Of the modern theory

In the 50's and 60's. XX century. in the USSR (NA Kudryavtsev, VB porphyry, N. Dolenko etc.) and abroad (the British scientist F. Hoyle and others) revived the various hypotheses of the inorganic (cosmic, volcanic, magmatic) origin of oil . However, in the 6th (1963), 7th (1967) and 8th (1971) International Oil Congress inorganic hypotheses were not supported.

Important for understanding the genesis of oil was to establish in the late XIX - early XX centuries. optical activity of oil, as well as close ties with oil sapropelic organic matter in sedimentary rocks. Sapropelic conjecture first German botanist G. Potonié in 1904-05, further developed by Russian and Soviet scientists - N. Andrusov, Vernadsky, IM Gubkin, ND Zelinsky and others. Sapropelic hypothesis assimilated by the modern theory of the migration of sedimentary origin of oil. Development of ideas about the nature of oil and the conditions of formation of its deposits also contributed works of the German scientist K. Engler, American geologist J. Newberry, E. Orton, D. White, Russian and Soviet scientists - GP Michael, DV Golubyatnikova, MV Abramovich, KI Bogdanovich and others.

This period is characterized by the study of oil have broad geological and geochemical studies aimed at addressing the problem of oil generation and organically related issues oil source sediments. In the USSR, such work performed by AD Archangel in 1925-26. In the U.S., a similar study started in 1926 P. Trask. In 1932 he published a classic work Gubkin "Studies on oil," which played a huge role in the development of ideas about the genesis and formation of its oil deposits. In 1934, in the oil, asphalt and coal deposits were found porphyrins belonging to a molecule of chlorophyll and other natural pigments.

But entirely inorganic theory of the origin of oil is not rejected. There are attempts to combine the organic and non-organic theory of the origin of oil: on the one hand, the radioactive decay in the core hydrogen is formed, which reacts with carbon to form oil-like substance, on the other hand, there are oil biomarkers - compounds definitely organic, with encountered by the "inorganic" oil.

Vitaly Rafailovich Flid, head of the Physical Chemistry of the Moscow Academy of Fine Chemical Technology. Moscow State University, Doctor of Sciences in 2011 [3] stated: "In a few countries - the U.S., Japan, we Troitsk - built systems for simulation of hydrocarbon generation of carbonate and water in the presence of ferrous iron. If you mix calcium carbonate or magnesium salt solution of iron and heated at high pressure, then, as shown in our study, is reliably produced hydrocarbons. At least methane. The gas from the depths of the earth through the channels in the rocks come to the surface facing undergoing different reactions to form heavier hydrocarbons. That is oil. This is the way of formation of mineral oil. Geologists say that there are oil fields, which were completely exhausted, and then the oil they appeared again. Perhaps, this is the oil from the depths of the Earth, which is unlikely to ever end.

Background on the modern theory

Milestones in the long process of scientific solution of the question of the origin of oil identified by Russian scientists. For the first time in 1763 Lomonosov suggested origin of oil from plant residues undergoing carbonization and pressure in the Earth's layers. These ideas are far ahead of University scientific thought of the time, look for the source of oil of inanimate nature.

In 1866, French chemist M. Berthelot suggested that oil is formed in the bowels of the earth under the influence of carbon dioxide on alkali metals. In 1871, French chemist H. Biasson proposed the idea of ​​the origin of oil, by the interaction of water, CO2, H2S with a hot iron.

In 1892, Vladimir Sokolov stated hypothesis of cosmic origin of oil. Under this hypothesis, the raw material for the emergence of petroleum hydrocarbons were contained in the gaseous envelope of the Earth even during her star status. As the cooling of the Earth absorb hydrocarbons molten magma. Then, with the formation of the earth's crust, the hydrocarbons penetrated the sedimentary rocks in the gas phase, condensed and formed oil. [1]

Mendeleev, who shared the first idea of ​​organic origin, was inclined to believe its origins as a result of reactions occurring in deep water at high temperatures and pressures between the metal carbide and water seeping from the ground. [1] The hypothesis of Mendeleev on the origin of oil from inorganic matter is now only of historical interest.

