Oil & Gas Terms in Category G

Gauge joint

The heaviest-wall casing section of the string, usually located just below the preventers or tree.

Gunk plug

A slurry in crude or diesel oil containing any of the following materials or combinations: bentonite, cement, attapulgite, and guar gum (never with cement).

Used primarily in combating lost circulation.

Gas flare

A permanent flame, sometimes located at the top of a stack, for disposing of combustible gas produced from refining or chemical process, as in a petroleum refinery or oil rig.


Gas / oil ratio.

May refer to a solution gor or total gor.

Gas injection

The technique of injecting gas into a reservoir.

It may be done for pressure maintenance, oil viscosity reduction, light end stripping or storage.

see injection gas.

Guy wire

A rope or cable used to steady a mast or pole.


A naturally occurring crystalline form of calcium sulfate in which each molecule of calcium sulfate is combined with two molecules of water.

See calcium sulfate.

Gunk slurry

A slang term to denote a mixture of diesel oil and bentonite.


To create holes in casing and cement set through a productive formation.

A common method of completing a well is to set casing through the oil-bearing formation and cement it.

A perforating gun is then lowered into the hole and fired to detonate high-powered jets or shoot steel projectiles (bullets) through the casing and cement and into the pay zone.

The formation fluids flow out of the reservoir through the perforations and into the wellbore.

See perforating gun.

Gun the pits

To agitate the drilling fluid in a pit by means of a mud gun, electric mixer, or agitator.


An oilwell that has come in with such great pressure that the oil jets out of the well like a geyser.

In reality, a gusher is a blowout and is extremely wasteful of reservoir fluids and drive energy.

In the early days of the oil industry, gushers were common and many times were the only indication that a large reservoir of oil and gas had been struck.

See blowout.


Any hydrophilic plant polysaccharides or their derivatives that, when dispersed in water, swell to produce a viscous dispersion or solution.

Unlike resins, they are soluble in water and insoluble in alcohol.

Gravity survey

An exploration method in which an instrument that measures the intensity of the earth’s gravity is passed over the surface or through the water.

In places where the instrument detects stronger or weaker than normal gravity forces, a geologic structure containing hydrocarbons may exist.

Gravity – api

The specific gravity or density of oil expressed in terms of a scale devised by the american petroleum institute.

The lighter the oil, the greater the gravity; other factors being equal, the higher the api gravity, the better price the oil will bring.

Gravity – specific

Density expressed as the ratio of the weight of a volume of substance to the weight of an equal volume of another standard substance.

In the case of liquids and solids, the standard is water.

In the case of natural gas or other gas materials, the standard is air.