Oil and Gas - Terminology

Following is a list of some common terms and definitions used in the oil and gas industry

Associated gas

Gas produced from reservoirs where gas is dissolved in crude oil.

Cassion

An open-bottomed pipe usually of large diameter, projecting vertically down into the sea. May be used for clean or oily water disposal or for firewater/cooling water lift.

Choke

Special control valve for throttling a high pressure fluid to a lower pressure for production.

Christmas Tree

Top of the well, includes provisions for well overhaul and wing valves. Often termed the wellhead.

Flowlines

Lines from christmas tree to the inlet manifold.

Heavy Crude

Crude oil with a viscosity above 1000 mPas at ambient temperature or a specific gravity above 900 kg/m³.

Jacket

Steel structure for supporting the processing facilities for an offshore platform.

Light Crude

Crude with a viscosity below 1000 mPas at ambient conditions or a specific gravity below 900 kg/m³.

Lift gas

Gas injected at the wellhead in order to reduce the static head downhole and thus increase oil production of that well.

Normal m³ gas

One Cubic meter gas at normal conditions i.e. 0°C and 1 atm.

Standard m³ gas

One cubic meter gas at standard conditions 15°C and 1 atm.

Topsides

All the surface facilities on a platform. Includes processing facilities, utilities, living quarters, essential services, wellhead and drilling facilities and flare stack.

Tubing

Pipe used to contain and convey reservoir fluid from the reservoir to the wellhead.

Water cut

Water production as percentage of gross production.

Well Completion

A well completion consists of the operations necessary to cause the well to produce, following the installation and cementing of the casing. The term "well completion" is also used to refer to the equipment utilized, rather than the operation itself.