Soviet scientists Vernadsky been proven exceptional ability of organisms that inhabit our planet, to concentrate in the lithosphere huge carbon stores and the enormous role of the latter in the geological processes. Soviet scientist ND Zelinsky showed that some carbon compounds that make up plants and animals at low temperature and under appropriate conditions can form products, it is similar to the oil on the chemical composition and physical properties. A new stage in the development of the origin of oil was discovered by Soviet scientist T. Ginzburg-Karagicheva in waters Bibi Eybat and Surakhani (Baku) at a depth of 2000 m of living bacteria promoting sulfate reduction. This led to the idea of ​​the great role of microorganisms in the fate of the buried organic matter and oil formed from it. Later, these microorganisms were found in the oil fields of the United States.

Laboratory studies have shown that under the action of the organic matter of gamma radiation produced hydrocarbons with the release of free hydrogen. Thus, the presence of radioactive decay in rocks may lead to the formation of free hydrogen for hydrogenation processes in nature. However, the role of ionizing radiation in the origin of oil still not clear. Soviet geologist IM Gubkin, summarizing the results of studies of the nature of oil, came to the conclusion that the process of its formation is continuous and can not be separated from the processes of formation of deposits in the earth of mineral matter on the scale of clusters. Most favorable for the formation of oil are unstable in the last parts of the earth's crust at the boundary of subsidence and uplift. Strong erosion of land in these areas contributed to the rapid accumulation of rainfall, and hence burial of organic material and lowering it into all the deeper zones of the crust. This is accompanied by a lowering of the growth temperature and increasing pressure, facilitate the process of oil and gas formation, aided and activity of anaerobic bacteria buried. In the areas of the Earth's crust dives under certain conditions, could be deposited layers containing large amounts of organic material, which then became part of the oil-producing and oil source rock. In advanced ridges and troughs in geosynclines all geological ages to create favorable conditions for the formation of oil pools where plant and animal remains, mostly plankton, mixed with inorganic substances, marked the beginning of the formation of rocks, then gave oil. High content of organic material characterized by clay and silt sediments that fill the cavities of the seabed, where the water does not mix any waves or ocean currents and where, consequently, the conditions reducing environment favorable to the preservation of organic material and its subsequent changes and the gradual transformation of the oil.

Oil origin

Oil - the result lithogenesis. It is a liquid (basically) a hydrophobic phase products fossilization (disposal) of organic matter (kerogen) in the water-sediment in anoxic conditions.

Oil formation - the step-wise, very long (typically 50-350 Ma) [1], a process that begins as early as living matter. Highlighted a number of stages:
Sedimentation - in which the remains of living organisms fall to the bottom of the basins;
Biochemical - compaction process, dehydration and biochemical processes with limited access to oxygen;
protokatagenez - lower layer of organic residues to a depth of 1.5 - 2 km, the slow rise of temperature and pressure;
mezokatagenez or main phase of oil generation (GFN) - lower layer of organic residues to a depth of 3 - 4 km, when the temperature rises to 150 ° C. In this case, the organic substances undergo catalytic thermal decomposition, resulting in formation of bituminous substances that make up the bulk of mikronefti. Further there is a distillation of the oil due to the pressure difference and stem emigration mikronefti in sand reservoirs, and on them in the trap;
apokatagenez kerogen or main phase of gas generation (GFG) - lower layer of organic residues to a depth of 4.5 km, with the rise in temperature to 180-250 ° C. In this organic matter becomes neftegeneriruyuschy metanogeneriruyuschy potential and realize potential.
IM Gubkin also singled stage destruction of oil mestozarozhdeny.

