Associated gas, also called associated petroleum gas, solution gas, wet gas, gas-cap gas, flair gas, or field gas, is the natural gas that exists in direct association with crude oil deposits within a petroleum reservoir. It occurs either as free gas forming a gas cap above the oil column or as gas dissolved in the liquid petroleum under reservoir pressure and temperature conditions. This gas is liberated and produced concurrently with the crude oil during extraction operations from oil wells, distinguishing it fundamentally from other forms of natural gas.
Associated gas is separated from the produced oil at the wellhead or surface facilities through a series of separators that reduce pressure, allowing the dissolved gas to come out of solution and the free gas to be captured separately. This separation process is essential because the gas must be handled independently from the oil stream to meet pipeline specifications, storage requirements, or further processing needs. Associated gas is contrasted with non-associated gas, which is natural gas produced from dedicated gas reservoirs or wells that yield little to no crude oil.
Associated gas typically consists of lighter hydrocarbons such as methane along with varying amounts of ethane, propane, and heavier components, though its exact composition depends on the specific reservoir conditions.
