Oil and gas terminology · MLC-0103

Oil and gas terms: G (184)

• GainThe amplification applied to a seismic signal to increase its amplitude for recording and processing. As...
• GalA unit of acceleration equal to one centimeter per second squared (cm/s²), commonly used in gravimetry. It is...
• GalenaA naturally occurring lead sulfide mineral, sometimes used as a high-density weighting agent in drilling...
• GallingA form of surface damage that occurs when two metal surfaces slide against each other under pressure, causing...
• Galvanic anodesSacrificial metal blocks, such as zinc or magnesium, that protect steel structures from corrosion by...
• Gamma (γ)A Thomsen parameter measuring the anisotropy of shear-wave velocity in a transversely isotropic medium with a...
• Gamma ray densitometerA tool containing a gamma-ray source and a detector on either side of a fluid sampling path, which measures...
• Gamma ray interactionsThe physical processes by which high-energy photons (gamma rays) lose energy as they pass through matter in a...
• Gamma ray logA well log that measures the natural radioactivity of formations encountered in a borehole. Shales and clays...
• Gamma-gamma logA well log that measures the density of a formation by emitting gamma rays into the rock and detecting the...
• Garrett Gas TrainAn apparatus used for the quantitative analysis of soluble sulfide and carbonate concentrations in drilling...
• Gas anchorA device installed at the bottom of a sucker rod pump intake to separate free gas from the produced liquid...
• Gas bearingDescribing a rock formation or reservoir zone that contains natural gas within its pore spaces. The gas...
• Gas busterA piece of surface equipment designed to separate gas from drilling mud, particularly when drilling through...
• Gas capA layer of free natural gas that accumulates above an oil column in a petroleum reservoir, trapped by an...
• Gas chimneyA vertical column of disturbed seismic reflections and attenuated amplitudes in seismic data, interpreted as...
• Gas condensateA hydrocarbon mixture that exists as a gas in the reservoir but condenses into a liquid (condensate) as...
• Gas coningThe upward movement of free gas into a producing oil wellbore, forming a cone shape in the reservoir. This...
• Gas deviation factorA dimensionless correction factor that accounts for the non-ideal behavior of natural gases at high pressures...
• Gas driveA natural reservoir drive mechanism where the expansion of dissolved gas or a free gas cap provides the...
• Gas formation volume factorThe ratio of the volume of natural gas at reservoir conditions to its volume at standard surface conditions...
• Gas gravityThe ratio of the molecular weight of a gas to the molecular weight of air, both measured at the same...
• Gas holdup logA measurement of the volume fraction of gas in a multiphase flow stream within a wellbore or pipeline...
• Gas hydrateA crystalline solid formed from natural gas and water molecules under conditions of high pressure and low...
• Gas in solutionNatural gas dissolved within crude oil under reservoir pressure and temperature conditions. As reservoir...
• Gas injectionAn enhanced oil recovery (EOR) method that involves injecting natural gas, carbon dioxide, or nitrogen into a...
• Gas interferenceThe adverse effect on a downhole pump's performance caused by free gas entering the pump intake along with...
• Gas liftAn artificial lift method that injects high-pressure gas into the production tubing of an oil well to reduce...
• Gas lockA condition in a downhole pump, typically a sucker rod pump, where free gas enters the pump chamber and...
• Gas migrationThe upward movement of gas through a column of drilling fluid or cement in the annulus of a wellbore. This...
• Gas processing plantA facility that purifies raw natural gas by removing impurities and separates the gas stream into its...
• Gas sandA porous and permeable sandstone whose pore space holds natural gas beneath an impermeable cap rock. On well...
• Gas separatorA pressure vessel at the surface designed to separate a produced well stream into its constituent liquid and...
• Gas shaleA fine-grained sedimentary rock, rich in organic matter, that serves as both the source rock and reservoir...
• Gas showAn indication of natural gas encountered during drilling operations, detected by gas sensors in the drilling...
