The mystery of where the oil came from

How is oil formed?

Oil is the most widely used energy and the most important chemical raw material in the world today. However, regarding the origin of oil, since 200 years ago, two famous Russian scientists respectively proposed the organic and inorganic causes of oil, scholars have been divided into two distinct university groups, each holding one, and it is still debated, difficult to win.

The first person in the world to attempt to explore the origin of oil was Lomonosov of Russia. As early as 1763, he proposed that the fertile substances in the ground, such as oil shale, bitumen, carbon, oil, and amber, were of plant origin. For oil shale is nothing but the ancient black soil of rotten grass and leaves washed down by the rain from the places of fruit-bearing and from the woods, which sinks like silt at the bottom of the lake... Resins and petroleum, by their lightness and the flammability of the resins, are of the same origin.

In 1876, another famous Russian figure, Mendeleev, the founder of the periodic table of elements, put forward a very different idea: the earth is rich in iron and carbon, in the early formation of the Earth may combine to form a large amount of iron carbide, and later interact with overheating groundwater, resulting in hydrocarbons, and hydrocarbons are similar to oil. The hydrocarbons that have been produced rise up along cracks in the earth's crust and are stored and condensed to form petroleum deposits. The "carbonization theory" was popular in the late 19th and early 20th centuries, but soon fell into disrepute because there was no evidence of large quantities of iron carbide deep in the Earth, and there was no possibility of groundwater deep in the Earth.

During this period, astronomers used spectral analysis to find the presence of hydrocarbons in the atmospheres of some planets in the solar system and in the cores of comets. They clearly have nothing to do with biological action (there is a question here). Russia's Sokolov introduced the "universe theory" of petroleum origin in 1889, arguing that when the Earth was born, it was still in a molten fireball state, and absorbed hydrocarbons in the primitive atmosphere. As the Earth cooled, the hydrocarbons that were absorbed condensed and buried in the Earth's crust to form oil. Opponents point out that the Earth formed an atmosphere of much the same composition as the modern one and could not have contained large quantities of hydrocarbons; Even if it did, the hot, molten Earth would have disintegrated long ago.

People call "carbonization theory" and "universe theory" the theory of inorganic origin. There is also an inorganic origin theory, called "volcano theory". There are not many people who hold the "volcanic theory", they believe that oil is the product of volcanic eruption, but the oil deposits located in the world's volcanic belt are very small after all, and this theory cannot explain the formation of a large number of oil deposits that do not exist in the volcanic belt.

In 1888, Jaffe inherited Lomonosov's theory of organic origin and said "challenge" to inorganic origin. He believed that all oil was formed from the fat of Marine animals through a series of changes. Soon, some people put forward the idea that the plant remains in the lake or the seabed under the influence of temperature and pressure to generate organic matter, and then converted into oil, some of which emphasized the importance of Marine plants, and some said that land plants are more favorable to oil generation.

In the 1930s, the former Soviet scientist Gubkin integrated the two opinions and published the "origin of animal and plant mixture", which believed that the mixture of animals and plants was more conducive to the generation of oil after a series of changes. The latest theory of petroleum organic formation holds that the organisms that form petroleum and natural gas include terrestrial and aquatic organisms, and plankton, which is the most prolific organism, is the main one. Together with sediment and other minerals, they are deposited in low-lying shallow seas, bays or lakes, where they first form organic silt, which is covered by new sediment and creates a reducing environment isolated from the air. As the low-lying areas continue to settle, the sediment continues to thicken, the pressure and temperature of the organic sludge continue to increase, and it gradually transforms into oil and natural gas through biochemical, thermal catalytic, thermal cracking, high temperature and other stages.

In the 1940s and 1950s, it was generally believed that petroleum hydrocarbons were formed by the early diagenetic transformation of dispersed organic matter in sedimentary rocks. Some people found hydrocarbon in modern sediments formed almost at the same time, on this basis, put forward the theory of early oil formation of organic origin, also known as "molecular oil generation theory".

In the 1960s, the "molecular oil generation theory" was replaced by the late oil generation theory. Late oil theory believes that when the sediment is buried to a greater depth, to the late diagenesis, the insoluble organic matter in the rock - anhydride tyrogen, to reach mature pyrolysis and generate oil, so it is also called "anhydride tyrogen oil theory".