Strong evidence of the biogenic nature of the parent substance of oil were obtained from a detailed study of the evolution of the molecular composition of hydrocarbons and their biochemical precursors (progenitors) in the source organisms, organic matter and sediments and rocks in various oil from reservoirs. Important was the discovery of oil in the hemofossily - a very unique and often complex molecular designs clearly biogenic nature, that is inherited (in whole or in fragments) of organic matter. Study of the distribution of stable isotopes of carbon (12C, 13C) in the oil, organic matter of rocks and organisms (Vinogradov, EM Galimov) [2] also confirmed ineligibility inorganic hypotheses.


 It is believed that the main source of oil is usually a matter of zooplankton and algae, providing the greatest bio-products in water and the accumulation of organic matter in the sediments of sapropelic type, characterized by a high content of hydrogen (due to the presence of aliphatic and alicyclic kerogen molecular structures).

In ancient times there were warm, nutrient-rich seas, such as the Gulf of Mexico and the ancient Tethys Ocean, where a large amount of organic material falls to the bottom of the ocean, higher than the rate at which it could decompose. As a result of large masses of organic material were buried under subsequent deposits such as shale or salt. This is confirmed by the presence of a thick layer of salt over the oil fields in the Middle East. The formation of salt deposits suggests that these waters for a long time were quite small, poorly communicated to the rest of the ocean and evaporation greatly exceeds that of the sea water from the outside. Subsequently, the band were on the ground as a result of the movement of continents. Conditions are quite unique, so most of the modern organic sediments on the bottom of the ocean waiting for a different fate - the motion of the oceanic crust, they fall into the subduction zone.

Rocks formed from sediments that contain this type of organic matter, potentially oil source. Most often it is clay, at least - carbonate and sandstone-siltstone rocks that during immersion reach the upper half of the zone mezokatageneza which comes into force the main factor of oil generation - long heating of organic matter at temperatures of 50 ° C and above. The upper boundary of the main zone of oil formation located at depths of 1.3-1.7 km (with an average geothermal gradient 4 ° C/100 m) to 2.7-3 km (with a gradient of 2 ° C/100 m) and fixed by changing degree of coalification lignite coal organic matter. Main phase of oil generation confined to the area where coalification of organic matter reaches a degree corresponding coals Mark G. This phase is characterized by a significant increase in thermal and (or) thermal catalytic decomposition polimerlipoidnyh and other components of kerogen. Produced in large quantities petroleum hydrocarbons, including low molecular weight (C5-C15), almost absent in the earlier stages of the transformation of organic matter. These hydrocarbons, giving rise to the gasoline and kerosene fractions of oil, significantly increase the mobility mikronefti. At the same time, due to a decrease of the sorption capacity of source rocks, increasing the internal pressure in them and the allocation of water in the dehydration of clay increases the movement in the coming mikronefti collectors. When migrating to a collector in the trap oil always rises, so its maximum reserves are located at depths of several smaller than the display area of ​​the main phase of oil generation, the lower boundary of which usually corresponds to the zone where the organic matter reaches the degree of coalification rocks, typical coking coals. Depending on the intensity and duration of heating, this boundary is at a depth of (meaning the maximum depth for the entire geological history of this series of sediment) from 3-3.5 to 5-6 km.

Petroleum geology

Enclosing rocks of oil have relatively high porosity and sufficient to eject permeability. Breed, allowing free movement and accumulation in these fluids are called collectors. Porosity depends on all sorted grains, their shape and styling, as well as on the presence of cement. Permeability determined by the size of pores and their communicability. The most important oil reservoirs are sands, sandstones, conglomerates, dolomite, limestone, and other well-permeable rocks, prisoners of impermeable rocks such as clay or plaster. Under favorable conditions, the collectors may be fractured metamorphic and igneous rocks that are in the vicinity of the oil-bearing sedimentary rocks.

