Theories of the origin of oil: organic and inorganic. The stages of oil formation. For how many years will the oil last

Concerning the theory of the origin of oil, scientists have not come to a common opinion. This is a very complex issue, and the problem of its solution is beyond the forces of the geology of gas and oil, nor of all natural science that is currently available to humanity. The origin of oil is spoken not only by theorists, but also by practitioners. The famous oil geologist IM Gubkin in the thirties of the last century wrote about this a lot and interestingly, discussing various theories of the origin of oil. We generally can only guess that the processes have been going on for billions of years under the earth's crust, our planet is in many ways still a mystery to us. A person knows little about the true course of the processes of geoevolution, therefore theories of the origin of oil are very numerous.

Two basic theories

When mankind gets full knowledge of the conditions that contribute to the emergence of oil, when it learns how its deposits are formed in the earth's crust, when it becomes acquainted with all the structural forms of the strata without exception, their lithological features that are favorable for the appearance and accumulation of oil- only then Exploration and prospecting of deposits will be carried out really expediently. As soon as geological science began to develop, two main theories of the origin of oil were outlined. The first relates her education to living matter. This is an organic theory of the origin of oil. The second suggests that both gas and oil arose due to the synthesis of hydrogen and carbon at high pressures and temperatures in the depths of the earth's crust. This is an inorganic theory of the origin of oil.

History argues that organic theory appeared later inorganic: until the mid-nineteenth century, oil was extracted only where it touched the surface of the earth - in California, in the Mediterranean, in Venezuela and elsewhere. German scientist Humboldt assumed how the oil is formed: just like asphalt, as a result of the action of volcanoes. A little later, in the second half of the nineteenth century, chemists already knew how to synthesize acetylene C ₂ H ₂ with methane hydrocarbons in laboratories. Even later our Dmitry Ivanovich Mendeleev was presented to the world with his own "carbide", rather than an organic theory of the origin of oil. The geologist and scholar Gubkin vehemently criticized her.

Mendeleev and Gubkin

In 1877, the master acted in the Russian Chemical Society on the hypothesis of the origin of oil. It was based on a huge factual material, and therefore immediately became popular. Judging from the evidence, all open deposits at that time concentrated on the edges of the mountain-folded formations, they are extended in length and located near the zones of large faults. According to Mendeleyev, through the faults deep into the Earth, water enters and reacts with metal carbides, thus contributing to the emergence of oil, which then rises and forms deposits. Mendeleyev's formula looks like this: 2FeC + 3H ₂ O = Fe ₂ O ₃ + C ₂ H ₆ . Judging by his hypothesis (how oil is formed), this process always happens, and not only in distant geological periods.

IM Gubkin criticized the carbide theory everywhere. This option can not satisfy a person who knows well the geology of a person who is sure that oil has perfectly formed and where there are no faults that conduct water to liquid carbides. Such cracks simply do not exist in nature - from the core of the Earth to the surface. The basalt belt will not allow water to penetrate deep into the ground, nor the finished oil to rise outside. All the more so because against this theory says all the oil, today extracted from huge depths. Argument Gubkin also served as the fact that oil formed inorganic way, optically inactive, but the natural - is active, even able to rotate in the plane of polarization of light.

Cosmos is the third theory

Very popular was the cosmic theory of how oil is formed. Today, with the onset of modern technology, and it has suffered a crushing fiasco. Russian geologist N. A. Sokolov unveiled his theory of the cosmic origin of oil in the distant year of 1892, based on the fact that hydrocarbons existed on our planet always, in its most primordial form, and they were formed at high temperatures when the Earth was only being formed. Cooling, the planet absorbed oil, dissolving it in liquid magma. After the formation of a solid crust, magma seemed to give up hydrocarbons, which along the cracks and rose to its upper parts, where they thickened from cooling and formed some accumulations. Sokolov argued that hydrocarbons were discovered in the mass of meteorites.