• Gas volume fraction (GVF)The ratio of the volume occupied by the gas phase to the total volume of a multiphase fluid mixture at a...
• Gas wellA well drilled to produce natural gas from a subsurface reservoir. The primary product from such a well is...
• Gas-cap driveA natural reservoir drive mechanism where an overlying gas cap expands to push oil toward production wells as...
• Gas-cut mudDrilling fluid that has become contaminated with natural gas from the formation, reducing its density and...
• GasdriveA natural reservoir drive mechanism where the expansion of dissolved gas or a free gas cap provides the...
• Gas-lift mandrelA specialized tubular device installed as part of the production tubing string in a well equipped for gas...
• Gas-lift valveA pressure-operated device installed in a gas-lift mandrel within the production tubing, which controls the...
• Gas/liquid ratio (GLR)The ratio of the volume of gas to the volume of liquid produced from a well, typically measured at standard...
• Gas-oil contactThe interface within a reservoir where free gas overlies crude oil. This boundary is defined by the pressure...
• Gas/oil ratio (GOR)The volume of gas produced from a well, measured at standard temperature and pressure, divided by the volume...
• Gas-proneDescribing a petroleum system or a source rock that is more likely to generate natural gas than crude oil...
• Gas-solubility factorA coefficient that quantifies the volume of gas that can dissolve in a given volume of oil at specific...
• Gas-water contactThe interface or boundary surface within a reservoir where a column of natural gas overlies formation water...
• Gas-well deliverabilityThe maximum rate at which a gas well can produce gas against a specified backpressure at the wellhead. This...
• Gaswell gasNatural gas produced from a well that primarily yields gas, with little or no associated crude oil. This gas...
• Gaswell liquidsHydrocarbons that are in a liquid state at surface conditions but exist as a gas in the reservoir, produced...
• Gate valveA type of valve that uses a flat gate or wedge-shaped disc, which slides perpendicular to the flow path, to...
• GatherA collection of seismic traces that share a common attribute, such as a common midpoint (CMP), common shot...
• Gathering linesA network of relatively small-diameter pipelines that collect crude oil, natural gas, or produced water from...
• Gathering systemA network of pipelines, compressors, and processing equipment that collects raw hydrocarbons from multiple...
• Gauge holeA wellbore that has been drilled to the same diameter as the drill bit that created it. A hole is considered...
• Gauge pressureA pressure measurement relative to the local atmospheric pressure, representing the difference between the...
• Gauge ringA cylindrical tool run on wireline or coiled tubing into a wellbore to verify that the tubing or casing is...
• Gauge tankA calibrated vessel of a known volume used at the wellsite to accurately measure the flow rate of oil or...
• Gaussian collocated cosimulationA geostatistical simulation technique used to generate multiple realizations of a primary variable...
• Gaussian techniquesA class of statistical and geostatistical methods that assume data or variables follow a Gaussian (normal)...
• GelA semi-solid, jelly-like state of a drilling fluid that forms when the fluid is static, exhibiting a...
• Gel strengthA measure of the attractive forces between the suspended particles in a drilling fluid when it is at rest...
• GelationThe process by which a drilling fluid develops a semi-solid, jelly-like structure when left undisturbed...
• Gelled mudA drilling fluid that has developed a semi-solid, jelly-like consistency due to its thixotropic properties...
• Gelled-up mudA drilling fluid that has developed an excessively strong gel structure when static, making it difficult to...
• Gels, see Gel
• GenerationThe process by which organic matter buried in sedimentary rocks is transformed into hydrocarbons (oil and...
• Generative aIA type of artificial intelligence that can produce new content, such as text, images, audio, or code, that...
• Geochemical logA well log that provides elemental concentrations of the formation, typically derived from the spectral...
• GeochemistryThe study of the chemical composition of the Earth and its processes, including the distribution and...
• GeochronologyThe scientific discipline focused on determining the absolute age of rocks, minerals, and geological events...
