A well which produces fluids (gas, oil or water).

Oil and gas which has not been produced but has been located and is recoverable.

This is crude oil direct from the wellbore, before it is treated in a gas separation plant.

This is gas that is produced from the well, unprocessed natural gas or the inlet natural gas to a plant. The raw gas still contains natural gas liquidswater and some other impurities. The raw gas must be processed in a gas processing plant to make it ready to be sold. 

That proportion of the oil and/gas in a reservoir that can be removed using currently available techniques.

The ratio of recoverable oil and/or gas reserves to the estimated oil and/or gas in place in the reservoir.

Residual gas that remains in the drilling fluid despite being circulated to the surface. At the surface, it remains in the mudstream, which is suctioned from the mud pit and recirculated into the wellbore.

The underground formation where oil and gas has accumulated. It consists of a porous rock to hold the oil or gas, and a cap rock that prevents its escape.

Oil that does not move when fluids are flowed through the rock in normal conditions, for example primary and secondary recovery, and invasion.

Natural gas containing heavier hydrocarbons than a lean gas. Its liquid content adds important economic value to developments containing this type of fluid.

Lean oil that has absorbed heavier hydrocarbon components from a gas stream.

A rig is the machine used to drill a wellbore. A rig is either structured on land or sea for it to access oil from the ground. 

This describes the recovery of oil or gas from a reservoir by artificially maintaining or enhancing the reservoir pressure by injecting gas, water or other substances into the reservoir rock.

This describes the process of separating liquid and gas hydrocarbons and water. This is typically accomplished in a pressure vessel at the surface, but newer technologies allow separation to occur in the wellbore under certain conditions.

This describes the gas that remains after its separation from condensate.