It is customary to refer to unprocessed oil as crude oil. A dark brown, green fluorescence, viscous oily liquid with a special odor, it is a mixture of various liquid hydrocarbons such as alkanes, naphthenes, aromatic hydrocarbons and alkenes.

The main components are carbon and hydrogen, accounting for 83-87% and 11-14% respectively; there are also a small amount of sulfur, oxygen, nitrogen and trace amounts of phosphorus, arsenic, potassium, sodium, calcium, magnesium, nickel, iron, elements such as vanadium. The specific gravity is 0.78~0.97, the molecular weight is 280~300, and the freezing point is -50~24℃. Crude oil can be refined and processed to obtain various fuel oil, solvent oil, lubricating oil, lubricating grease, paraffin, asphalt, liquefied gas, aromatic hydrocarbon and other products, providing fuel, raw materials and chemical products for various sectors of the national economy.