactive contamination at the surface. The main applications of radioactive tracers include establishing flow profiles in injection wells, detecting fluid movements behind the pipe, and locating leaking packers and fluid movement between wells.
4897injection well
4898None
4899None
4900--
4901regression
49021.n. [Geology]
4903The migration of shoreline into a basin during progradation due to a fall in relative sea level. Deposition during a regression can juxtapose shallow-water sediments atop deep-water sediments.
4904basin, condensed section, eustasy, progradation, sequence stratigraphy, systems tract
4905None
4906Antonyms:transgression
4907--
4908regression
49092.n. [Reservoir Characterization]
4910The statistical fitting of trend lines to a data set. Many regression methods are available, including linear, iterative, multiple and polynomial. If there is a 'good' fit to the data, then the variables are often assumed to be dependent.
4911None
4912None
4913None
4914--
4915retort test
49161.n. [Enhanced Oil Recovery]
4917A test for water mud oroil mud, also known as the water, oil and solids test.Proper procedures for retort tests have been published by API. The test is a distillation of a mud sample that measures condensed oil and water collected from the retort. Data obtained are: (1) vol. % water, (2) vol. % oil and (3) vol. % retort solids. Retort solids is the volume that was not recovered as a liquid. Three sizes of retort apparatus are available: 10-, 20- and 50-cm3 mud sample size. Some designs have a small oven in the carrying case to heat the sample (the preferred method for oil muds) while others use a blade heater that goes into the mud sample. Retorts should be heated to around 700°F [371°C] to be effective.
4918dissolved solids, total solids
4919water, oil and solids test
4920None
4921--
4922rolling aging test
49231.n. [Drilling Fluids]
4924A mud test in which the mud sample is mildly agitated by rolling (or tumbling) for the duration of the test, usually performed at a selected high temperature. Typically, the mud sample is sealed in a mud-aging cell and placed in an oven that will roll (or tumble) the mud cells continually for a given period of time (often 16 hours or overnight). The cooled mud is tested for properties. A rolled (or tumbled) mud sample simulates circulation in the hole by pumping.
4925None
4926None
4927rolling-aging test
4928--
4929radio safe detonator
49301.n. [Perforating]
4931Electric detonators used in wireline and electronic firing-head perforating operations, which are immune to radio interference and thus cannot be accidentally triggered by radio transmissions.
4932None
4933None
4934None
4935--
4936regressive
49371.adj. [Geology]
4938Pertaining to regression, the migration of shoreline into a basin during progradation due to a fall in relative sea level. Deposition during a regression can juxtapose shallow-water sediments atop deep-water sediments.
4939basin, condensed section, eustasy, progradation, sequence stratigraphy, systems tract
4940None
4941Antonyms:transgressive
4942--
4943regressive
49442.adj. [Reservoir Characterization]
4945Pertaining to regression, the statistical fitting of trend lines to a data set. Many regression methods are available, including linear, iterative, multiple and polynomial. If there is a 'good' fit to the data, then the variables are often assumed to be dependent.
4946None
4947None
4948None
4949--
4950retrievable gun
49511.n. [Perforating]
4952A perforating gun designed to be retrieved from the wellbore after firing. Retrievable guns are generally configured for minimal debris and distortion of the gun body to help ensure easy retrieval.
4953None
4954None
4955Antonyms:expendable gun
4956--
4957rolling aging test
49581.n. [Drilling Fluids]
4959A mud test in which the mud sample is mildly agitated by rolling (or tumbling) for the duration of the test, usually performed at a selected high temperature. Typically, the mud sample is sealed in a mud-aging cell and placed in an oven that will roll (or tumble) the mud cells continually for a given period of time (often 16 hours or overnight). The cooled mud is tested for properties. A rolled (or tumbled) mud sample simulates circulation in the hole by pumping.
4960barrel equivalent, mud oven, mud-aging cell, pilot test, static-aging test, temperature stability
4961dynamic-aging test
4962None
4963--
4964radius of investigation
49651.n. [Formation Evaluation]
4966A distance that characterizes how far a logging tool measures into the formation from the axis of the tool or borehole. The term is similar to depth of investigation, but is more appropriate for certain azimuthally symmetric measurements, mainly resistivity.The radius of investigation summarizes the radial response of the measurement in one or more distances, and should be associated with the percentage of signal received from within that depth, typically either 50% or 90%. Most quoted depths of investigation assume a homogeneous formation with certain properties, such as a given resistivity or fluid content. The radius of investigation can vary considerably in inhomogeneous conditions, and at different values of the properties concerned. It should be considered only a qualitative guide to tool response.
