Oil and gas terminology · MLC-0103

Oil and gas terms: E (141)

• Early time transient dataThe pressure response recorded immediately after a change in flow rate, such as the beginning of a flow...
• EarthquakeA sudden and rapid shaking of the Earth's surface caused by the release of energy in the Earth's lithosphere...
• Easy to disperseDescribing a well cement that is readily dispersed by a dispersant additive, so the viscosity of its slurry...
• Easy to disperse in saltDescribing a well cement that a dispersant additive disperses readily when the slurry is mixed with water...
• EccentralizerA mechanical device attached to a logging tool string to force it against one side of the wellbore. It...
• EccentricDescribing a component or condition that is not centered on an axis or another object. In drilling, an...
• EccentricityThe state or degree of being off-center, particularly when one circular object is placed within another. In...
• ECDThe effective circulating density, which is the density of the drilling fluid when it is circulating in the...
• Echo spacingThe time between successive spin echoes in the CPMG pulse sequence used by an NMR logging tool, set by the...
• EDAExtensive dilatancy anisotropy, a model describing seismic anisotropy caused by the alignment of fluid-filled...
• Eddy currentA localized electric current induced within a conductor by a changing magnetic field. These currents create...
• Eddy current measurementA non-contact method used in casing inspection logs to detect and quantify metal loss or defects in tubulars...
• Edge aiArtificial intelligence processing that occurs directly on local devices or at the network edge, rather than...
• Edge computingA distributed computing architecture that processes data close to its source, such as on a rig or at a remote...
• EDTAEthylenediaminetetraacetic acid, a chelating agent used in drilling fluids to sequester metal ions...
• Effective laminar flowA flow regime used when planning primary cement placement, in which the spacer and cement move through the...
• Effective medium theoryA theoretical approach that estimates the macroscopic properties of a heterogeneous material, such as a rock...
• Effective permeabilityThe ability of a rock to transmit a particular fluid when other immiscible fluids are also present in the...
• Effective porosityThe fraction of the total rock volume that consists of interconnected pore spaces through which fluids can...
• Effective shot densityThe number of perforations per foot that are open and contributing to fluid flow from the reservoir into the...
• Effective velocityThe velocity of the fluid relative to the moving tool in spinner flowmeter interpretation, equal to the...
• Effective water saturationThe fraction of the effective pore volume occupied by water, where effective porosity leaves out the water...
• Effective wellbore radiusA theoretical radius that represents the effective flow capacity of a well, accounting for any damage or...
• EigenvectorA non-zero vector that, when a linear transformation is applied to it, changes only by a scalar factor, known...
• ElasticRelating to the property of a material, such as rock, to deform instantly when a stress is applied and to...
• Elastic constantsA set of parameters that describe the elastic behavior of a material, quantifying its resistance to...
• Elastic deformationA temporary change in the shape or volume of a rock body in response to applied stress, where the rock...
• Elastic limitThe maximum stress or force per unit area that a rock or other solid material can withstand without...
• Elastic moduliMeasures of a material's stiffness or resistance to elastic deformation under applied stress. Key elastic...
• Elastic neutron scatteringA nuclear interaction that forms the primary measurement principle of neutron porosity logging tools...
• Elastic waveA wave that propagates through a material by causing temporary deformation of the medium, with the material...
• ElasticityThe physical property of a material that allows it to deform reversibly under stress and return to its...
• Electric probeA downhole logging tool that uses electrical principles to measure properties of the wellbore environment or...
• Electric submersible pumpA downhole artificial lift system consisting of a motor, protector, intake, and pump stages, all designed to...
• Electrical anisotropyThe condition where the electrical resistivity of a rock formation varies with the direction of measurement...
• Electrical conductivityA measure of a material's ability to conduct electric current, representing the inverse of electrical...
• Electrical couponA small, pre-weighed metal specimen exposed to a corrosive environment within a pipeline or vessel to monitor...
• Electrical double layerA structure that forms at the interface between a solid surface and an electrolyte solution, consisting of...
• Electrical impedance probeA downhole logging tool that measures the opposition to alternating current flow in the wellbore fluids or...
• Electrical logA well log that measures the electrical properties of subsurface formations, primarily resistivity and...
• Electrical permittivityA measure of a material's ability to store electrical energy in an electric field, representing its...
• Electrical resistance probeA device used to monitor corrosion by measuring the change in electrical resistance of a metallic element...
• Electrical resistivityA fundamental electrical property of a material that quantifies how strongly it opposes the flow of electric...
• Electrical stability testA measurement performed on oil-based drilling fluids to determine the stability of the emulsion by applying...
• Electrical surveyThe process of measuring the electrical properties of subsurface formations within a borehole using...
• Electrode deviceA logging tool component that uses electrodes to measure the electrical properties of the formation. These...
• Electrode resistivityA method of measuring the electrical resistivity of a formation using electrodes placed on a logging tool...