Gubkin and this theory criticized to the nines, blamed the fact that its grounds are purely theoretical calculations, which geological observations have never been confirmed. He was generally convinced that there is almost no inorganic oil in nature, and that which is, can not have practical significance. The bulk of oil deposits still contain a substance that has passed through all the stages of oil formation, and it is organic. The subsequent discussion of this problem took almost a hundred years, with the same disputes and lack of agreement. Soviet oil scientists put forward the most valid theory of the inorganic origin of oil.

Scientists of the Soviet Union

Kropotkin, Porfiryev, Kudryavtsev and other like-minded people tried to prove that from hydrogen and carbon, which is sufficient in magma, the radicals CH, CH ₂ , CH ₃ , which are released from it together with oxygen, are obtained, which serves as the starting material in cold zones for Formation of oil. Kudryavtsev was sure that the abiogenic origin of oil allows it to pass along with the gases into the sedimentary shell of the planet through deep faults precisely from the Earth's mantle. Porfiriev objected that oil did not come in the form of hydrocarbon radicals from deep zones, but already fully possessing all the properties of the finished natural oil, breaking through the porous rocks. He could not answer only the question of how deep the oil was before migration. Undoubtedly, in the subcortical zones, but the whole theory is just as unprovable as the previous ones.

The inorganic origin of oil was reinforced by the following arguments:

1. There are also deposits in the fundamental crystalline rocks.

2. Admixtures of gas and oil are found together with hydrocarbons in volcano emissions, in "explosion tubes", in space.

3. Hydrocarbons can be obtained by laboratory means, creating conditions for high pressures and temperatures.

4. Hydrocarbon gases and liquid hydrocarbon fluids are present in the wells that open the crystalline basement (in Sweden, Tatarstan and elsewhere).

5. Organic theory can not explain the presence of huge concentrations of oil and giant deposits.

6. The deposits of gas are of Cenozoic age, and of oil - post-Paleozoic on ancient mountain platforms.

7. Oilfields are most often associated with deep faults.

Organic theory

In recent years, many publications with new data have appeared. For example, liquid oil is found in the oceans, in their spreading zones. Most of these facts indicate the inorganic origin of oil. However, it is still rather sparingly and weakly justified. Therefore, she has very few supporters to this day. The overwhelming majority of geologists, both abroad and in our country, adhere to the organic theory of the origin of oil. What is so attractive about this theory?

The biogenic origin of oil implies its emergence from organic matter of sedimentary subaquatic deposits. The nature of this process is clearly staged. Proponents of the biogenic theory believe that oil is a product obtained through conversion from organic matter. These are the remnants of the animal and plant life in sedimentary deposits of marine origin, of which one gram of salt deposits per liter are literally grams, but in combustible shales the same cubic meter of sediment can account for up to six kilograms. In clay - a half kilogram, in siltstone - two hundred grams, in limestones - two hundred and fifty.

Two kinds of organic matter

Sapropel and humus - every person, keen on plant growing, knows what it is. If the organic matter accumulates under water, where air access is insufficient, but it is, it rotates, humus is obtained - the main part of the soil that provides fertility. If under the water, but without the access of oxygen, organic matter accumulates, then "slow distillation" occurs, the chemical recovery process is rotting. Small pools with stagnant water always have a huge amount of blue-green algae, plankton, including arthropods, which live for a short time and die in huge quantities.

A powerful layer of organic silt - sapropel is formed at the bottom. Such are the coastal parts of the seas, lagoons, estuaries. With dry distillation sapropel produces twenty five percent of the weight of oil-like fatty oils. And the formation of oil is a process so long and complex that it is impossible for a person to follow all its stages, he finds only the result - huge deposits and oil deposits. And the processes took thousands of years in the oil reservoirs, where a variety of deposits formed at the bottom of the oceans and contained a dispersed substance of organic origin in quantities not below the clark - four hundred grams per cubic meter.

