Oil and gas terminology · MLC-0103

Oil and gas terms: T (240)

T1The longitudinal relaxation time in nuclear magnetic resonance (NMR) logging, representing the time constant...
T2The transverse relaxation time in nuclear magnetic resonance (NMR) logging, representing the time constant...
TadpoleA graphical representation on a well log that displays the dip and azimuth of bedding planes or fractures...
TagTo make physical contact with a specific point or object in the wellbore using a wireline tool, coiled...
TailThe trailing portion of a logging tool's response curve, where the signal gradually returns to baseline after...
Tail buoyA floating marker deployed at the end of a marine seismic streamer cable to indicate its position and depth...
Tail cementThe final, denser portion of cement slurry pumped into a wellbore during cementing operations. This section...
Tail muteA seismic data processing step that zeroes out the signal on the far-offset traces of a shot gather...
Tail pipeA section of tubing or casing extending below a downhole tool, such as a packer or a liner hanger. It...
Taitel-DuklerA widely used flow regime map and correlation for predicting two-phase flow patterns in horizontal and...
Tall oilA viscous, dark-colored liquid by-product derived from the pulping of pine wood, primarily used as an...
TallyA detailed, sequential record of every pipe joint, tool, and piece of equipment run into or pulled out of a...
TAMEAn ether, tert-Amyl Methyl Ether, used as a component in reformulated gasoline to increase octane and reduce...
Tangential waveA type of shear wave where the particle motion is perpendicular to the direction of wave propagation and also...
TankA large container used for the storage of liquids or gases, such as crude oil, refined products, or produced...
Tank batteryA collection of storage tanks and associated equipment, such as separators, treaters, and pumps, located at a...
Tank bottomsThe accumulation of water, sediment, and heavy hydrocarbons that settles at the bottom of crude oil storage...
Tank calibrationThe process of accurately determining the capacity of a storage tank at incremental levels from bottom to...
Tank dikeA containment wall or berm constructed around a storage tank or group of tanks to prevent the escape of...
Tank tableA document or digital record that provides a precise correlation between the liquid level in a storage tank...
TankerA large vessel specifically designed for the bulk transport of liquid cargo, primarily crude oil or refined...
Tannic acidA naturally occurring organic compound derived from plants, used as a deflocculant and a fluid loss control...
TanninA class of astringent, bitter plant polyphenols that act as deflocculants and fluid loss control agents in...
Taper tapA fishing tool with a tapered, threaded profile designed to engage and retrieve lost or stuck tubulars from a...
Tapered cutoffA method used in petrophysical analysis to define a gradual transition zone for a property, rather than a...
Tapered stringA drill string or casing string composed of sections with different diameters or wall thicknesses, typically...
TAPSThe Trans-Alaska Pipeline System, an 800-mile long crude oil pipeline that transports oil from Prudhoe Bay on...
TARAn abbreviation for true amplitude recovery, a series of seismic data processing steps designed to compensate...
Tar sandA naturally occurring mixture of sand, clay, water, and bitumen, a very heavy and viscous form of petroleum...
Taylor bubblesLarge, bullet-shaped bubbles of gas that occupy nearly the entire cross-section of a pipe in slug flow or...
TCPTubing-conveyed perforating, a method for creating holes in the casing and cement sheath of a wellbore to...
TDAn abbreviation for Total Depth, which is the maximum depth reached in a wellbore, measured from the surface...
TDEMTime-domain electromagnetic (TDEM) method, a geophysical technique that measures the decay of induced eddy...
TEAn abbreviation for transverse electric, a mode of electromagnetic wave propagation where the electric field...
Technical evaluation agreement (TEA)A preliminary agreement between two or more companies that outlines the terms for sharing and evaluating...
Tectonic environmentThe geological setting defined by the style of crustal deformation resulting from the interaction of tectonic...
TectonicsThe study of the large-scale deformation and structural features of the Earth's crust, including the forces...
TectonismThe process of crustal deformation, including the formation of folds, faults, and other geological structures...
TelemetryThe process of transmitting measurement data from downhole logging tools to the surface in real time during...
Tell-taleA small port or indicator designed to show whether a seal or a packer has successfully set and is holding...