Often the oil reservoir is only part of the reservoir and therefore, depending on the nature and degree of cementation porosity rocks (reservoir heterogeneity) found varying degrees of oil saturation in some segments within the reservoir itself. Sometimes this is due to the presence of the cause of non-productive areas of the reservoir. Usually oil deposits accompanied with water, which limits the accumulation downdip layers or along its base. In addition, each oil reserves with it is so-called. film or residual water enveloping the rock particles (sand) and the pore walls. In the case of reservoir rock pinching or cutting his faults, thrusts and t n disjunctive dislocations can deposit either in whole or in part beyond low permeable rocks. In the upper parts of the oil column is sometimes concentrated gas (so-called. "Gas cap"). Well production rate, in addition to the physical properties of the reservoir, its capacity and saturation, determined by the pressure of the dissolved gas in oil and boundary waters. In oil wells can not entirely remove all the oil from the reservoir, a significant amount of it remains in the depths of the earth's crust (see oil recovery and oil production). For a more complete extraction of oil using special techniques, of which the importance is the method of flooding (aquifer, vnutrikonturnogo, focal). Oil in the reservoir is under pressure (elastic expansion and / or the edge of the water and / or gas, as well as dissolved gas cap) so that the opening of the reservoir, especially the first well, accompanied by the risk gazonefteproyavleny (very rare Fountains discharges of oil). Very long time (from the 2nd half of the XIX century.) Geologists believe that the oil fields are timed almost exclusively to the saddle, and only in 1911, IM Gubkin was opened in Maikop's a new type of deposit, marking the alluvial sands and received the name "sleeve-." After more than 10 years, similar deposits have been discovered in the United States. Further development of the exploration in the USSR and the United States completed the discovery of deposits associated with the salt domes, raised, and sometimes poke through the sedimentary strata. The study of oil fields showed that the formation of oil deposits due to different structural forms bends strata stratigraphic relationships and lithological features suites of rocks. Proposed several classifications of fields and oil deposits in Russia and abroad. Oil fields differ from each other by the type of structural forms and conditions of their formation. And oil and gas are different from each other according to the forms of traps, reservoirs and educational conditions in which concentrations of oil.

Oil properties

Physical properties

Oil - the liquid from light brown (almost colorless) to dark brown (almost black) color (even though there are examples of emerald-green oil). The average molecular weight of 220-300 g / mol (rare 450-470). Density 0,65-1,05 (0,82-0,95 usually) g / cm ³; oil whose density is lower than 0.83, is called light, 0,831-0,860 - average above .860 - heavy. The density of oil, as well as other hydrocarbons, is strongly dependent on temperature and pressure [9]. It contains a large number of different organic substances and therefore not characterized by a boiling point, and the initial boiling point of liquid hydrocarbons (typically> 28 ° C, at least ≥ 100 ° C in the case of heavy oils) and fractional composition - Out separate fractions, distilled first at atmospheric pressure and then under vacuum in certain temperature range, usually up to 450-500 ° C (boiling over ~ 80% of the sample), at least 560-580 ° C (90-95%). The crystallization temperature of -60 to + 30 ° C; depends primarily on the content of petroleum wax (what it is, the higher the crystallization temperature) and light fractions (the more, the lower the temperature.) Viscosity varies widely (from 1.98 to 265.90 mm ² / s for various oil produced in Russia), determined the fractional composition of oil and its temperature (the higher and higher the number of light ends, the lower the viscosity), and content of resin-asphaltene substances (the more, the viscosity of the above). Specific heat capacity of 1.7-2.1 kJ / (kg ∙ K), specific heat (low) 43,7-46,2 MJ / kg, the dielectric constant of 2.0-2.5, the electric conductivity of the [specific] from 2 ∙ 10-10 to 0,3 ∙ 10-18 ohm-1 ∙ cm-1.

