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
Natural-gas condensate or reused in some fashion. Some of the raw natural gas may be re-injected into the producing formation to help maintain the reservoir pressure, or for storage pending later installation of a pipeline. Drip gas, so named because it can be drawn off the bottom of small chambers (called "drips") sometimes installed in pipelines from gas wells, is another name for natural-gas condensate, a naturally occurring form of gasoline obtained as a byproduct of natural gas extraction. It is also known as "condensate", "natural gasoline", "casing head gas", "raw gas", "white gas" and "liquid gold". Drip gas is defined in