One of the pressing problems in the oil and gas sector today is the problem of flaring associated petroleum gas (APG). It entails economic, environmental, social losses and risks for the state, and becomes even more relevant with the growing global trend towards transitioning the economy to a low-carbon and energy-efficient mode of development.
APG is a mixture of hydrocarbons that are dissolved in oil. It is found in oil reservoirs and is released to the surface during the extraction of “black gold”. APG differs from natural gas in that, in addition to methane, it consists of butane, propane, ethane and other heavier hydrocarbons. In addition, non-hydrocarbon components can be found in it, such as helium, argon, hydrogen sulfide, nitrogen, and carbon dioxide.
Issues of APG use and disposal are common to all oil-producing countries. And for Russia they are more relevant, due to the fact that our state, according to the World Bank, is at the top of the list of countries with the highest rates of APG flaring. According to expert research, Nigeria took first place in this area, followed by Russia, and then Iran, Iraq and Angola. Official data says that annually in our country 55 billion m3 of APG is extracted, of which 20-25 billion m3 is burned, and only 15-20 billion m3 ends up in the chemical industry. Most gas is burned in hard to reach places oil production in Eastern and Western Siberia. Due to the high illumination at night, the largest metropolises of Europe, America and Asia, as well as sparsely populated areas of Siberia, are visible from space due to the huge number of oil flares burning APG.
One aspect of this problem is environmental. When this gas is burned, a large amount of harmful emissions are released into the atmosphere, which leads to deterioration of the environment s, destruction of non-renewable natural resources, develops negative planetary processes that have an extremely negative impact on the climate. According to recent annual statistics, the combustion of APG in Russia and Kazakhstan alone releases more than a million tons of pollutants into the atmosphere, which include carbon dioxide, sulfur dioxide, and soot particles. These and many other substances naturally enter the human body. Thus, studies in the Tyumen region have shown that the incidence rate of many classes of diseases here is much higher than in other regions of Russia. This list includes diseases reproductive system, hereditary pathologies, weakened immunity, cancer.
But the problems of APG utilization pose not only environmental issues. They are also related to the issues of large losses in the state’s economy. Associated petroleum gas is an important raw material for the energy and chemical industries. It has a high calorific value, and the methane and ethane contained in APG are used in the production of plastics and rubber; its other elements are valuable raw materials for high-octane fuel additives and liquefied hydrocarbon gases. The scale of economic losses in this area is enormous. For example, in 2008, oil and gas production enterprises in Russia burned more than 17 billion m3 of associated gas and 4.9 billion m3 of natural gas, extracting gas condensate. These indicators are similar to the annual need of all Russians for domestic gas. As a consequence of this problem, economic losses for our country amount to 2.3 billion dollars a year.
The problem of APG utilization in Russia depends on many historical reasons that still do not allow it to be solved in a simple and quick ways. It originates in oil industry THE USSR. At that time, the focus was only on giant fields, and the main goal was to produce huge volumes of oil at minimal costs. In view of this, processing of associated gas was considered a secondary issue and less profitable project. A certain recycling scheme, of course, was adopted. To do this, in the most large places During the period of oil production, no less large gas processing plants with an extensive gas collection system were built, which were focused on processing raw materials from nearby fields. It is quite obvious that this technology can only work effectively on large production, and is untenable in medium and small fields, which have been most actively developed recently. Another problem with the Soviet scheme is that its technical and transport characteristics do not allow the transportation and processing of gas enriched with heavy hydrocarbons due to the impossibility of pumping it through pipelines. Therefore, it still has to be burned in torches. In the USSR, gas collection and supply to factories were financed from a single system. After the union collapsed, independent oil companies were formed, in whose hands the sources of APG were concentrated, while gas delivery and collection remained with cargo processors. The latter became monopolists in this area. Thus, oil producers simply had no incentive to invest in the construction of gas gathering facilities at new fields. Moreover, the use of APG requires huge investments. It is cheaper for companies to flare this gas than to build a collection and processing system.
The main reasons for APG flaring can be outlined as follows. There are no cheap technologies that will allow the utilization of gas enriched in heavy hydrocarbons. There is not enough processing capacity. Different compositions of APG and natural gas limit oil workers' access to the Unified Gas Supply System, which is filled with natural gas. The construction of the necessary gas pipelines greatly increases the price of produced gas compared to natural gas. The existing control system in Russia for the implementation of license agreements is also imperfect. Fines for emissions of harmful substances into the atmosphere are much higher less costs for APG utilization. On Russian market There are practically no technologies that would collect and process this gas. Similar solutions exist abroad, but their use is very slow at a high price, as well as the necessary adaptation to Russian conditions, both climate and legislative. For example, our industrial safety requirements are more stringent. There are already cases where customers invested huge sums and ended up with equipment that was impossible to operate. Therefore, our own production of gas pumping compressor stations and APG compression plants is an important issue for the Russian oil and gas industry. Kazan PNG-Energy and Tomsk BPC Engineering are already working on its solution. Several projects on the problem of APG utilization are at different stages of development in Skolkovo.