4967radial response
4968None
4969None
4970--
4971radius of investigation
49722.n. [Well Testing]
4973The calculated maximum radius in a formation in which pressure has been affected during the flow period of a transient well test. While not absolutely accurate, the value has meaning in relation to the total volume of reservoir that is represented by calculated reservoir parameters, such as kh, the permeability thickness. This may also be termed transient drainage radius.
4974permeability thickness
4975transient drainage radius
4976None
4977--
4978relative age
49791.n. [Geology]
4980The approximate age determination of rocks, fossils or minerals made by comparing whether the material is younger or older than other surrounding material. Relative age is estimated according to stratigraphic and structural relationships, such as superposition, and by fossil content, since the relative ages and successions of fossils have been established by paleontologists. The measurement of the decay of radioactive isotopes, especially uranium, rubidium, argon and carbon, has allowed geologists to more precisely determine the age in years of rock formations, known as the absolute age. Tree rings and seasonal sedimentary deposits called varves can be counted to determine absolute age. Although the term implies otherwise, "absolute" ages typically have some amount of potential error and are inexact.
4981absolute age, chronostratigraphy, formation, geochronology, geologic time scale, lithologic contact, paleontology, plankton, stratigraphy, superposition, varve
4982None
4983None
4984--
4985retrogradation
49861.n. [Geology]
4987The accumulation of sequences by deposition in which beds are deposited successively landward because sediment supply is limited and cannot fill the available accommodation. Thus, the position of the shoreline migrates backward onto land, a process called transgression, during episodes of retrogradation.
4988accommodation, bed, onlap, sequence, sequence stratigraphy, transgression
4989None
4990Antonyms:progradation
4991--
4992root mean square velocity
49931.n. [Geophysics]
4994The value of the square root of the sum of the squares of the velocity values divided by the number of values, symbolized by vrms. The root-mean-square velocity is that of a wave through subsurface layers of different interval velocity along a specific raypath, and is typically several percent higher than the average velocity. The stacking velocity and the root-mean-square velocity approach equality when source-receiver offset approaches zero and layers are horizontal and isotropic.
4995Dix formula, raypath, stacking velocity, velocity
4996None
4997None
4998--
4999ram blowout preventer
50001.n. [Drilling]
5001A device that can be used to quickly seal the top of the well in the event of a well control event (kick). A ram blowout preventer (BOP) consists of two halves of a cover for the well that are split down the middle. Large-diameter hydraulic cylinders, normally retracted, force the two halves of the cover together in the middle to seal the wellbore. These covers are constructed of steel for strength and fitted with elastomer components on the sealing surfaces. The halves of the covers, formally called ram blocks, are available in a variety of configurations. In some designs, they are flat at the mating surfaces to enable them to seal over an open wellbore. Other designs have a circular cutout in the middle that corresponds to the diameter of the pipe in the hole to seal the well when pipe is in the hole. These pipe rams effectively seal a limited range of pipe diameters. Variable-bore rams are designed to seal a wider range of pipe diameters, albeit at a sacrifice of other design criteria, notably element life and hang-off weight. Still other ram blocks are fitted with a tool steel-cutting surface to enable the ram BOPs to completely shear through drillpipe, hang the drillstring off on the ram blocks themselves and seal the wellbore. Obviously, such an action limits future options and is employed only as a last resort to regain pressure control of the wellbore. The various ram blocks can be changed in the ram preventers, enabling the well team to optimize BOP configuration for the particular hole section or operation in progress.
5002annular blowout preventer, blind ram, BOP stack, kick, snubbing, stripping
5003None
5004None
5005--
5006relative permeability
50071.n. [Geology]
5008A dimensionless term devised to adapt the Darcy equation to multiphase flow conditions. Relative permeability is the ratio of effective permeability of a particular fluid at a particular saturation to absolute permeability of that fluid at total saturation. If a single fluid is present in a rock, its relative permeability is 1.0. Calculation of relative permeability allows comparison of the different abilities of fluids to flow in the presence of each other, since the presence of more than one fluid generally inhibits flow.
