A string of casing used to shut off all water above an oil sand. It is often necessary to run more than one string before a […]

The underground level at which water is found. This term is often used in connection with underground water supplies used for irrigation and industrial plants. Term […]

Shortened form of boll weevil. See boll weevil.

An instrument near the driller’s position on a drilling rig that shows both the weight of the drill stem that is hanging from the hook (hook […]

A material that has a high specific gravity and is used to increase the density of drilling fluids or cement slurries.

1) the activities and methods of preparing a well for the production of oil and gas or for other purposes, such as injection. 2) the method […]

The recording of information about subsurface geologic formations, including records kept by the driller and records of mud and cutting analyses, core analysis, drill stem tests, […]

Any of several operations used to increase the production of a well, such as acidizing or fracturing. See acidize, formation fracturing.

A borehole; the hole drilled by the bit. A wellbore may have casing in it or it may be open (uncased); or part of it may […]

The equipment installed at the surface of the wellbore. A wellhead includes such equipment as the casing head and tubing head. adj pertaining to the wellhead […]

A long steel casing that uses an inclined plane to cause the bit to deflect from the original borehole at a slight angle. Whipstock are sometimes […]

1) a well drilled in an area where no oil or gas production exists. 2) [nautical] the geared sheave of a windlass used to pull anchor […]