Regarding the theory of the origin of oil, scientists have not come to a consensus. This is a very complex issue, and neither the geology of gas and oil, nor the entire natural science that is currently available to mankind can solve the problem of its solution. Not only theorists, but also practitioners speak about the origin of oil. The famous oil geologist I. M. Gubkin wrote a lot and interestingly about this in the thirties of the last century, discussing various theories of the origin of oil. In general, we can only guess what kind of processes took place over billions of years under the earth's crust, our planet is still a mystery to us in many ways. Man knows little about the true course of the processes of geoevolution, so theories of the origin of oil are very numerous.
Two main theories
When mankind will receive full knowledge about the conditions that contribute to the emergence of oil, when it will study exactly how its deposits are formed in the earth's crust, when it will get acquainted with all structural forms without exceptionlayers, their lithological features that are favorable for the appearance and accumulation of oil - only then will exploration and search for deposits be carried out really expediently. As soon as geological science began to develop, two main theories of the origin of oil emerged. The first relates its formation to living matter. This is an organic theory of the origin of oil. The second says 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 claims that the organic theory appeared later than the inorganic one: until the middle of the nineteenth century, oil was extracted only where it came into contact with the earth's surface - in California, in the Mediterranean, in Venezuela and some other places. The German scientist Humboldt suggested how oil is formed: just like asph alt, 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 С2Н2 with hydrocarbons of the methane series in laboratories. Even later, our Dmitri Ivanovich Mendeleev presented to the world his own "carbide" and not organic theory of the origin of oil. The geologist and scientist Gubkin fiercely criticized her.
Mendeleev and Gubkin
In 1877, the master spoke at the Russian Chemical Society regarding the hypothesis of the origin of oil. It was based on a huge factual material, and therefore immediately became popular. Judging byAccording to the presented evidence, all discovered deposits at that time were concentrated on the edges of mountain-folded formations, they are elongated and located near the zones of large faults. According to Mendeleev, water enters deep into the Earth through faults and reacts with metal carbides, thus contributing to the formation of oil, which then rises and forms deposits. Mendeleev's formula looks like this: 2FeC+3H2O=Fe2O3+C 2H6. Judging by his hypothesis (how oil is formed), this process always occurs, and not only in distant geological periods.
I. M. Gubkin criticized the carbide theory everywhere. This option cannot satisfy a person who knows well geology, who is sure that oil formed quite well even where there are no faults at all that conduct water to liquid carbides. Such cracks simply do not exist in nature - from the Earth's core to the surface. The bas alt belt will not allow either water to penetrate deep into, or finished oil to rise outside. Moreover, all the oil currently produced from great depths speaks against this theory. Another argument for Gubkin was that oil formed inorganically is optically inactive, while natural oil is active, even able to rotate in the plane of polarization of light.
Space is the third theory
The cosmic theory of how oil is formed was also very popular. Today, with the advent of modern technologies in space, it has also suffered a crushing fiasco. Russiangeologist N. A. Sokolov published his theory of the cosmic origin of oil back in 1892, based on the fact that hydrocarbons have always existed on our planet, in its most pristine form, and they were formed at high temperatures when the Earth was just being formed. Cooling, the planet absorbed oil, dissolving it in liquid magma. After the formation of the solid earth's crust, the magma, as it were, gave up hydrocarbons, which, along the cracks, rose to its upper parts, where they thickened from cooling and formed some accumulations. Sokolov's arguments were that hydrocarbons were found in the mass of meteorites.
Gubkin criticized this theory to smithereens, accusing it of being based on purely theoretical calculations that have never been confirmed by geological observations. He was generally sure that there is almost no inorganic oil in nature, and that what is, cannot be of practical importance. The bulk of oil deposits still contains a substance that has gone through all the stages of oil formation, and it is in an organic way. The subsequent discussion of this problem took place for almost a hundred years, with the same disputes and lack of agreement. Soviet oil scientists put forward the most substantiated theory of the inorganic origin of oil.
Scientists of the Soviet Union
Kropotkin, Porfiriev, Kudryavtsev and their other like-minded people tried to prove that from hydrogen and carbon, which are in sufficient quantities in magma, radicals CH, CH2, CH are obtained 3,released from it along with oxygen, which serves as the starting material in cold zones for the formation of oil. Kudryavtsev was sure that the abiogenic origin of oil allows it to pass along with gases into the sedimentary shell of the planet along deep faults from the Earth's mantle. Porfiryev objected that the oil did not come in the form of hydrocarbon radicals from the deep zones, but already fully possessing all the properties of finished natural oil, breaking through porous rocks. He could not answer only the question of how deep the oil was before the migration? Undoubtedly, in the subcortical zones, but this whole theory is just as definitely unprovable as the previous ones.
The inorganic origin of oil was supported by the following arguments:
1. There are also deposits in fundamental crystalline rocks.
2. Gas and oil impurities have been found together with hydrocarbons in volcano emissions, in "explosion pipes", in space.
3. Hydrocarbons can be obtained in the laboratory by creating conditions of high pressures and temperatures.
4. Hydrocarbon gases and liquid hydrocarbon fluids are present in wells that penetrate the crystalline basement (in Sweden, Tatarstan and elsewhere).