Oil - a flammable liquid, the flash point of - 35 [10] to +121 ° C (depending on the fractional composition and its content of dissolved gases). Oil soluble in organic solvents, in normal circumstances, is insoluble in water, but it can form stable emulsions. The technology to separate oil from water and dissolved salts conduct dehydration and desalting.
The chemical composition
Main article: List of crude oil products

The overall composition

Petroleum is a mixture of about 1,000 individual substances of which the majority - liquids (> 500 substances or usually 80-90% by weight) and heteroatomic organic compounds (4-5%), mainly sulfur (about 250 agents), nitrogen (> 30 substances) and oxygen (85 substances), and organometallic compounds (mainly vanadium and nickel), and the remaining components - dissolved hydrocarbon gases (C1-C4, from tenths to 4%), water (from trace to 10% ), mineral salts (mainly chlorides, 0,1-4000 mg / l or more), solutions of salts of organic acids, etc., mechanical impurities.

hydrocarbon composition

Basically in paraffin oil are (usually 30-35, sometimes 40-50% by volume) and naphthenic (25-75%). To a lesser extent - aromatic compounds (10-20, at least 35%) and mixed or hybrid, structure (eg, paraffin-naphthenic, naphthene-aromatic).

Oil

Natural oil oily flammable liquid consisting of a complex mixture of hydrocarbons and other organic compounds. In color, the oil is red-brown, sometimes almost black in color, although sometimes there and poorly painted in yellow-green color and even colorless oil, has a peculiar smell, common in sedimentary rocks of the Earth. Today, oil is one of the most important minerals for mankind.

Overview

Oil is found together with gaseous hydrocarbons at depths of tens of meters to 5-6 km. However, at depths greater than 4.5-5 km dominated by gas and gas condensate reservoirs with a minor amount of light fractions. The maximum number of oil deposits located at a depth of 1-3 km. At shallow depths and natural outcrops on surface oil is converted into a thick Malta, semisolid asphalt and other education - such as tar sands and bitumen.

Chemical composition and origin of oil is close to natural gas fuel, ozokerite and asphalt. These resources are collectively called petrolytes. Petrolytes referred to even larger group of so-called caustobioliths - combustible biogenic minerals, which also includes solid fossil fuels.
Origin
Main article: Origin of oil

Oil - the result lithogenesis. It is a liquid (basically) a hydrophobic phase products fossilization (disposal) of organic matter (kerogen) in the water-sediment.

Oil formation - the step-wise, very long (typically 50-350 Ma) [6], a process that begins as early as living matter. Highlighted a number of stages:
Sedimentation - in which the remains of living organisms fall to the bottom of the basins;
Biochemical - compaction process, dehydration and biochemical processes with limited access to oxygen;
protokatagenez - lower layer of organic residues to a depth of 1.5-2 km, with a slow rise in temperature and pressure;
mezokatagenez or main phase of oil generation (GFN) - lower layer of organic residues to a depth of 3-4 km, with the rise in temperature to 150 ° C. In this case, the organic substances undergo catalytic thermal decomposition, resulting in formation of bituminous substances that make up the bulk of mikronefti. Further there is a distillation of the oil due to the pressure difference and stem emigration mikronefti in sand reservoirs, and on them in the trap;
apokatagenez kerogen or main phase of gas generation (GFG) - lower layer of organic residues to a depth of 4.5 km, with the rise in temperature to 180-250 ° C. In this organic matter becomes neftegeneriruyuschy metanogeneriruyuschy potential and realize potential.
IM Gubkin also singled stage destruction of oil mestozarozhdeny.

Strong evidence of the biogenic nature of the parent substance of oil were obtained from a detailed study of the evolution of the molecular composition of hydrocarbons and their biochemical precursors (progenitors) in the source organisms, organic matter and sediments and rocks in various oil from reservoirs. Important was the discovery of oil in the hemofossily - a very unique and often complex molecular designs clearly biogenic nature, that is inherited (in whole or in fragments) of organic matter. Study of the distribution of stable isotopes of carbon (12C, 13C) in the oil, organic matter of rocks and organisms (Vinogradov, EM Galimov) [7] also confirmed ineligibility inorganic hypotheses.

However, in the present, some scientists (mainly in Russia) advocate inorganic hypothesis of the origin of oil. In particular, it is argued that the newly formed in ancient times by organic oil is constantly added oil, which is formed by inorganic. If this is true, it means almost inexhaustible reserves of oil.