Oil workers' oil, also known as crude oil, is a brown-black flammable viscous liquid mined from deep underground. Mainly a mixture of alkanes, cycloalkanes and aromatics. It is a mixture formed by long-term evolution of organisms in ancient oceans or lakes, and it belongs to fossil fuels like coal. [Edit this paragraph] The generation and accumulation of oil is 1. The research on oil generation shows that it takes at least 2 million years to generate oil, and the oldest discovered oil reservoir can reach 500 million years. In the long historical process of the earth's continuous evolution, there are some "special" periods, such as Paleozoic and Mesozoic. After the death of a large number of animals and plants, the organic substances that make up their bodies are constantly decomposed and mixed with sediments or carbonate sediments to form sediments. Due to the continuous accumulation and thickening of sediments, the temperature and pressure rise. With the continuous advancement of this process, sediments become sedimentary rocks and then form sedimentary basins, providing a basic geological environment for the generation of oil. With various geological processes, sediments in sedimentary basins are constantly accumulating. When the temperature and pressure reach a certain level, the organic matter of animals and plants in the sediments is transformed into carbon and oxygen compounds, and finally oil and natural gas are generated. 2. Accumulation of oil Oil will not be accumulated in the source rock originally formed in the sedimentary basin like water in the reservoir, but will be squeezed into the rock cracks and pores with low pressure distribution through the pores of the rock until it stays in the completely closed reservoir rock. Reservoir rocks are rocks that accumulate oil. Reservoir rocks form the geological environment of oil storage trap structure, which is a geological structure that prevents oil from moving continuously. This oil accumulates like a sponge absorbs water. It is precisely because of reservoir rocks and trap structures that oil can quietly settle underground, waiting for the arrival of diggers. [Edit this paragraph] On the whole, the distribution of crude oil in the main distribution areas of the world is extremely unbalanced: from the perspective of the eastern and western hemispheres, about 3/4 of the oil resources are concentrated in the eastern hemisphere, and the western hemisphere accounts for1/4; From the perspective of the northern and southern hemispheres, oil resources are mainly concentrated in the northern hemisphere; From the perspective of latitude distribution, it is mainly concentrated in two latitudes: 20-40 and 50-70 north latitude. The two major oil regions, the Persian Gulf and the Gulf of Mexico, and the oil fields in North Africa are all located within 20-40 north latitude, which accounts for 5 1.3% of the world's oil reserves. There are famous Beihai oil fields, Russian Volga and Siberia oil fields and gulf of alaska oil fields in the zone of 50-70 north latitude.