Natural gas paleontological remains deposited underground for a long time. Gaseous hydrocarbons produced by slow transformation and metamorphism are inflammable and often accompany oil field oil production. Natural gas is stored in underground multi-pore rock formations. The main component is methane, with a specific gravity of 0.65. It is lighter than air and has colorless, odorless and non-toxic characteristics. Gas companies add the odorant (tetrahydrothiophene) in accordance with government regulations to allow users to smell. If the concentration of natural gas in the air is within the range of 5% ~ 15%, the explosion can occur in the case of open fire. This concentration range is the explosion limit of natural gas. The explosion produces high pressure and high temperature in an instant, which is very destructive and dangerous. According to the state of natural gas storage, it can be divided into structural natural gas, water-soluble natural gas and coal natural gas. The structural natural gas can be divided into wet natural gas with crude oil production and dry natural gas without liquid component.