Gas Cap
In a field where oil is saturated with gas, so that it can dissolve no more, some gas will collect at the top of the reservoir, where it is known as cap gas, and forms a gas cap. Cap Gas overlies the oil and thus provides additional pressure for oil production, but will therefore often be produced only after all the oil has been produced and will then be treated as Non Associated Gas. Unlike Solution Gas, it is not commingled with the oil.