• GeologicRelating to the science of geology, which studies the Earth's physical structure, substance, history, and the...
• Geologic mapA specialized map that displays the distribution of different rock units, geological structures, and other...
• Geologic time scaleA chronological system of measurement relating stratigraphy to time, used by geoscientists to date rock...
• GeologicalRelating to the study of Earth's physical structure, substance, history, and the processes that act upon it...
• GeologistA scientist who studies the Earth's physical structure, processes, and history, including its rocks...
• GeologyThe scientific study of the Earth's physical structure, its constituent rocks, and the processes by which...
• Geomagnetic polarity reversalA phenomenon where the Earth's magnetic field flips, causing the magnetic north and south poles to swap...
• Geomagnetic polarity time scaleA chronological sequence of reversals in the Earth's magnetic field, established by dating the magnetic...
• Geomagnetic secular variationThe slow, long-term change in the Earth's magnetic field over decades to centuries, distinct from daily...
• GeomechanicsThe study of the mechanical behavior of rock and soil, including their response to stress, strain, and fluid...
• GeometricRelating to the spatial arrangement, shape, and size of geological features or seismic survey configurations...
• Geometrical factorA mathematical function that describes the contribution of different parts of the formation to the total...
• GeophoneA seismic sensor designed to detect ground motion and convert it into an electrical signal. It typically...
• Geophone arrayA spatial arrangement of multiple geophones connected together to act as a single receiver unit. This...
• Geophone cableA multi-conductor cable used in land seismic surveys to connect individual geophones or geophone arrays to...
• Geophone intervalThe distance between individual geophones or geophone arrays along a seismic receiver line. This spacing...
• Geophone offsetThe horizontal distance between a seismic source point and a geophone receiver in a seismic survey. This...
• Geophone patternAn arrangement of multiple geophones connected together and treated as a single receiver unit to improve...
• GeophysicistA scientist who studies the physical properties of the Earth and applies geophysical methods to explore for...
• GeophysicsThe study of the Earth using physical principles and quantitative methods. In the oil and gas industry, it...
• GeopressureSubsurface pore fluid pressure that is abnormally high, exceeding the hydrostatic pressure expected for a...
• Geopressure gradientThe rate at which formation fluid pressure increases with depth. The normal, or hydrostatic, gradient is...
• GeopressuredDescribing a subsurface rock formation where the pore fluid pressure is significantly higher than the normal...
• Geostatic pressureThe pressure exerted by the weight of the overlying rock column at a given depth in the Earth's subsurface...
• Geostatistical methodsA set of statistical techniques used to analyze and predict the spatial or spatiotemporal distribution of...
• Geostatistical modelingThe process of creating three-dimensional models of reservoir properties, such as porosity, permeability, or...
• GeostatisticsA branch of statistics that analyzes and models spatially correlated data, particularly in geological and...
• GeosteerTo direct the trajectory of a directional wellbore in real time based on geological data acquired while...
• GeosteeringThe practice of directing the drill bit in real time to keep the wellbore within a specific geological target...
• Geothermal gradientThe rate at which the Earth's temperature increases with depth below the surface. This gradient is influenced...
• Geronimo lineA safety line or escape rope rigged from the derrick or mast to the ground, providing an emergency exit for...
• GGTThe abbreviation for the Garrett Gas Train, a portable apparatus that measures soluble sulfide and carbonate...
• GhostA spurious reflection in seismic data caused by energy reflecting off the free surface (air-ground or...
• Gibbs' phenomenonThe oscillatory behavior observed in the Fourier series approximation of a discontinuous function near the...
• GIIPThe total volume of natural gas initially present in a reservoir before any production has occurred. This...
• GilsoniteA naturally occurring asphaltic hydrocarbon resin used as a drilling fluid additive to improve shale...
• Gin poleA single, upright mast or pole, often made of steel, used as a temporary lifting device on a well site. It is...
• GlacialDescribing geological features, deposits, or processes related to the action of glaciers or ice sheets...
