Oil and Gas Terms Beginning with “G”

What Is GGT? GGT is the universal abbreviation for the Garrett Gas Train, a portable three-chamber rig-site instrument that quantifies hydrogen sulfide and carbonate concentrations in drilling fluids by acidifying a mud… Read more →

Abbreviation for gas/liquid ratio, the ratio of produced gas to produced liquids (oil and water). Read more →

Abbreviation for gas/oil ratio, the ratio of produced gas to produced oil. Read more →

GPS (Global Positioning System) in oilfield applications refers to the use of satellite-based positioning technology to accurately determine the geographic coordinates of wells, seismic survey equipment, offshore… Read more →

GPTS stands for Geomagnetic Polarity Time Scale, the chronological reference framework cataloguing every known reversal of Earth's magnetic field polarity back through geological time, expressed as a numbered sequence… Read more →

An abbreviation for gamma ray, usually with reference to the gamma ray log. Read more →

The unit of acceleration commonly used in gravity surveying. 1 Gal (1000 milliGal or 106 microGal) = 1 cm/sec/sec. Read more →

What Is the Garrett Gas Train? The Garrett Gas Train (GGT) is a portable field instrument that quantifies hydrogen sulfide (H2S) and carbonate concentrations in drilling fluids by acidifying a mud sample inside a sealed… Read more →

Gaussian collocated cosimulation is a sequential Gaussian simulation algorithm that incorporates secondary data (such as seismic attributes) at every simulation grid node by exploiting a Markov-type screening hypothesis… Read more →

Gaussian techniques in geostatistics and reservoir characterization are a family of parametric stochastic simulation methods that model the spatial distribution of reservoir properties (porosity, permeability,… Read more →

The ringing near a discontinuity in a signal that is caused by incomplete Fourier synthesis, or missing frequencies. Read more →

The Global Positioning System (GPS) is a satellite-based navigation network operated by the United States Space Force that provides precise location data (latitude, longitude, and elevation) to any receiver with an… Read more →

The change in the amplitude of an electrical signal from the original input to the amplified output. Read more →

Galena is the natural mineral form of lead sulfide, with the chemical formula PbS. It is the world's most important ore for lead production, mined in major deposits in Australia (Mount Isa, Broken Hill, Cannington), the… Read more →

Galvanic anodes are blocks or rods of an electrochemically active metal (typically zinc, aluminum, or magnesium) that are connected electrically to a steel structure and corrode preferentially, delivering cathodic… Read more →

(noun) An instrument that measures fluid density by directing a beam of gamma radiation through a pipe or vessel and detecting the attenuated signal on the opposite side. The degree of attenuation is proportional to the… Read more →

Gamma ray interactions in formation evaluation are the physical processes by which gamma ray photons transfer energy to matter (typically to electrons in atoms) as the photons pass through formation rocks and pore… Read more →

What Is a Gamma Ray Log? A gamma ray log records the natural radioactivity of subsurface formations as a wireline tool or LWD sensor traverses the wellbore, expressing measurements in API units to distinguish clay-rich… Read more →

A gamma-gamma log is a borehole measurement that uses an artificial source of gamma rays and a detector of gamma rays to determine the bulk density of the formation. The name is the older term for what the industry… Read more →

A gas anchor is a downhole device installed in the pump intake section of a sucker rod pumping (beam pump) installation to separate free gas from the produced liquid before it enters the pump barrel, preventing gas lock… Read more →

A gas buster in drilling operations is a vessel or device installed in the mud return line between the choke manifold and the mud pits to separate free gas from drilling fluid returning to surface during a well control… Read more →

What Is a Gas Cap? A gas cap is a volume of free gas that accumulates in the highest portion of a hydrocarbon reservoir, sitting above the oil column due to its lower density. Gas caps form when the reservoir pressure… Read more →

What Is Gas Cap Drive? Gas cap drive (also called gas-cap expansion drive) is a natural reservoir drive mechanism in which dissolved and free gas expanding from an initial gas cap above the oil zone provides the primary… Read more →

A gas chimney is a vertical or near-vertical zone of subsurface gas leakage extending upward from a poorly sealed hydrocarbon accumulation, where free gas (and sometimes light condensate or aqueous methane in solution)… Read more →

What Is Gas Condensate? Gas condensate is a mixture of light hydrocarbons — predominantly methane with significant proportions of ethane, propane, butanes, and heavier components (C5+ pentanes and above) — that exists… Read more →

(noun) A production phenomenon in which gas from a gas cap migrates downward into the oil-producing perforations due to the pressure drawdown created by production, forming a cone-shaped intrusion of gas around the… Read more →

What Is Gas Cut Mud? Gas cut mud is a condition in which free gas from the drilled formation enters the drilling fluid in the borehole annulus and becomes dispersed throughout the mud as small bubbles, reducing the… Read more →

The gas deviation factor, written z and also called the z-factor, compressibility factor, or supercompressibility factor, is the dimensionless correction that turns the ideal gas law into a usable description of real… Read more →

Gas drive is a primary recovery mechanism in which the energy stored in expanding gas pushes oil out of the reservoir rock and into the wellbore, requiring no injected fluid or external energy beyond the natural… Read more →

What Is the Gas Formation Volume Factor? Gas formation volume factor (symbol Bg) is a dimensionless ratio that relates the volume occupied by a quantity of natural gas at reservoir pressure and temperature to the volume… Read more →