• Electrodynamic brakeA braking system that uses electromagnetic forces to slow or stop motion, converting kinetic energy into...
• ElectrohygrometerAn instrument used to measure the water vapor content or relative humidity of a gas stream, often in natural...
• Electrokinetic potentialThe electrical potential that develops across an interface between a solid and a fluid when there is relative...
• Electromagnetic caliperA downhole tool that measures the internal diameter of casing or tubing using electromagnetic principles. It...
• Electromagnetic heatingA method of heating reservoir fluids by applying electromagnetic energy, typically radio frequency or...
• Electromagnetic methodA class of geophysical techniques that use the propagation and interaction of electromagnetic fields to...
• Electromagnetic propagationThe transmission of high-frequency electromagnetic waves through subsurface formations to measure dielectric...
• Electromagnetic propagation measurementA logging technique that uses high-frequency electromagnetic waves to determine the dielectric properties of...
• Electromagnetic thicknessA casing and tubing inspection measurement in which a transmitter coil induces eddy currents in the pipe wall...
• Elemental capture spectroscopyA nuclear logging technique that measures the gamma rays emitted by formation elements after they capture...
• Elevation correctionA static correction applied to seismic or potential field data to compensate for variations in the elevation...
• ElevatorA heavy-duty clamping device used to hoist and lower tubulars, such as drill pipe, casing, or tubing, into...
• Embedded waveletThe effective seismic waveform that is convolved with the Earth's reflectivity series to form a recorded...
• EmbeddingA numerical representation of text, images, or other data that captures semantic relationships and contextual...
• EmbrittlementA process that causes a material, typically a metal, to lose its ductility and become brittle, making it more...
• Emergency shutdown valve (ESDV)A safety valve designed to stop the flow of hazardous fluids in an emergency situation. These valves are...
• Emergent behaviorComplex, system-level patterns or capabilities that arise from the interactions of many simple components...
• EmpiricalDerived from observation or experiment rather than from theory or pure logic. Empirical models and...
• EmulsifierA chemical additive that facilitates the formation and stabilization of an emulsion, which is a mixture of...
• EmulsionA dispersion of one immiscible liquid within another, where tiny droplets of one liquid are suspended...
• Emulsion flowA multiphase flow regime where one immiscible liquid is dispersed as droplets within another continuous...
• Emulsion mudA drilling fluid system where one liquid phase is dispersed as fine droplets within another continuous liquid...
• En echelonDescribing a series of short, parallel, or subparallel geological features that are offset from each other...
• EncapsulationThe process of surrounding drill cuttings with a protective layer of polymer or other material to prevent...
• EncryptionThe process of converting information or data into a code to prevent unauthorized access, using an algorithm...
• End pointThe specific condition or measurement that signals the completion of a chemical reaction or a treatment...
• Endfire arrayA layout of transmitting and receiving antennas in an electromagnetic propagation tool in which each...
• Endless tubingA continuous, jointless string of flexible steel or composite pipe spooled on a large reel, used for well...
• EndpointThe specific condition or measurement that signals the completion of a chemical reaction or a treatment...
• Enhanced diffusionA technique in nuclear magnetic resonance logging that uses an unusually long echo spacing to amplify the...
• Enhanced oil recoveryA set of advanced techniques used to recover additional crude oil from a reservoir after primary and...
• Entrained gasGas bubbles suspended within a liquid, such as drilling mud or completion fluid, that do not readily separate...
• Entrance holeThe opening created by a perforating charge in the casing wall, through which the shaped charge jet passes to...
• Environmental correctionsAdjustments applied to raw logging tool measurements to compensate for the effects of borehole conditions and...
• EolianDescribing geological processes, sediments, or landforms associated with the action of wind. Eolian transport...
• EORA set of advanced techniques used to increase the amount of crude oil that is extracted from a reservoir...
• EPAThe Environmental Protection Agency, a United States federal agency responsible for protecting human health...
• Epanechnikov kernelA specific type of kernel function used in non-parametric statistics, particularly for kernel density...
• Epithermal neutron porosity measurementA logging technique that measures the concentration of hydrogen in a formation by detecting epithermal...
• EpmEquivalent parts per million, a unit of concentration used in drilling fluid analysis, particularly for...
• Epsilon (ε)A Thomsen parameter that quantifies the anisotropy of P-wave velocity in the horizontal direction relative to...
• Equalizing loopA bypass line of pipe and valves installed around a primary, high-pressure valve, such as a gate valve on a...
• Equalizing valveA small valve designed to balance pressure across a downhole tool or component before it is opened or...
• Equation of stateA mathematical relation linking the pressure, volume and temperature of a fluid, together with its...
• Equipotential methodAn electrical surveying technique used to map the shape of conductive subsurface bodies. The method involves...
• Equivalent circulating densityThe effective density exerted by a drilling fluid column when it is circulating, accounting for the...
• Equivalent conductanceA measure of the conductivity of an electrolyte solution, normalized by the concentration of the dissolved...