Telluric currentNaturally occurring electrical currents that flow within the Earth's subsurface, induced by variations in the...
Telluric-current methodA passive electromagnetic geophysical technique that measures naturally occurring electric currents flowing...
TEMTime-domain electromagnetic (TEM) method, a geophysical technique that involves transmitting a pulsed...
Temperature gradientThe rate at which temperature increases with depth in the Earth's crust, typically expressed in degrees...
Temperature logA continuous record of temperature versus depth in a wellbore, obtained by lowering a temperature sensor into...
Temperature stabilityThe ability of a drilling fluid to maintain its physical and chemical properties, such as viscosity, gel...
Temperature surveyA logging technique that measures the temperature profile along the length of a wellbore. A temperature...
Ten-minute gel strengthThe shear stress required to initiate flow in a drilling fluid after it has remained static for ten minutes...
Ten-second gel strengthThe shear stress required to initiate flow in a drilling fluid after it has remained static for ten seconds...
Tensile strengthThe maximum stress a material can withstand when subjected to a stretching or pulling force before it begins...
Tension-set packerA type of retrievable packer that is set by applying upward tension to the tubing string after it has been...
Tensor methodsMathematical techniques that use tensors, which are generalized vectors and matrices, to describe physical...
TEORThermal Enhanced Oil Recovery, a set of methods that introduce heat into a reservoir to reduce the viscosity...
Term leaseA mineral lease granted for a fixed period of time, after which it expires unless production in paying...
Ternary diagramA graphical representation used to show the compositions of three components in a system, where the sum of...
Terrain correctionAn adjustment applied to gravity or magnetic survey data to account for the gravitational or magnetic effects...
TerrestrialRelating to or originating from land environments, as opposed to marine or aquatic settings. Terrestrial...
Tertiary recoveryThe third stage of hydrocarbon production, implemented after the natural drive and secondary recovery methods...
Test separatorA specialized vessel used to separate and individually measure the flow rates of oil, gas, and water from a...
Tetrahedral layerA structural component of clay minerals, consisting of silicon atoms surrounded by four oxygen atoms, forming...
Texas deckThe main working floor of a drilling rig or production platform, located below the derrick floor on some...
TFNBThe temperature of the formation at no-flow conditions, representing the undisturbed or static temperature of...
TGThe total concentration of hydrocarbon gases, from methane to pentane, detected in the drilling fluid as it...
THAIToe-to-Heel Air Injection, an in-situ combustion process for heavy oil recovery where air is injected into a...
TheoreticalRelating to or based on abstract principles, concepts, and models rather than empirical observation or...
Thermal captureA nuclear interaction where a low-energy (thermal) neutron is absorbed by an atomic nucleus, which then...
Thermal diffusion lengthThe average distance a thermal neutron travels in a medium before being captured by an atomic nucleus. This...
Thermal gradientThe rate at which temperature increases with depth in the Earth's crust. This gradient influences the design...
Thermal maturityA measure of the extent to which organic matter in source rocks has been subjected to heat over geological...
Thermal neutron absorberA material or element that readily absorbs thermal neutrons, which are neutrons that have reached thermal...
Thermal neutron porosity measurementA logging technique that determines formation porosity by measuring the concentration of hydrogen atoms...
Thermal recoveryA category of enhanced oil recovery techniques that involve injecting heat into a reservoir to reduce the...
Thermal simulationA numerical modeling technique that predicts the behavior of heat and fluid flow in a reservoir during...
Thermally activated mud emulsionA type of invert-emulsion drilling fluid that remains thin and pumpable at surface temperatures but develops...
Thickening timeThe time required for a cement slurry to reach a specific consistency, indicating the onset of hydration and...
ThiefA device used to collect a representative sample of liquid from a storage tank at a specific depth. It...
Thief hatchA small, hinged opening on the top of a storage tank, typically equipped with a gasket and latch, that allows...
Thief zoneA formation interval with high permeability or fractures that absorbs drilling fluid from the wellbore...
ThinnerA chemical additive used in drilling fluids to reduce their viscosity and gel strength, improving flow...
