Oil and Gas Terms Beginning with “G” — Page 4

What Is Geopressure? Geopressure (also called abnormal pressure, overpressure, or subnormal pressure in its opposite form) is any formation pore pressure that deviates significantly from the normal hydrostatic gradient… Read more →

The geopressure gradient is the rate of change of formation pore pressure with depth in the subsurface, typically expressed in units of pounds per square inch per foot (psi/ft), pounds per gallon (ppg) equivalent mud… Read more →

The pressure of the weight of overburden, or overlying rock, on a formation; also called lithostatic pressure. Read more →

Geostatistical methods in petroleum reservoir characterization are a family of mathematical and statistical techniques that quantify, model, and reproduce the spatial correlation structure of subsurface rock and fluid… Read more →

Geostatistical modeling in petroleum engineering is the process of constructing quantitative three-dimensional representations of subsurface reservoir properties — including porosity, permeability, net-to-gross ratio,… Read more →

What Is Geostatistics? Geostatistics (also called spatial statistics or stochastic reservoir modeling) is a branch of statistics adapted for data that exhibits spatial correlation — meaning that nearby measurements tend… Read more →

What Is Geosteering? Geosteering (also called geological steering or formation-guided drilling) is the real-time process of adjusting a horizontal or directional wellbore trajectory while drilling, using geological and… Read more →

What Is the Geothermal Gradient? Geothermal gradient (also called the thermal gradient or temperature gradient) is the rate at which temperature increases with depth below the earth's surface, typically expressed in… Read more →

A ghost in marine seismic acquisition is a short-path multiple reflection generated when upward-traveling seismic energy from a source or receiver reflects off the sea surface (a nearly perfect acoustic reflector with a… Read more →

A trademarked product of American Gilsonite Co. Read more →

A gin pole is a simple lifting device made of a long pipe or beam tilted at an angle, with a pulley at the top and a winch or hoist at the base. It is used in oilfield operations to lift loads vertically when a full… Read more →

Pertaining to the environment of deposition by glaciers. Read more →

Glauconite is a green, iron-bearing potassium mica mineral (formula approximately K(Fe,Al,Mg)2(Si,Al)4O10(OH)2) that forms in marine sedimentary environments under specific geochemical conditions at or just below the… Read more →

Glycol is the common name for a family of dihydric alcohols, organic compounds that each carry two hydroxyl (OH) groups, described by the general formula C2nH4n+2On+1. The simplest and most economically important member… Read more →

In a glycoldehydrator unit, the cylinder composed of various perforated trays in which wet gas and glycol are put in contact. Read more →

A glycol dehydrator is a gas processing unit that removes water vapor from natural gas by contacting the wet gas with a lean (water-lean) solution of triethylene glycol (TEG) or diethylene glycol (DEG) in an absorption… Read more →

A glyph in petroleum geoscience and petrophysical visualization is a graphical symbol or geometric icon used to represent multiple data attributes simultaneously at a single spatial location on a map, cross-section, or… Read more →

In drilling operations, a gooseneck (also spelled goose neck) is the curved pipe connection at the top of the standpipe on the drilling derrick that transitions the high-pressure drilling mud flow from the vertical… Read more →

In drilling operations, a gooseneck (also spelled goose neck) is the curved pipe connection at the top of the standpipe on the drilling derrick that transitions the high-pressure drilling mud flow from the vertical… Read more →

What Is Government Take? Government take (also called state take or fiscal take ) is the total share of petroleum revenues and profits captured by a host government through its fiscal system, encompassing royalties,… Read more →

A graben is a depressed crustal block that has subsided relative to the adjacent rocks on either side, bounded by inward-dipping normal faults on two or more sides, forming an elongated trough or basin in which… Read more →

What Is a Gradiomanometer? A gradiomanometer is a production logging tool that measures fluid density in a producing wellbore by detecting the differential pressure between two sensors separated by a fixed vertical… Read more →

Grain density is the density of the solid (grain) component of a formation rock or core sample, excluding the pore-fluid contribution that affects the bulk rock density — providing the fundamental rock matrix density… Read more →

Granite is a coarse-grained, intrusive (plutonic) igneous rock of felsic composition, dominated by interlocking crystals of quartz (typically 20% to 35%), alkali feldspar and plagioclase feldspar (45% to 70% combined),… Read more →

Granular lost circulation material (granular LCM) in drilling engineering is a solid particulate additive mixed into drilling mud or pumped as a concentrated pill to cure or prevent the uncontrolled loss of drilling… Read more →

Granular lost-circulation material in the context of drilling fluid engineering refers specifically to the particle-type subcategory of lost circulation treatment additives — comprising coarse, rigid, irregularly shaped… Read more →

A generic name given to tools that engage on the outer surface of a tubing string or tool assembly, generally for fishing purposes. Read more →

What Is a Gravel Pack? A gravel pack is a sand control completion technique in which a layer of precisely sized gravel — typically 16/20 or 20/40 mesh (0.4–1.2 mm) Ottawa or Brady sand — is placed between a production… Read more →

A gravel-pack gun is a specialized perforating gun system designed to create the large-diameter, high-density perforations required for effective gravel pack completions in unconsolidated or weakly consolidated… Read more →

What Is a Gravel-Pack Log? A gravel-pack log is a cased-hole nuclear wireline measurement, typically a gamma ray or neutron log, run before and after gravel packing a sand-control completion to evaluate the placement… Read more →