Oil and Gas Terms Beginning with “G” — Page 5

What Is a Gravel Pack Screen? Gravel pack screen (also called a sand screen or downhole screen ) is a tubular filtration device installed inside the production casing or open hole across a producing interval that… Read more →

A gravimeter is an instrument that measures the acceleration due to gravity, or more usefully, the tiny variations in the gravitational field from one point to another caused by differences in the density of the rock… Read more →

The measurement of gravity or the study of its variations. Read more →

Gravity in the oil and gas industry refers to several interconnected concepts including: API gravity, the petroleum industry's standard measure of crude oil density expressed on the American Petroleum Institute's… Read more →

A gravity anomaly is the difference between the observed gravitational acceleration measured at a survey point and the theoretical gravity value predicted for the same point on a reference ellipsoid model of the Earth,… Read more →

What Is Gravity Drainage? Gravity drainage (also called gravitational drainage or gas-cap gravity drainage ) is a reservoir drive mechanism in which oil drains downward through the reservoir rock under gravitational… Read more →

Gravity override is the preferential upward migration of an injected fluid in a reservoir due to the density contrast between the injected fluid and the native reservoir fluids, causing the injection fluid to override… Read more →

Gravity segregation in petroleum engineering is the tendency of fluids with different densities to stratify into distinct horizontal layers when the gravitational force exceeds the mixing forces (viscous drag,… Read more →

What Is a Gravity Survey? Gravity survey (also called a gravimetric survey or gravity geophysical survey ) is a geophysical exploration method that measures lateral variations in the Earth's gravitational field caused… Read more →

One-tenth of a milliGal: (10 g.u. = 1.0 mGal). Gravity units are sometimes used in old gravity maps. Read more →

A frontal advance in which gravity and viscous forces are in equilibrium, resulting in a stable, highly efficient frontal advance. Read more →

A grease injection system is a wellhead pressure-control assembly used during braided-line, electric-line, or wireline operations to contain wellhead fluids and pressure while allowing the wireline to enter and exit the… Read more →

Greasing out is a drilling fluid contamination phenomenon in which the lubricating compounds or oil-based additives in a water-based drilling mud separate from the aqueous phase and rise to form a floating grease or oil… Read more →

A greedy algorithm is a problem-solving procedure that builds a solution one step at a time, always choosing the option that looks best at that moment without revisiting earlier choices, on the assumption that a… Read more →

Green gas is the raw, untreated natural gas stream as it first leaves the wellhead, before any conditioning, sweetening, or dehydration has taken place. In oilfield usage the word "green" carries its older sense of… Read more →

To convert irregularly spaced points to a regular spacing by interpolation. Read more →

Gridding in petroleum geoscience and reservoir engineering is the process of creating a spatial mathematical framework — a structured or unstructured grid of nodes, cells, or elements — that discretizes a continuous… Read more →

A gridding algorithm in petroleum geoscience and reservoir engineering is a computational procedure that assigns numerical values (porosity, depth, thickness, saturation, seismic amplitude, or any other spatial… Read more →

The fineness to which cement is ground. Grind also may refer to a specific production of cement, such as the lot number. Read more →

Gripper blocks in oil and gas well service equipment are mechanical gripping elements that clamp onto pipe, tubing, or wireline to transmit tensile or compressive loads, hold position, or provide the reaction force… Read more →

The total production of oil, gas or water from a well or field over a specific period of time. Read more →

Ground roll in land seismic acquisition is the coherent, low-frequency, high-amplitude surface wave noise generated at the shot point and propagating along the Earth's surface as a Rayleigh wave, which contaminates… Read more →

Groundwater is the water held in the subsurface below the water table, occupying the pores, fractures, and intergranular spaces of rocks and unconsolidated sediments. It is not an underground lake but water saturating a… Read more →

A set of seismometers whose output is sent to a common data channel to record a seismic trace. A large group is known as a patch. Read more →

The distance between geophones or groups of geophones. Read more →

What Is a Growth Fault? Growth fault (also called a syn-sedimentary fault or contemporaneous fault) is a normal fault that was active during sediment deposition, causing sedimentary layers to accumulate thicker on the… Read more →

Guar gum is a naturally occurring galactomannan polysaccharide extracted from the endosperm of the guar plant (Cyamopsis tetragonoloba, a legume cultivated primarily in India and Pakistan) that is the dominant… Read more →

A guard electrode is a focusing electrode in an electrical resistivity logging tool that is designed to confine the measurement current to a defined horizontal beam that penetrates radially into the formation,… Read more →

A guard log in wireline formation evaluation is a type of focused resistivity log that uses a lateral guard electrode system to direct the measurement current radially into the formation rather than allowing it to… Read more →

A guide shoe (also called a casing shoe or float shoe) is a short, rounded or tapered steel and cement accessory threaded onto the bottom joint of a casing string before it is run into a wellbore, designed to guide the… Read more →