ThixotropicDescribing a fluid that exhibits a time-dependent decrease in viscosity under shear stress, followed by a...
ThixotropyThe property of certain fluids to exhibit a decrease in viscosity when subjected to shear stress, and then to...
ThoriumA naturally occurring radioactive element whose concentration in rock is measured by spectral gamma ray...
Thousand standard cubic feet per dayA unit of measurement for the flow rate of gas, abbreviated as Mcfd. It represents a volume of one thousand...
Thread protectorA cap or sleeve placed over the threaded ends of drill pipe, casing, or tubing to prevent damage during...
Thread ruleA specialized measuring tool used to inspect the threads of tubular goods, such as drill pipe, casing, and...
ThreadformThe specific geometric profile of the threads on a pipe connection, including elements such as pitch, taper...
Three-component (3C) seismic dataSeismic data recorded by receivers that measure ground motion in three orthogonal directions: one vertical...
Three-dimensional (3D) seismic dataA set of seismic reflection data acquired over a surface area, providing a volumetric image of the subsurface...
Three-dimensional (3D) surveyA seismic acquisition program designed to collect data over a grid of closely spaced source and receiver...
Three-phase flowThe concurrent movement of oil, gas, and water as distinct but mixed phases within a reservoir, wellbore, or...
Three-phase separatorA pressure vessel designed to separate an incoming well stream into three distinct components: oil, gas, and...
Threshold velocityThe minimum fluid velocity required to move a production logging tool's spinner or flowmeter, below which the...
ThrottlingThe process of intentionally restricting the flow of a fluid to control its pressure, flow rate, or...
Through-conduitDescribing a valve design where the bore through the valve body is the same diameter as the pipeline...
Through-flowline (TFL)A system for performing well intervention operations, such as setting or retrieving plugs, shifting sleeves...
Through-tubingRelating to well intervention operations conducted through the existing production tubing without its removal...
Through-tubing gunA perforating gun designed with a small diameter to pass through the existing production tubing string in a...
Thrust faultA type of reverse fault where the hanging wall moves up and over the footwall, with a dip angle of less than...
TIA form of seismic anisotropy where the velocity of a wave depends on its direction of travel relative to a...
Tick markA small line or indicator on a log plot that denotes a specific depth or measurement interval. These marks...
TieThe correlation of seismic reflection data with well log data at a specific well location. This process...
Tie lineA line connecting the compositions of two coexisting phases in a phase diagram, indicating equilibrium...
Tieback linerA string of casing or liner that extends from the top of an existing liner up to the surface or to a higher...
Tieback packerA downhole tool used to seal the annulus between a liner top and the casing above it, or between a production...
Tieback stringA string of casing or tubing run from the surface to connect to a liner top or an existing casing string...
TightDescribing a reservoir rock with very low permeability, meaning fluids cannot flow through it easily under...
Tight emulsionA stable mixture of two immiscible liquids, such as oil and water, where one liquid is finely dispersed as...
Tight gasNatural gas produced from low-permeability sandstone, limestone, or dolomite reservoirs that require...
Tight holeA section of a wellbore where the diameter is slightly smaller than the drill bit or casing, making it...
Tight oilCrude oil produced from low-permeability reservoir rocks, such as shale or tight sandstone, that requires...
TIHThe operation of lowering a drill string, casing, or a wireline tool assembly into the wellbore. Tripping In...
Time after bitThe elapsed time between when the drill bit passes a certain depth and when a logging-while-drilling (LWD) or...
Time domainThe representation of a signal's amplitude as a function of time, as opposed to its frequency components. In...
Time migrationA seismic data processing technique that repositions dipping reflectors to their true subsurface locations...
Time sliceA horizontal cross-section through a three-dimensional (3D) seismic data volume at a constant two-way travel...
Timed slug analysisA method used in production logging to determine individual phase flow rates in a multiphase flow stream. A...
Time-domain electromagnetic methodA geophysical technique that measures the transient decay of secondary electromagnetic fields induced in the...
Time-lapseDescribing a set of measurements taken over the same location at different points in time to monitor changes...
Time-lapse seismic dataSeismic data acquired repeatedly over the same subsurface area at different points in time, typically to...