• Equivalent sackThe mass of a blend of Portland cement with fly ash or another pozzolan that has the same absolute volume as...
• Equivalent water resistivityA calculated value representing the effective resistivity of the formation water in a shaly sand reservoir...
• Equivalent weightThe mass of a substance that combines with or is equivalent to a fixed amount of another substance, typically...
• ERDAn acronym for extended reach drilling, a technique used to drill wells with a horizontal displacement...
• ErodeTo wear away rock or soil by the action of natural forces such as water, wind, or ice. This process removes...
• ErosionThe geological process by which surface material, such as rock or soil, is worn away and transported by...
• Erosion corrosionA form of material degradation that occurs when mechanical erosion, caused by the flow of abrasive fluids or...
• ErrorThe difference between a measured or calculated value and the true value of a parameter, arising from...
• ES testThe Emulsion Stability test, a laboratory procedure used to determine the electrical stability of an...
• Escape lineA cable or rope running from the derrick's monkey board or crown platform to an anchor point on the ground...
• ESPAn electrical submersible pump, a downhole artificial lift system used to increase the flow of liquids from a...
• Estimated ultimate recoveryThe total quantity of hydrocarbons, either oil or gas, that is projected to be recovered from a reservoir or...
• EstuarineRelating to or formed in an estuary, which is a semi-enclosed coastal body of water where fresh river water...
• EstuaryA semi-enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a...
• Eta (η)A parameter in seismic anisotropy that describes the anellipticity of P-wave moveout for transversely...
• Euclidian dimensionThe standard integer dimension of a geometric object in Euclidean space, representing the number of...
• Euclidian distanceA measure of the straight-line distance between two points in a multi-dimensional space, calculated using the...
• EustasyGlobal changes in sea level caused by variations in the volume of water in the oceans or the capacity of...
• EustaticDescribing global changes in sea level that affect all oceans simultaneously, independent of local tectonic...
• Eustatic sea levelThe global average sea level, which changes due to variations in the volume of ocean water or the capacity of...
• Evaporation pitAn unlined or lined earthen impoundment used to dispose of produced water or other liquid waste by allowing...
• EvaporiteA sedimentary rock formed by the precipitation of mineral salts from evaporating water. These deposits occur...
• EvaporiticDescribing a sedimentary rock, mineral, or depositional environment associated with the precipitation of...
• Evening tourA specific work shift on a drilling rig, typically referring to the period from late afternoon or early...
• EventA coherent reflection or refraction arrival observed on a seismic record, representing energy that has...
• Excavation effectA decrease in the apparent neutron porosity below the value expected from the hydrogen indices of the pore...
• Exit velocityThe speed at which drilling fluid exits the nozzles of a drill bit. This velocity is a function of the flow...
• Expanding cementA type of cement slurry formulated to increase slightly in volume after setting, rather than shrinking. This...
• Expanding gate valveA type of gate valve that uses a two-piece gate assembly designed to expand and create a tight seal against...
• Expansion jointA tubular device installed in a tubing string to compensate for changes in length due to thermal expansion or...
• ExpectationThe probability-weighted average of all possible values of a random variable, equal to its long-run average...
• Expendable gunA perforating gun designed to be left in the wellbore after firing, rather than being retrieved. These guns...
• Expendable plugA temporary plug placed in the bottom of a tubing string or packer bore so the tubing can be pressure tested...
• Expert systemA computer program that emulates the reasoning of a human specialist to solve problems within a specific...
• ExplaniabilityThe degree to which the internal workings and outputs of a machine learning model can be understood by...
• ExplorationThe process of searching for new hydrocarbon accumulations, involving geological and geophysical studies to...
• Exploration playA concept describing a group of potential hydrocarbon accumulations that share common geological...
• ExploratoryRelating to the initial phase of oil and gas operations aimed at discovering new hydrocarbon accumulations...
• Explosive seismic dataSeismic data acquired using explosive charges as the energy source to generate seismic waves. The detonation...
• Extended reach drillingA drilling technique characterized by wells with a horizontal displacement that is substantially greater than...
• Extended spreadA seismic acquisition geometry where the distance between the source and receivers is significantly larger...
• Extensive dilatancy anisotropyA model describing seismic anisotropy caused by the preferred orientation of fluid-filled microcracks or...
• External cutterA downhole tool used to cut tubing or casing from the outside diameter. It is run into the wellbore and...
• External disturbance fieldMagnetic or gravitational fields originating from sources outside the Earth's interior, such as solar...
• External phaseThe continuous liquid phase in an emulsion, which surrounds and suspends the dispersed internal phase. In an...
• External pulling toolA wireline or coiled tubing tool designed to retrieve downhole equipment by engaging an external fishing neck...
• External upsetA localized thickening of the pipe wall at the ends of tubing or casing joints, created by forging. This...

141 of 4,469 terms in Oil and gas terminology (MLC-0103). Request the full dataset.