What is the petroleum industry term for crude oil and natural gas found in the same reservoir?

Associated petroleum gas is the petroleum industry term for crude oil and natural gas found in the same reservoir.

This gas may be dissolved in the crude oil under reservoir pressure or exist as a separate gas cap above the oil. When a field produces oil, pressure changes can release the gas, making it an important part of production planning and surface processing.

Operators may sell associated gas through pipelines, use it as fuel, reinject it to maintain reservoir pressure, or liquefy and transport it. Where infrastructure is unavailable, some historically burned it in flares. Flaring wastes energy and releases carbon dioxide, so reducing routine flaring has become a major industry and environmental objective.

Associated petroleum gas differs from non-associated gas, which comes primarily from reservoirs containing gas rather than significant crude oil. The term also should not be confused with liquefied petroleum gas, a group of light hydrocarbons such as propane and butane produced during natural-gas processing or refining.