TitrateTo perform a chemical analysis by gradually adding a solution of known concentration (the titrant) to a...
TitrationA quantitative chemical analysis method used to determine the concentration of a specific substance in a...
TIVAn acronym for Transversely Isotropic with a Vertical axis of symmetry, describing a type of anisotropic...
TMAn abbreviation for transverse magnetic, a mode of electromagnetic wave propagation where the magnetic field...
TOCTotal organic carbon, a measure of the amount of organic material present in a rock, expressed as a weight...
Toe to heel air injectionA variation of in-situ combustion where air is injected into the toe (bottom) of a horizontal well, and...
TomographyA method for imaging the subsurface by measuring the traveltimes of seismic waves that pass through a volume...
TongsLarge wrenches used by the rig crew to apply torque for making up or breaking out threaded connections on...
Tool jointA heavy, threaded coupling welded to the ends of a section of drill pipe, providing a high-strength...
Tool stringAn assembly of logging instruments connected together and lowered into a wellbore to acquire formation data...
ToolfaceThe azimuthal orientation of a downhole drilling tool, such as a bent sub or a steerable motor, relative to a...
ToolpusherThe senior supervisor on a drilling rig, responsible for all drilling operations and crew management. This...
Top driveA power swivel and motor assembly suspended from the derrick that rotates the drill string from the top...
Top entryA valve design that allows for internal components to be accessed and serviced from the top of the valve body...
Top leaseA new oil and gas lease that becomes effective only after an existing, underlying lease expires or is...
Top log intervalThe uppermost depth at which data acquisition begins for a specific wireline logging run in a well. This...
Topographic mapA detailed map that illustrates the surface features of an area, including elevation, relief, and landforms...
Tornado chartA sensitivity analysis tool that graphically displays the impact of input parameters on an output variable...
Torque flowmeterA downhole tool that measures fluid flow rate by sensing the torque exerted by the flowing fluid on a...
TortuosityA measure of the deviation of fluid flow paths from a straight line within a porous medium, such as a...
Total depth (TD)The maximum depth reached in a wellbore, measured from the surface to the bottom of the hole. This depth can...
Total hardness testA chemical test performed on drilling fluid filtrate to determine the concentration of divalent cations...
Total organic carbonA measure of the amount of carbon present in a rock sample that is bound in organic compounds, rather than in...
Total porosityThe fraction of the bulk volume of a rock that is occupied by pore space, regardless of whether the pores are...
Total solidsThe combined weight of all solid materials, both suspended and dissolved, present in a drilling fluid sample...
TourA scheduled work period or shift for drilling rig personnel, typically lasting 8 or 12 hours. Rig operations...
TraceA single recording of seismic data from one receiver, representing the ground motion over time at that...
TracerA substance added to drilling fluid in small, detectable quantities to track its movement or identify its...
Tracer measurementThe technique of injecting a detectable substance into a fluid stream to track its movement and distribution...
Tracer-ejector measurementA production logging technique where a tracer is actively injected or ejected into the wellbore fluid at a...
Tracer-loss measurementA technique used in production logging to identify zones where injected fluids are being lost from the...
TrackA vertical column on a well log plot where specific logging curves or data are displayed. A typical log...
Training dataA dataset used to teach a machine learning model to recognize patterns, make predictions, or perform specific...
Trans-Alaska Pipeline SystemA major oil transportation system that carries crude oil from the North Slope of Alaska to the port of Valdez...
Transfer learningA machine learning method where a model developed for a task is reused as the starting point for a model on a...
Transform faultA type of strike-slip fault that accommodates relative horizontal motion between two tectonic plates. These...
Transformer modelA neural network architecture that relies on a self-attention mechanism to weigh the influence of different...
TransgressionA geological event where sea level rises relative to the land, causing the shoreline to move inland and...
TransgressiveDescribing a geological sequence or event characterized by a relative rise in sea level, leading to the...
Transgressive surfaceA marine flooding surface that marks a period of rising sea level and landward migration of the shoreline...
Transient drainage radiusThe radius of the reservoir area that is actively being affected by pressure changes due to production or...
Transient electromagnetic methodA geophysical technique that measures the decay of induced eddy currents in the Earth after a primary...
