Oil, one of the main objects of geological exploration, is a viscous, dark brown liquid, known as the "blood of industry". There are oil reserves in parts of the upper crust. The main components are mixtures of various alkanes, cycloalkanes and aromatic hydrocarbons. The oil formation mechanism of petroleum has two kinds of theories: biological sedimentation to oil and petrochemical oil. The former is widely accepted. It is believed that petroleum is formed by organisms in ancient oceans or lakes after a long evolution, which belongs to biological sedimentation to oil and is non renewable; The latter believes that oil is generated from the carbon in the earth's crust, which has nothing to do with biology and is renewable. Petroleum is mainly used as fuel and gasoline, and is also the raw material of many chemical industrial products, such as solutions, fertilizers, pesticides and plastics