A term sometimes used to refer to those industry activities that fall between exploration and production (upstream) and refining and marketing (downstream). The term is most often applied to pipeline transportation of crude oil and natural gas.

A solid and naturally occurring inorganic substance. Minerals are distinguished from one another by careful observation or measurement of physical properties such as density, crystal form and hardness.

MODU stands for Mobile Offshore Drilling Unit. The term is used to categorise self-contained floatable drilling machines.

This measures the fluid pressure and collects small samples in a well.

A term that is generally synonymous with drilling fluid and that encompasses most fluids used in hydrocarbon drilling operations, especially fluids that contain significant amounts of suspended solids, emulsified water or oil. Mud includes all types of water-base, oil-base and synthetic-base drilling fluids.