Transient pressureThe time-dependent pressure variation within a reservoir that occurs in response to a change in production or...
Transient rate and pressure test analysisThe interpretation of pressure and flow rate data collected during a well test to determine reservoir and...
Transient-pressure responseA reservoir's dynamic pressure behavior measured at a well following a change in flow rate, such as starting...
Transient-pressure testingA method of well testing that involves inducing a change in the flow rate of a well and then monitoring the...
Transit timeThe time it takes for a seismic wave to travel a specific distance through a rock formation. It is the...
Transition flowA flow regime in a wellbore or pipeline that exists between laminar flow and turbulent flow, characterized by...
Transition zoneA geological interval in a reservoir where the saturation of hydrocarbons gradually changes from 100% to 0%...
Transmission tomographyA technique that uses the attenuation or travel time of waves passing through a medium to create a...
TranspressionA type of strike-slip deformation that also involves a component of compression perpendicular to the fault...
TranstensionA type of deformation that combines strike-slip motion with a component of extension, resulting in both...
Transverse electric modeA type of electromagnetic wave propagation where the electric field vector is perpendicular to the direction...
Transverse isotropyA type of seismic anisotropy where the elastic properties of a medium are the same in all directions within a...
Transverse magnetic modeA type of electromagnetic wave propagation where the magnetic field vector is perpendicular to the direction...
Transverse relaxationThe process by which the transverse magnetization of nuclear spins decays after being perturbed by a...
TrapA geological configuration of porous reservoir rock and impermeable seal rock that prevents hydrocarbons from...
Trapped oilHydrocarbons that remain immobile within the pore spaces of a reservoir rock after primary and secondary...
Travel jointA specialized pipe connection designed to compensate for vertical movement between two fixed points, such as...
Traveling blockA large, multi-sheave pulley system that moves up and down in the derrick, supporting the drill string and...
Traveling slipsA component of a power tong or casing running tool that grips the tubular being run into the well. These...
Traveling snubbersThe moving components of a snubbing unit that directly engage and manipulate the pipe string. These include...
Traveling valveA component within a sucker rod pump that opens on the upstroke to allow fluid to enter the pump barrel and...
TraveltimeThe total time elapsed for a seismic wave to propagate from its source to a receiver, including reflections...
TreaterA vessel used in production facilities to separate oil, gas, and water from a produced well stream emulsion...
Treating ironA system of temporary, high-pressure pipes, swivels, elbows, and other fittings used to connect pumping...
Treatment fluidA liquid or gas pumped into a wellbore to alter the characteristics of the reservoir rock or the fluids...
Tree saverA protective device installed on top of the wellhead or Christmas tree during drilling or workover operations...
TrendA general direction or orientation of a geological feature, such as a fault system, a fold axis, or a...
TripThe process of pulling the drill string out of the wellbore and then running it back in, typically to change...
Trip gasGas that enters the wellbore from the formation during a trip out of the hole, as the hydrostatic pressure of...
Trip outTo withdraw the drill string from the wellbore, typically to change the drill bit or perform other downhole...
Trip pillA small volume of high-viscosity, weighted drilling fluid pumped into the drill string before tripping out of...
Triplex pumpA positive displacement pump equipped with three plungers or pistons that reciprocate to move fluid. This...
Tripping pipeThe operation of pulling the drill string out of the wellbore and subsequently running it back in, usually to...
TroughThe lowest point of a wave cycle, representing a negative amplitude in a seismic trace. In seismic data...
True amplitude recoveryA series of seismic data processing steps designed to compensate for factors that alter the recorded...
True dipThe maximum angle of inclination of a bedding plane or other planar geological feature from the horizontal...
True resistivityThe actual electrical resistivity of a formation, representing its inherent ability to impede the flow of...
True stratigraphic thicknessThe perpendicular distance between the upper and lower bounding surfaces of a rock layer, measured normal to...
True vertical depthThe vertical distance from a reference point, usually the rotary kelly bushing (RKB) at the surface, to a...
True vertical thicknessThe vertical distance between the top and bottom of a stratigraphic unit, measured along a vertical line...
