Petroleum is a mixture of hydrocarbons. The theory of inorganic generation holds that carbon and hydrogen are inherent in the universe, or come directly or indirectly from magma. The organic generation theory holds that oil and natural gas are generated from organic matter dispersed in sedimentary rocks in various geological historical periods. The so-called organic matter includes the remains of living things, as well as the excretions and secretions of living things in the process of maintaining life. All organic matter comes from biological sources.

Although there are more than 1.5 million species of creatures on the earth, including animals and plants, marine creatures and terrestrial creatures, lower creatures and higher creatures, living creatures and dead creatures. , they are all composed of the basic substances that make up life - fat, protein, carbohydrate and lignin. They are real natural organic matter and the original substance for the generation of oil and gas. These original materials were buried together with the sediments, and after about 5,000 to 10,000 years, they turned into materials that directly generate oil and gas. Petroleum geologists have given the name "kerogen" to these substances that directly and mainly generate oil and gas. The Chinese vividly call kerogen "kerogen". It goes without saying that "kerogen" is the "mother" of petroleum!

Kerogen is in the form of fine flakes or powder, often brown or black, and is dispersed in sediments and sedimentary rocks. Because kerogen is thin, small, and light, it is more abundant in fine-grained sedimentary rocks (such as mudstone, shale, and limestone).

After different organisms die, different types of kerogen are formed: Type I, also called sapropelic type, is mainly produced by the fat of aquatic algae and higher plants, contains more hydrogen, and is the best for producing oil; II Type III, also called humus-sapropel type, is mainly produced by algae and higher plants, and has medium oil-generating ability; Type III, also called humic type, is mainly produced by terrestrial higher plants, and has poor oil-generating ability. The oil-generating kerogen in the Junggar Basin is mainly type II kerogen, that is, humic-sapropel type.