Natural-gas processing at ambient conditions (i.e., pentane and heavier) are called "natural-gas condensate" (sometimes also called "natural gasoline" or simply "condensate"). Natural gas is called "sweet gas" when relatively free of hydrogen sulfide; gas that does contain hydrogen sulfide is called "sour gas". Natural gas, or any other gas mixture, containing significant quantities of hydrogen sulfide, carbon dioxide or similar acidic gases, is called "acid gas." Raw natural gas can also come from methane deposits in the pores of coal seams, and especially in a more concentrated state of adsorption onto the surface of the coal itself. Such gas is referred to
Billion cubic metres of natural gas standard, the gas volume is measured at . That means that 1 billion cubic metres of natural gas by the International Energy Agency standard is equivalent to 1.017 billion cubic metres of natural gas by the Russian standard. Some other organizations use an energy equivalent-based standards. BP uses a standard which is equivalent to per billion cubic metres. Cedigaz uses a standard which is equivalent to per billion cubic metres. Billion cubic metres of natural gas Billion cubic metres of natural gas (abbreviated: bcm) is a measure of natural gas production and trade. Depending of implied standards, this measure may