• Gland bushingA cylindrical component, typically made of brass or a durable polymer, that fits inside a stuffing box to...
• GlauconiteA green, iron-rich phyllosilicate mineral of the mica group, commonly found in marine sedimentary rocks...
• Global Positioning SystemA satellite-based navigation system that provides precise location and time information anywhere on Earth...
• Globe valveA type of valve that regulates fluid flow by moving a disc closer to or further from a seat. The flow path...
• GLRThe ratio of the volume of gas to the volume of liquid produced from a well, typically measured at standard...
• GlycolAn organic compound, typically ethylene glycol or propylene glycol, used as an additive in water-based...
• Glycol absorberA tall, vertical pressure vessel, also called a contactor, used in a glycol dehydration unit to remove water...
• Glycol dehydratorA processing system that removes water vapor from natural gas to meet pipeline quality specifications and...
• GlyphA graphical symbol or icon used to represent multiple data attributes simultaneously in a single visual...
• Goat headA multi-outlet fitting mounted on top of the frac tree or frac stack that joins several high-pressure...
• GOCThe abbreviation for gas-oil contact, which is the interface between free gas and crude oil in a hydrocarbon...
• Goose neckA curved, high-pressure pipe connection on the drilling rig that connects the standpipe to the rotary hose...
• GooseneckA curved section of pipe that connects the standpipe to the rotary hose on a drilling rig. This component...
• GORAn abbreviation for gas/oil ratio, which is the volume of gas produced from a well, measured at standard...
• Government takeThe total revenue collected by a host government from oil and gas operations within its jurisdiction. This...
• GPSAn abbreviation for Global Positioning System, a satellite-based navigation system that provides precise...
• GPTSAn abbreviation for geomagnetic polarity time scale, the dated sequence of reversals of Earth's magnetic...
• GRGamma ray, a type of electromagnetic radiation emitted by naturally radioactive elements present in rocks...
• GrabenA down-dropped block of the Earth's crust bounded by two parallel normal faults. It forms when tensional...
• GradiomanometerA production logging instrument that measures the pressure difference between two vertically separated points...
• Grain densityThe density of the solid mineral material that makes up a rock, excluding any pore space. It is a fundamental...
• GraniteA common type of felsic intrusive igneous rock, characterized by its coarse-grained texture and composition...
• Granular LCMA lost-circulation material made of rigid, irregular particles that bridge and plug the pores or fractures...
• Granular lost-circulation materialA class of lost-circulation material composed of hard, angular or blocky particles, such as nut shell...
• GrappleA downhole tool with hinged, claw-like arms or slips designed to retrieve lost or stuck objects from a...
• Gravel packA sand control method that places a permeable filter medium, typically graded sand or ceramic beads, in the...
• Gravel-pack gunA perforating gun loaded with big-hole charges, usually at a high shot density such as 12 shots per foot, to...
• Gravel-pack logA cased-hole log run to evaluate the integrity and placement of a gravel pack used for sand control. The log...
• Gravel-pack screenA filtering device installed in a wellbore as part of a gravel pack completion, designed to retain the gravel...
• GravimeterAn instrument used to measure minute variations in the Earth's gravitational field. It typically consists of...
• GravimetryThe measurement of the Earth's gravitational field and its variations. This geophysical method is used to...
• GravityThe force of attraction between two bodies, proportional to the product of their masses and inversely...
• Gravity anomalyA localized deviation in the Earth's gravitational field from the expected theoretical value, after...
• Gravity drainageA reservoir drive mechanism where oil flows downwards under the influence of gravity, displacing gas or water...
• Gravity overrideThe tendency of an injected fluid, such as gas or water, to move preferentially through the upper or lower...
• Gravity segregationThe natural separation of fluids with different densities under the influence of gravity. In oil and gas...
• Gravity surveyA geophysical exploration method that measures variations in the Earth's gravitational field across an area...
• Gravity toolfaceThe angular orientation of a directional drilling tool, such as a bent sub or mud motor, relative to the high...
