The composition and nature of oil

Oil, also known as crude oil, is a brown-black combustible viscous liquid that is mined deep underground. Petroleum is a mixture of creatures in the ancient oceans or lakes that have evolved over a long period of time, and belongs to the same fossil fuel as coal. The nature of petroleum varies from place of origin, with a density of 0.8 to 1.0 g/cm3, a wide range of viscosity, a large difference in freezing point (30 to -60°C), and a boiling point range of room temperature to above 500°C. Organic solvents, insoluble in water, but can form emulsions with water. The chemical elements that make up the oil are mainly carbon (83% to 87%), hydrogen (11% to 14%), and the rest are sulfur (0.06% to 0.8%), nitrogen (0.02% to 1.7%), and oxygen (0.08%~ 1.82%) and trace metal elements (nickel, vanadium, iron, etc.). Hydrocarbons formed by carbon and hydrogenation constitute the major components of petroleum, accounting for approximately 95% to 99%. Compounds containing sulfur, oxygen, and nitrogen are harmful to petroleum products and should be removed as much as possible during petroleum processing.

The hydrocarbons in different origins have different structures and proportions of hydrocarbons, but they mainly belong to three categories: alkane, cycloalkane, and aromatic hydrocarbons. The petroleum, which is usually dominated by alkanes, is called paraffin-based petroleum; the naphthenic, aromatic hydrocarbon-based ones are called cyclic hydrocarbon-based petroleum; intermediate oil between them is called. The main crude oil in China is characterized by high wax content, high freezing point, low sulfur content, moderate nickel and nitrogen content, and very low vanadium content. Except for a few oil fields, crude oil has less gasoline distillate and residual oil accounts for 1/3. The oils that make up different types have different processing methods and the performance of the products is different. They should be used to their best use. Daqing crude oil is characterized by high wax content, high condensation point, low sulfur content, and belongs to low-sulfur paraffin base crude oil.