Briefly talk about how coal, oil and natural gas are formed.

Coal is formed by long-term geological action after the accumulation layer of ancient plant remains is buried underground. Almost all plant remains can be converted into coal as long as they have the conditions to form coal. However, the coal formed by lower plant remains is small in distribution and thin in thickness, and is rarely used. Those coals with wide distribution, large scale and wide utilization, They are all formed by the remains of higher plants (mainly the remains of ancient ferns, conifers and some angiosperms).

When tall trees fall down, they will be submerged by water, which will cause the situation that fallen trees are isolated from oxygen. In an anoxic environment, plants will not decompose and rot quickly. With the increasing number of fallen trees, the accumulation layer of plant remains will eventually be formed. Under the action of microorganisms, the accumulation layer of these ancient plant remains. Constantly decomposed and combined, the peat layer is gradually formed, which is the first step in the formation of coal.

Due to the movement of the earth's crust, the peat layer sinks and is covered by sediments such as sediment and rocks. At this time, on the one hand, the peat layer is under heavy pressure from the sediment and rocks above, on the other hand, and more importantly, it is also under the action of geothermal energy. Under such conditions, the peat layer is subjected to geothermal energy. Compacted, the specific gravity increases, and the content of carboniferous gradually increases, the content of oxygen gradually decreases, and the content of humic acid gradually decreases. After these processes are completed, peat becomes lignite.

If lignite continues to be subjected to increasing temperature and pressure, it will cause further changes in its internal molecular structure, physical properties and chemical properties, and lignite will gradually become bituminous coal or anthracite.

Oil is the remains of ancient organisms. Accumulated in lakes, seas, or land, it is transformed by complex biological and chemical actions under the action of high temperature and high pressure.

Oil is generated bit by bit in the stratum and floats in the stratum. Due to buoyancy, oil points slowly move upward along the stratum or fault every year until they are stopped by an oil-tight closed stratum. When more and more oil points gather in this closed stratum, The oil field is formed.

Natural gas is a multi-component mixed gas, the main component is alkanes, in which methane accounts for the vast majority, and a small amount of ethane, propane and butane. In addition, it generally contains hydrogen sulfide, carbon dioxide, nitrogen and water vapor, and a small amount of inert gases, such as helium and argon. Under standard conditions, methane to butane exist in gas state, and pentane is above liquid.

Natural gas system paleontological remains are deposited underground for a long time.