Oil & Gas Terms in Category G

Grind out

See shake out

Grease injector

A surface device used in pressure control for slickline.

Grass gooser

A hoe or other kind of weed cutter.

Guide ring

A cylindrical metal ring used to guide packers past casing obtrusions.


Any relatively sticky formation (such as clay) encountered in drilling


A device for measuring and recording the specific gravity of a gas or liquid passing a point of measurement.

Gravel packing

A method of well completion in which a slotted or perforated liner, often wire-wrapped, is placed in the well and surrounded by gravel.

If open hole, the well is sometimes enlarged by underreaming at the point where the gravel is packed.

The mass of gravel excludes sand from the wellbore but allows continued production.

Gravel-pack packer

A packer used for the well completion method of gravel packing.



A device that is inserted into a pipeline for the purpose of cleaning; a line scraper.

Also called a pig.


A device that is lowered into the borehole of a well for various purposes such as enclosing surveying instruments, detonating instruments, and the like.


Injection of nitrogen for gas lift valving.

Gas lock


A condition sometimes encountered in a pumping well when dissolved gas, released from solution during the upstroke of the plunger, appears as free gas between the valves.

If the gas pressure is sufficient, the standing valve is locked shut, and no fluid enter the tubing.


A device fitted to the gauging hatch on a pressure tank that enables manual dipping and sampling without loss of vapor.


Gamma-ray-neutron (a well log).


A mechanism that is fitted into an overshot to grasp and retrieve fish from the borehole.

The interior of a grapple is wickered to engage the fish.

Gel strength

A measure of the ability of a colloidal dispersion to develop and retain a gel form, based on its resistance to shear.

The gel, or shear, strength of a drilling mud determines its ability to hold solids in suspension.

Sometimes bentonite and other colloidal clays are added to drilling fluid to increase its gel strength.


The curved connection between the rotary hose and the swivel.