Natural gas Natural gas Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium. It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years. The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas. Natural gas is a fossil fuel used as a source of energy for heating,
Natural-gas processing of three types of wells: crude oil wells, gas wells, and condensate wells. Natural gas that comes from crude oil wells is typically called "associated gas". This gas can have existed as a gas cap above the crude oil in the underground formation, or could have been dissolved in the crude oil. Natural gas from gas wells and from condensate wells, in which there is little or no crude oil, is called "non-associated gas". Gas wells typically produce only raw natural gas, while condensate wells produce raw natural gas along with other low molecular weight hydrocarbons. Those that are liquid