The
composition of raw natural gas depends on a series of natural
factors that determine its formation process and the conditions
under which it accumulated in its original deposit.
Like petroleum, natural gas is found in underground deposits
in many parts of the planet, both on land and at sea, and a
considerable number of deposits contain natural gas associated
with petroleum. In these cases, the gas is known as associated
natural gas. When a deposit contains little or no oil,
the natural gas is called nonassociated