Oil & Gas Terms in Category W



In mud terminology, refers to the density of a drilling fluid.


Of a measurement, expresses degree of confidence in result of measurement of a certain quantity compared with result of another measurement of the same quantity.



A method of improved recovery in which water is injected into a reservoir to remove additional quantities of oil that have been left behind after primary recovery.

Waterflooding usually involves the injection of water through wells specially set up for water injection and the removal of water and oil from production wells drilled adjacent to the injection wells.


A secondary recovery mechanism which involves the injection of water into the reservoir through injector well(s) to maintain reservoir pressure and drive the oil towards the producing well(s).


A long steel casing that uses an inclined plane to cause the bit to deflect from the original borehole at a slight angle.

Whipstocks are sometimes used in controlled directional drilling, in straightening crooked boreholes, and in sidetracking to avoid unretrieved fish.


Abbreviation: waiting-on-cement

Washover shoe

A device employed to protect seals, seating nipples, etc., during mill-out operations.

Wireline survey

A general term often used to refer to any type of log being run in a well.

See log.

Wireline entry guide

A flared-end sub run on the end of the tubing string to permit easy access of wireline tools into the tubing id.

Water coning

The upward encroachment of water into a well caused by pressure drawdown from production.

Well servicing

The maintenance work performed on an oil or gas well to improve or maintain the production from a formation already producing.

It usually involves repairs to the pump, rods, gas lift valves, tubing, packers, and so forth


Mechanical tongs; sometimes used generically for all brands of tongs.

Wall cake

Also called filter cake or mud cake.

See filter cake.

Wet oil

Oil with a water content above specification.


The horizontal valving on a tree.

Wiper plug

A rubber-bodied, plastic- or aluminum-cored device used to separate cement and drilling fluid as they are being pumped down the inside of the casing during cementing operations.

A wiper plug also removes drilling mud that adheres to the inside of the casing.

Wild well

A well that has blown out of control and from which oil, water, or gas is escaping with great force to the surface.

Also called a gusher.