Associated petroleum gas (APG) is a mixture of hydrocarbon gases, dissolved in oil or residing in "caps" of oil and gas condensate fields.
The APG is extracted from the trolly oil flow due to pressure relief, basically it is a mixture of hydrocarbons (from methane to hexane) with non-hydrocarbon components: hydrogen sulphide, nitrogen, mercaptanes which later on present challenges in processing of the gas.
The APG is a highly valuable feed for energy and chemical industries.