Oil is undoubtedly one of the most important energy sources in the world today, and its role is not limited to acting as a fuel, the production of rubber, paint, and even leather requires oil as a solvent.
Interestingly, although oil is an indispensable and important energy source for modern civilization, we are still not very clear about the source of oil. Isn't oil extracted from oil fields? Of course, oil is extracted from the ground, but the question is where does the oil underground come from? In addition to oil, there is a very important energy source is also extracted from the ground, it is coal, and the cause of coal has been basically figured out, the relevant evidence is relatively sufficient, basically we can determine that the formation of coal is derived from ancient plants. Unlike coal, there is relatively little theoretical basis and factual evidence for the formation of oil, so there are still many opinions.
Some people say that oil is an innate substance on the earth, which originated from the beginning of the formation of the earth, and then deposited into the ground as the molten earth gradually cooled.
This claim is not entirely impossible, after all, there is no conclusive conclusion on the cause of oil, but this statement is not accepted by the vast majority of scientists, because there is no evidence to support this claim for the time being. So far, the most accepted cause of oil is the "bio-oil hypothesis", which holds that the formation of oil is derived from ancient microorganisms, including algae, plankton and benthic plants in the ocean. If it is true that bio-oil is said, then how did paleontology become oil?
In nature, there are producers, consumers, and decomposers, and the decomposers refer to all kinds of bacteria.
Usually, after the death of the organism, it will be decomposed by the decomposer, and then decay and disappear into energy, so how can it be preserved and turned into oil? Although the decomposer is powerful, but not all can be decomposed, in the cell membrane of microorganisms there is a lipid molecule, this lipid molecule is very similar in nature to fat, they have a tough texture, it is difficult to be recycled by the decomposer, so after the death of the organism, these lipid molecules will remain and accumulate on the seabed. Later, with the change of geology, these accumulated lipid molecules are deposited downwards and become deposited organic matter. At first, they did not change much, but as the depth increased, the pressure and temperature gradually increased, and when they reached a position below 2000 meters, the change quietly occurred.
Under the action of high temperature and pressure, these organic matter are converted into a complex compound, which we call "kerogen".
Kerogen can produce hydrocarbons, after which smaller hydrocarbon molecules become natural gas, while larger hydrocarbon molecules form oil. The oil that was initially formed was relatively dispersed, and then they converged into the reservoir under the action of transport, and slowly formed an oil field, so the oil reserves we found were usually calculated as "100 million tons". Some people say that there is so much oil in one oil field, where do so many ancient organisms come from? In fact, the oil in the oil field is not formed at one time, but is formed by transportation and convergence.
Why does bio-oil theory have the broadest support?
Although the bio-oil hypothesis is still a hypothesis in nature, it is one of the most evidence-based of many hypotheses about oil formation. In the bio-oil hypothesis, oil is initially formed by lipid molecules that are not easy to decompose, and the oil molecule itself is very similar to the lipid molecular structure in the bacterial cell membrane, and then some petroleum molecules are very similar to the structure of chlorophyll. Of course, this evidence alone is not enough to draw definitive conclusions, but they do increase the credibility of the bio-oil theory. So why is there so much evidence to support it, and the bio-oil theory is still not completely convincing? Because we haven't fully understood the chemical processes of petroleum formation.
The bio-oil hypothesis only gives the basic transition process from biology to oil, but does not specify its chemical transformation process.
For example, how does deposited organic matter react to become kerogen? How does Kerogen produce hydrocarbons and eventually oil and gas? All of this is still a mystery. According to the bio-oil hypothesis, oil is formed by paleontology, and the formation time has a history of hundreds of millions of years, if the formation process of oil is so long, will it be exhausted one day? This is not easy to answer, because the current amount of oil reserves underground can not be fully determined, and with the progress of science and technology, human ability to extract oil will also improve, many previously can not be explored, or explored but not the ability to extract oil is constantly becoming a new recoverable oil field, so no one can say how long the oil on the earth can be used.