Natural gas is a fossil fuel composed of flammable gases, primarily methane, that formed from decaying organisms buried deep beneath the Earth's surface due to intense heat and pressure over thousands of years. It is one of the major energy sources throughout the United States and the world.
Natural gas is often found with oil, since they are both formed by the same organic matter. The usual method for extracting oil and natural gas is by drilling in an appropriate area. As the heat and pressure increase, the concentration of gas increases, so deeper deposits probably contain more gas.
Biogenic natural gas is created by methanogenic bacteria that consume carbon dioxide and produce methane. Although biogenic gas contains slightly less methane than regular natural gas, it is a renewable resource, while regular natural gas is not.