Potential

Petroleum deposits with the highest potential - clay-carbonate, which contain organic matter sapropel. Such deposits are called house-builders. They exist in all Precambrian strata, in the Phanerozoic systems, and on the same stratigraphic levels of completely different continents. How did it happen? Three and a half billion years ago, life began on the earth. In the Cambrian era, the water shell of the Earth already had a wide variety of forms of organic matter. Early Paleozoic was represented by immense seas and oceans, where algae and invertebrates already had a huge number of species.

And not all at once all this organic world rushed to the land. The best conditions for life were created in reservoirs at a depth of sixty to eighty meters, most often the shelves of the continental submarine boundaries. The closer to the land, the more organic matter in the sediments. Intracontinental seas contain up to fifty percent of all deposited organic matter. The best conditions for the creation of oil are the coastal parts of the seas. The homeland of oil is the ancient seas, and not the swamps in the freshwater basins.

The stages of oil formation

Academician Gubkin argued that oil formation can not do without passing certain stages. The first - sedimentogenesis and diagenesis, when the formation of gas-mother and oil-mother sediments, that is - the initial organic matter. The first stage carries with it such biochemical processes, under which kerogen is formed and an abundance of gaseous substances, which gradually dissipate.

Some part of them dissolves and concentrates, sometimes even representing the interest of industrial extraction (fifty billion cubic meters of methane in an African lake, for example, or in Japan, too, gas is produced from gas in which up to ninety-seven percent of methane). However, oil has not yet formed at this stage. But a further dive leads the scout to the petroleum rocks of the catagenesis zone, where ammonia, hydrogen sulphide, methane, carbon dioxide, and liquid hydrocarbon products are already emerging from the initial organic matter.

Phases and Zones

The main phase is oil formation in the stage of catagenesis at a depth of two to three kilometers of sediment at a temperature of eighty to one hundred and fifty degrees Celsius. The optimal conditions are those in which the decisive factor is high temperature. Oil and gas generation also has specific zones according to the depth of occurrence. Up to one hundred and fifty meters the zone is biochemical, for which the development of biochemical processes in the organic matter with the release of gases is characteristic.

From one to one and a half kilometers down - the transition zone, where all biochemical processes are damped. The third zone is from one and a half to six kilometers - thermocatalytic, it is especially important for the formation of oil. And the fourth one is gas, where methane is mainly formed. It can be seen that the process begins with the formation of gas, and accompanies oil formation at all stages, and completes this process. Zoning is vertical, and the distribution of hydrocarbons in the fields is horizontal.

Extraction

Previously, oil was extracted where it almost closely approaches the surface. Now its production has increased many times, and therefore the wells are simply amazing by their length. The longest were drilled in the USSR: on Sakhalin - much more than twelve kilometers, and on the Kola Peninsula - 12262 meters. In Qatar, a horizontal well is more than twelve kilometers long, in the United States two nine-kilometer wells. In the Bavarian mountains of Germany there is the same nine-kilometer well, from which nothing was mined or extracted, although they spent three hundred and thirty-seven million dollars on it. In Austria, a small oil field was discovered, which unexpectedly turned out to be much larger than the explored one, but oil was discovered at a depth of more than eight kilometers. On closer examination, this cluster was not oil, but gas, which it was impossible to extract - the geological features of this site were not allowed. And they drilled the well, but they found nothing at all, not even slates, which could be extracted.

All countries need oil. Because of her absence, wars constantly begin. It is now extracted in unprecedented quantities. The earth is already literally exsanguinated. Energy experts have calculated how long the oil available in the bowels of the Earth will last. And it turned out that there were only fifty-six years left for the explored reserves. Of course, it will not disappear completely. People already know how to extract oil from oil shale, oil sand, natural bitumen and much more. Venezuela has enough oil for a hundred years, Saudi Arabia - almost seventy, Russia - less than thirty years of being an oil and gas giant.