• Gravity unitsA unit of measurement for gravity anomalies, commonly used in gravity surveys to detect subsurface density...
• Gravity-stable displacementA fluid displacement process in a reservoir where the injected fluid is denser than the displaced fluid, or...
• Grease-injection systemA specialized pumping unit that delivers a viscous sealing compound, or grease, into the annular space of a...
• Greasing outThe separation of water-insoluble greasy material, such as an emulsifier, soap or lubricant, from a drilling...
• Greedy algorithmA computational approach that makes the locally optimal choice at each stage of a problem with the hope of...
• Green gasNatural gas that has not yet been processed to remove impurities such as water, hydrogen sulfide, carbon...
• Green listA classification of drilling fluid additives that are considered to have low environmental impact and are...
• GreenfieldAn undeveloped area where oil and gas exploration and production have not previously occurred, lacking any...
• GridA network of regularly spaced points or lines used to organize spatial data for acquisition, processing, or...
• GriddingThe process of dividing a continuous spatial domain such as a reservoir into a discrete set of cells or...
• Gridding algorithmA computational procedure used to create a grid or mesh that discretizes a continuous geological domain into...
• GrindTo reduce the particle size of solid materials, such as weighting agents or lost circulation materials...
• Gripper blocksShaped metal blocks mounted on the two opposing chains of a coiled tubing injector head, which clamp the...
• Gross productionThe total volume of oil, gas, or water produced from a well or field before any deductions for royalty...
• Ground rollA type of high-amplitude, low-frequency coherent noise that propagates along the surface during land seismic...
• GroundwaterWater held underground in the soil or in the pores and crevices of rock, occupying the zone of saturation. In...
• GroupA collection of individual geophones or hydrophones connected together to form a single receiver station in a...
• Group intervalThe physical distance between the centers of adjacent receiver groups in a seismic survey spread. This...
• Group velocityThe velocity at which the envelope of a wave packet or a group of waves propagates through a medium. In...
• Growth faultA syndepositional normal fault that forms concurrently with sedimentation, where the thickness of sedimentary...
• Guar gumA natural polysaccharide derived from the guar bean, used as a viscosifier and fluid loss control agent in...
• Guard electrodeAn electrode on a resistivity logging tool that emits a focusing current to constrain the path of the primary...
• Guard logA type of focused resistivity log that uses guard electrodes to force the measuring current to flow...
• GuardrailsA set of programmable rules, constraints, and filters designed to control the behavior and output of an...
• Guided waveA seismic wave that propagates within a specific layer or waveguide in the Earth, where its energy is trapped...
• GumboA sticky, hydrated clay formation encountered during drilling that can adhere to drill bits and other...
• GunA seismic source device used to generate acoustic energy for marine seismic surveys. Air guns release...
• Gun barrelA tall, vertical tank used for the gravity separation of oil, water, and gas, often as a final stage of water...
• Gun clearanceThe distance between the outer wall of a perforating gun and the inner wall of the casing or liner it is...
• Gun the pitsTo agitate the drilling fluid in mud pits or tanks using high-pressure jets of mud pumped through nozzles...
• Gun zeroThe reference point on a perforating gun string from which all perforating depths are measured. This point is...
• GunkA viscous, semi-solid material that forms in oil and gas wells, often composed of paraffin, asphaltenes, or...
• Gunk plugA viscous, semi-solid mixture of bentonite clay and diesel or crude oil, sometimes with cement, used to seal...
• Gunk squeezeA remedial operation involving pumping a gunk plug, a viscous mixture of bentonite and diesel or crude oil...
• GWCThe depth in a reservoir below which pores are filled with water and above which they hold gas, marking the...
• Gyp mudA type of water-based drilling fluid that uses gypsum (calcium sulfate) as a primary additive to control clay...
• GypsumA soft sulfate mineral composed of hydrous calcium sulfate (CaSO4·2H2O), often found in evaporite deposits...

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