Trunk lineA large-diameter pipeline that transports crude oil, natural gas, or refined products over long distances...
TrunnionA cylindrical pin or shaft projecting from the side of a larger body, serving as a pivot or mounting point...
Tube waveA guided wave that propagates along the borehole wall, generated by the interaction of seismic waves with the...
Tubing broachA downhole tool with hardened, sharp-edged surfaces run on wireline or slickline to clear minor obstructions...
Tubing displacementThe volume of fluid that occupies the inside of the production tubing in a wellbore. This volume must be...
Tubing gradeA classification of tubing material based on its mechanical properties, primarily yield strength and tensile...
Tubing hangerA component installed in the wellhead that supports the weight of the tubing string and provides a seal...
Tubing headA spool-shaped component that is part of the wellhead assembly, installed on top of the casing head. It...
Tubing jobAn operation involving the running, pulling, or manipulation of production tubing within a wellbore. This...
Tubing jointA single length of pipe, typically 25 to 30 feet long, that is threaded at both ends and connected to other...
Tubing performance curve (TPC)A graphical representation that shows the relationship between the flow rate of fluids through the production...
Tubing pressureThe fluid pressure measured at the surface within the production tubing string, which carries oil and gas...
Tubing puncherA downhole tool used to create a hole in the production tubing string, typically to equalize pressure across...
Tubing seal assemblyA component of a downhole packer that provides a pressure-tight seal between the production tubing and the...
Tubing testing toolA downhole device run as part of the tubing string to allow for pressure testing of the tubing and its...
Tubing threadThe helical ridges cut into the ends of tubing joints that allow them to be screwed together to form a...
Tubing-conveyed perforating (TCP)A perforating method where the gun string is attached to the bottom of the production tubing and run into the...
Tubing-end locator (TEL)A downhole tool used to precisely determine the depth of the end of the production tubing string. This device...
Tubingless completionA well completion method where production tubing is not run inside the casing. Instead, the casing itself...
Tubing-retrievable safety valve (TRSV)A downhole safety device installed as an integral part of the production tubing string, designed to...
Tubular jarA downhole tool run as part of a workover or fishing string that delivers a sudden, high-impact axial blow to...
TubularsA collective name for the cylindrical steel pipes used in drilling and completing a well. This category...
TuffA fine-grained, porous rock formed from volcanic ash and dust ejected during an eruption, which then settles...
TuffaceaousDescribing a rock or sediment that contains a substantial proportion of volcanic ash or tuff fragments. These...
Tuning effectThe phenomenon where the apparent thickness of a thin bed, as observed on a seismic section, is distorted due...
TurbiditeA sedimentary deposit formed by a turbidity current, which is a dense, gravity-driven flow of sediment and...
Turbidity currentA dense, fast-moving current of sediment-laden water that flows down a submarine slope under the influence of...
Turbulent flowA fluid flow regime characterized by chaotic, random fluctuations and eddies, rather than the smooth...
TurnkeyA type of drilling contract where the contractor agrees to drill a well to a specified depth and condition...
Twist offA mechanical failure of the drill string where a section of pipe or a tool joint breaks due to excessive...
Two-dimensional seismic dataSeismic data acquired along a single line, providing a cross-sectional view of the subsurface. The seismic...
Two-dimensional surveyA seismic acquisition program where sources and receivers are deployed along a single line to generate a...
Two-pass methodA technique in production logging where a logging tool is run down the wellbore and then pulled back up...
Two-phase flowThe simultaneous flow of two immiscible fluids, such as oil and water, or a liquid and a gas, such as oil and...
Two-phase separatorA vessel designed to separate a mixture of liquid and gas into two distinct phases. Gas typically exits from...
Two-way traveltimeThe total time elapsed for a seismic wave to travel from a source, reflect off a subsurface interface, and...
TWTThe abbreviation for two-way traveltime, which is the total time elapsed for a seismic wave to travel from a...
Type curve analysisA graphical well test interpretation method that involves matching measured pressure and rate data to a...
Type curvesA set of pre-plotted graphical solutions representing the theoretical pressure response of a well under...

240 of 4,499 terms in Oil and gas terminology (MLC-0103). Request the full dataset.