Natural gas is formed from ancient organic materials such as animals and plants.

When these animals and plants died millions of years ago, they were buried under many layers of silt and other organic remains. Over time, these organic materials underwent slow and complex chemical reactions, and were gradually transformed into natural gas resting on liquefied petroleum deposits. Therefore, natural gas can often be obtained in the course of recovering petroleum.

Ancient animals died millions of years ago and gradually transformed into natural gas after undergoing complex chemical reactions.