Natural gas is commonly found near deposits of oil as it is created by a process that combines high temperature and compression that breaks down organic matter. Natural gas deposits are generally trapped inside sedimentary basins which serve as a reservoir that can be accessed through a drilling process.
Natural gas can also be created by microoganisms that are found inside the intestines of humans and animals. These organisms break down decomposing matter inside the intestine to create methane. Natural gas that is created due to high temperatures and pressure is called thermogenic methane. Methane created inside animals and humans is referred to as biogenic methane.