China National Offshore Oil Corporation, China Petroleum Development Co., Ltd. China National Petroleum Corporation China National Petroleum Co., Ltd. Daqing oil company ConocoPhillips, Mobil Oil Company 
 Petroleum oil occurs in porous underground rock in the shape of a liquid fuel easily. Also known as crude oil. Generalized oil, usually found naturally in the ground to the main hydrocarbon compounds and mixtures containing a small amount of impurities. This mixture may be gaseous (natural gas), liquid (crude oil) and solid (Pitch and wax). 
 Varying amounts of impurities in liquid and solid non-hydrocarbon compounds, and contain trace elements. The term was first seen in the Northern Song Dynasty China Petroleum Shen Kuo's "Meng Xi Bi Tan." petroleum is the Greek word petra (rock) and the Latin oleum (oil) of the compound word, which means rock oil. The formation of oil and other mineral deposits is different from the accumulation of experience of its generation, primary migration and secondary migration of three stages. 
 Oil is a very complex mixture, its chemical composition with the origin, formation and differentiation, there is no fixed physical constants. Physical properties of oil in the transmitted light from light yellow to dark brown, brown, black (usually dark brown) the proportion of generally 0.75 to 0.98, greater than 1 or less than 0.75 of the oil was also found in nature; viscosity greater close to the water from room temperature to a semi-solid form of heavy oil; oil mainly composed of hydrocarbons, it can be dissolved in neutral organic solvents such as benzene, chloroform, carbon disulfide, ether, etc.; oil, freezing point and the level of liquefied points, depending on the number of alkane polymer content (or the amount of wax resistance is high, typically 10 to 10 ohms; oil most of who have optical activity, that is, when the polarized light through the oil, can rotate polarized light to the right (left Shaoshuo rotation). the physical properties of oil and oil chemical composition. 
 Mainly by the chemical composition of the oil composition of carbon and hydrogen, carbon and hydrogen content of 95% to 99%, followed by sulfur, nitrogen and oxygen and other elements. Oil from the 2000 kinds of compounds. 230 hydrocarbon compounds which, belonging to alkanes, cycloalkanes and aromatic hydrocarbons, are composed of essential oil compounds. Oil in the sulfur, nitrogen, oxygen range of non-hydrocarbon compounds, nitrogen-containing porphyrin compounds, quinoline, pyridine, carbazole and other oxygenates in the organic acids (naphthenic acids, fatty acids, etc.), phenols, ketones. Different compounds have different boiling point, distillation, heating oil, the oil can be separated into different boiling range (ie, distillation range) of the number of parts, the part is a fraction. 
 China's oil and gas industry in China is the first discovery and use of oil country, but almost 100 years, the oil industry is very backward. 1904 to 1949, only 308 tons of oil production. Only the Laojunmiao Yumen Oilfield, Xinjiang Dushanzi oil field, mine fields out of Miaoli County, Taiwan and the northern extension of oil fields. Longchang gas fields and oil groove only two artesian wells and ancient old gas fields have been developed. 50's found the Karamay, cold lakes and ducks and other children Gap oil fields, Daqing Oilfield in 1959 found that large, followed by some major oil fields have been discovered (Table 2). Oil production since 1978 have the 1 million tons. Great potential for oil and gas resources in China, there are more than 300 sedimentary basins in the size of its area of ??450 square kilometers. East 90's stable crude oil production in the annual 64 million tons or so. The formation of "stabilizing the east, the western development" strategy pattern. Xinjiang in 1995, total reserves of 1.94 billion tons of proven natural gas reserves of 110 billion cubic meters, annual output of 12.8 million tons of crude oil. Offshore is developing.