5. The organic theory cannot in any way explain the presence of huge concentrations of oil and giant deposits.
6. Gas deposits are of Cenozoic age, and oil deposits are of post-Paleozoic age on ancient mountain platforms.
7. Oil fields are most often associated with deep faults.
Organic theory
In recent years, a lot of publications with new data have appeared. For example, liquid oil is found in the oceans, in their spreading zones. Most of these facts speak of the inorganic origin of oil. However, it is still justified rather sparingly and weakly. That is why she has very few supporters to this day. The vast majority of geologists both abroad and in our country adhere to the organic theory of the origin of oil. Why is this theory so attractive?
The biogenic origin of oil implies its origin from the organic matter of sedimentary subaquatic deposits. The nature of this process is clearly staged. Supporters of the biogenic theory are sure that oil is a product obtained through transformation from organic matter. These are the remains of flora and fauna in sedimentary deposits of marine origin, of which there are literally grams per cubic meter of rock of s alt-bearing deposits, but in oil shale, up to six kilograms can fall on the same cubic meter of sedimentary deposits. In clays - half a kilogram, in siltstones - two hundred grams, in limestones - two hundred and fifty.
Two kinds of organic matter
Sapropel and humus - every person who is fond of plant growing knows what it is. If organic matter accumulates under water, where air access is insufficient, but it is present, it rots, resulting in humus - the main part of the soil that provides fertility. If under water, but without access to oxygen, it accumulatesorganic matter, then "slow distillation" occurs, a reducing chemical process - decay. Shallow pools of stagnant water always have a huge amount of blue-green algae, plankton, including arthropods, which do not live long and die in huge numbers.
A powerful layer of organic silt - sapropel - is formed at the bottom. These are the coastal parts of the seas, lagoons, estuaries. When dry distilled, 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 a person does not have the opportunity to follow all its stages, he finds only the result - huge deposits and deposits of oil. And the processes went on for thousands of years in oil source suites, where a wide variety of sediments formed on the bottom of the oceans and contained diffuse organic matter in quantities not lower than clarke - four hundred grams per cubic meter.
Potential
Source deposits with the highest potential are clay-carbonate, which contain organic matter sapropel. Such deposits are called domanikites. They are found in all Precambrian strata, in Phanerozoic systems, and at the same stratigraphic levels on completely different continents. How did it happen? Three and a half billion years ago, life began on earth. In the Cambrian era, the water shell of the Earth already had the most diverse forms of organic matter. The early Paleozoic was represented by vast seas andoceans, where algae and invertebrates already had a huge number of species.
And far from immediately all this organic world rushed to land. The best conditions for life were created in reservoirs at a depth of sixty to eighty meters - most often these are the shelves of the underwater boundaries of the continents. The closer to land, the more organic matter in the sediments. Inland seas contain up to fifty percent of all deposited organic matter. The best conditions for creating oil are the coastal parts of the seas. Oil comes from the ancient seas, not swamps in freshwater basins.
Stages of oil formation
Academician Gubkin argued that oil formation cannot do without passing through certain stages. The first are sedimentogenesis and diagenesis, when the formation of gas-source and oil-source sediments, that is, the initial organic matter, takes place. The first stage brings with it such biochemical processes that produce kerogen and an abundance of gaseous substances that gradually dissipate.
Some part of them dissolves and concentrates, sometimes even being of interest for industrial production (fifty billion cubic meters of methane in an African lake, for example, or in Japan, gas is also extracted from the sea, in which up to ninety-seven percent of methane). However, at this stage, oil has not yet formed. But further immersion leads the explorer to the oil source rocks of the catagenesis zone, where ammonia, hydrogen sulfide, methane, carbon dioxide, and with them liquid products already arise from the original organic matter.hydrocarbons.
Phases and zones
The main phase is oil formation in the stage of catagenesis at a depth of two to three kilometers of sediments at a temperature of eighty to one hundred and fifty degrees Celsius. The optimal conditions are precisely those under which the decisive factor is high temperature. Oil and gas generation also has specific zones in terms of depth. Up to one hundred and fifty meters is a biochemical zone, which is characterized by the development of biochemical processes in organic matter with the release of gases.
From one to one and a half kilometers down - the transition zone, where all biochemical processes fade. The third zone, from one and a half to six kilometers, is a thermal catalytic zone, it is especially important for the formation of oil. And the fourth - gas, where mainly methane is 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. This zonality is vertical, and the distribution of hydrocarbons in the fields is horizontal.
Production
Earlier, oil was extracted where it comes close to the surface. Now its production has increased many times, and therefore the wells are simply amazing in 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 whichnothing has been mined and is not being mined, although three hundred and thirty-seven million dollars were spent on it. In Austria, a small oil field was found, which unexpectedly turned out to be much larger than the explored one, but oil was discovered at a depth of more than eight kilometers. Upon closer examination, this accumulation turned out to be not oil, but gas, which was impossible to extract - the geological features of this area did not allow. But they still drilled a well, but they didn’t find anything at all, even shale that could be mined.
All countries need oil. Because of her absence, wars constantly start. It is being mined now in previously unseen quantities. The earth is already literally bled dry. Energy experts have calculated how many years the oil available in the bowels of the Earth will last. And it turned out that only fifty-six years of already explored reserves remained. Of course, it will not completely disappear. People already know how to extract oil from shale, oil sand, natural bitumen and much more. Venezuela will have enough oil for a hundred years, Saudi Arabia - almost seventy years, Russia - less than thirty years of being an oil and gas giant.