5009absolute permeability, effective permeability, permeability, saturation
5010None
5011None
5012--
5013relative permeability
50142.n. [Well Completions]
5015A measurement of the ability of two or more fluid phases to pass through a formation matrix. The relative permeability reflects the capability of a specific formation to produce a combination of oil, water or gas more accurately than the absolute permeability of a formation sample, which is measured with a single-phase fluid, usually water.
5016None
5017None
5018None
5019--
5020retrograde condensation
50211.n. [Production Testing]
5022The formation of liquid hydrocarbons in a gas reservoir as the pressure in the reservoir decreases below dewpoint pressure during production. It is called retrograde because some of the gas condenses into a liquid under isothermal conditions instead of expanding or vaporizing when pressure is decreased.
5023condensate, reservoir pressure
5024None
5025None
5026--
5027root mean square velocity
50281.n. [Geophysics]
5029The value of the square root of the sum of the squares of the velocity values divided by the number of values, symbolized by vrms. The root-mean-square velocity is that of a wave through subsurface layers of different interval velocity along a specific raypath, and is typically several percent higher than the average velocity. The stacking velocity and the root-mean-square velocity approach equality when source-receiver offset approaches zero and layers are horizontal and isotropic.
5030Dix formula, raypath, stacking velocity, velocity
5031None
5032None
5033--
5034ram preventer
50351.n. [Well Workover and Intervention]
5036A classification of blowout preventer in which the pressure-control functions are achieved through the operation of hydraulically operated ram sets. Each ram set is configured as an opposing pair and, depending on function, are designed to close within the bore of the preventer. Ram preventers are commonly available in single-, double-, triple- and quad-ram configurations.
5037blowout preventer
5038None
5039None
5040--
5041relaxed filtrate oil mud
50421.n. [Drilling Fluids]
5043Anoil muddesigned and maintained with a minimum ofcolloid-sized solids, typically by omittingfatty-acid soapand lime, and minimizingorganophilicclays and fluid-loss additives. Relaxed filtrate oil mud increasesdrilling rate. A disadvantage is thatfilter cakeformed on sands is not tight, can quickly become very thick, and can cause pipe to stick bydifferential pressure.
5044differential pressure sticking, filtration, gilsonite, oil-mud emulsifier, organophilic clay
5045low colloid oil mud
5046None
5047--
5048returns
50491.n. [Drilling Fluids]
5050Mud that comes back to the surface and exits through the flowline after being pumped down the drillpipe. "Lost returns" is the situation in which some or all of the mud does not come back to the surface, which indicates that mud is being lost into weak, fractured or vugular formations downhole.
5051lost-circulation material, mud
5052None
5053None
5054--
5055rop
50561.n. [Drilling]
5057Abbreviation for rate of penetration. The speed at which the drill bit can break the rock under it and thus deepen the wellbore. This speed is usually reported in units of feet per hour or meters per hour.
5058antiwhirl bit, drill bit
5059None
5060rate of penetration
5061--
5062random error
50631.n. [Formation Evaluation]
5064A nonreproducible error that is generally imputable to the physics of the measurement. For example, the statistical errors in nuclear measurements are random errors.
5065measurement error, repeatability, sampling error, systematic error
5066None
5067None
5068--
5069relaxed filtrate oil mud
50701.n. [Drilling Fluids]
5071Anoil muddesigned and maintained with a minimum ofcolloid-sized solids, typically by omittingfatty-acid soapand lime, and minimizingorganophilicclays and fluid-loss additives. Relaxed filtrate oil mud increasesdrilling rate. A disadvantage is thatfilter cakeformed on sands is not tight, can quickly become very thick, and can cause pipe to stick bydifferential pressure.
5072differential pressure sticking, filtration, gilsonite, oil-mud emulsifier, organophilic clay
5073low-colloid oil mud
5074None
5075--
5076reverse circulating valve
50771.n. [Well Completions]
5078A downhole tool that is designed to enable communication between the tubing internal diameter and the annulus, typically for reverse circulation purposes, although conventional circulation often can also be undertaken. The valve design may be simple, enabling circulation without the ability to reset the tool until it is retrieved to surface, or be of a more complex design allowing several cycles between open and closed positions.
5079None
5080None
5081None
5082--