The Government of the Russian Federation wishes to bring the situation with APG to world standards. Questions about the necessary liberalization of prices for this product were raised already in 2003. In 2007, the latest data on the volume of APG burned in flares was published - this is a third of the total product. In the annual Address of the President of the Russian Federation to the Federal Assembly of the Russian Federation dated April 26, 2007, Vladimir Putin drew attention to the problem and instructed the government to prepare a set of measures to resolve this issue. He proposed increasing fines, creating an accounting system, tightening licensing requirements for subsoil users, and bringing the level of APG utilization to the world average - 95% by 2011. But the Ministry of Energy has calculated that such a target can be achieved, according to the most optimistic forecasts, only by 2015. Khanty-Mansi Autonomous Okrug, for example, currently processes 90%, with eight gas processing plants in operation. The Yamal-Nenets Autonomous Okrug is characterized by gigantic uninhabited territories, which complicates the issue of APG utilization, so about 80% is used here, and the district will reach 95% only in 2015-2016.
The basis of associated petroleum gas is a mixture of light hydrocarbons, including methane, ethane, propane, butane, isobutane and other hydrocarbons that are dissolved in oil under pressure (Figure 1). APG is released when pressure decreases during oil recovery or during the separation process, similar to the process of carbon dioxide released when opening a bottle of champagne. As the name suggests, associated petroleum gas is produced simultaneously with oil and, in fact, is a by-product of oil production. The volume and composition of APG depends on the production area and the specific properties of the deposit. In the process of production and separation of one ton of oil, you can obtain from 25 to 800 m3 of associated gas.
Burning associated petroleum gas in field flares is the least rational way to use it. With this approach, APG essentially becomes a waste product from the oil production process. Incineration may be justified when certain conditions, however, as world experience shows, effective public policy makes it possible to achieve a level of APG combustion of several percent of the total volume of its production in the country.
Currently, there are two most common ways to use associated petroleum gas, alternative to flaring. Firstly, this is the injection of APG into oil-bearing formations to enhance oil recovery or to possibly preserve it as a resource for the future. The second option is to use associated gas as fuel for power generation (Scheme 1) and the needs of the enterprise at oil production sites, as well as for generating electricity and transmitting it to the general power grid.
At the same time, the option of using APG for power generation is also a method of burning it, but it is somewhat more rational, since it is possible to obtain a beneficial effect and somewhat reduce the impact on the environment. Unlike natural gas, the methane content of which is in the range of 92-98%, associated petroleum gas contains less methane, but often has a significant proportion of other hydrocarbon components, which can reach more than half of the total volume. APG may also contain non-hydrocarbon components - carbon dioxide, nitrogen, hydrogen sulfide and others. As a result, associated petroleum gas by itself is not a sufficiently effective fuel.
The most rational option is the processing of APG - its use as a raw material for gas and petrochemicals - which makes it possible to obtain valuable products. As a result of several stages of processing of associated petroleum gas, it is possible to obtain materials such as polyethylene, polypropylene, synthetic rubbers, polystyrene, polyvinyl chloride and others. These materials, in turn, serve as the basis for a wide range of products, without which it is unthinkable modern life people and the economy, including: shoes, clothing, containers and packaging, dishes, equipment, windows, all kinds of rubber products, cultural and household goods, pipes and pipeline parts, materials for medicine and science, etc. It should be noted that APG processing also makes it possible to isolate dry stripped gas, which is an analogue of natural gas, which can be used as a more efficient fuel than APG.
The level of extracted associated gas used for gas and petrochemicals is a characteristic innovative development oil and gas and petrochemical industries, how effectively hydrocarbon resources are used in the country's economy. Rational use of APG requires the availability of appropriate infrastructure, effective government regulation, systems of assessment, sanctions and incentives for market participants. Therefore, the share of APG used for gas and petrochemicals can also characterize the level economic development countries.
Achieving a 95-98% level of utilization of associated petroleum gas extracted throughout the country and a high degree of its processing to produce valuable products, including gas and petrochemicals, are among the important directions for the development of the oil and gas and petrochemical industry in the world. This trend is typical for developed countries rich in hydrocarbons, such as Norway, the USA and Canada. It is also typical for a number of countries with economies in transition, for example Kazakhstan, as well as developing countries, for example Nigeria. It should be noted that Saudi Arabia- the leader of world oil production - becomes one of the leaders of the world gas and petrochemical industry.
Currently, Russia occupies an “honorable” first place in the world in terms of APG combustion volumes. In 2013, this level, according to official data, was about 15.7 billion m3. At the same time, according to unofficial data, the volume of associated petroleum gas flaring in our country may be significantly higher - at least 35 billion m3. At the same time, even based on official statistics, Russia is significantly ahead of other countries in terms of APG flaring volumes. According to official data, the level of APG use by methods other than flaring in our country in 2013 averaged 76.2%. Of this, 44.5% was processed at gas processing plants.
Demands to reduce the level of APG combustion and increase the share of its processing as a valuable hydrocarbon raw material have been put forward by the leadership of our country over the past few years. Currently, Russian Government Decree No. 1148 of November 8, 2012 is in force, according to which oil producing companies are required to pay high fines for excess combustion - above the 5% level.
It is important to note that the accuracy of official statistics regarding recycling rates is seriously questionable. According to experts, a significantly smaller share of extracted APG is processed - about 30%. And not all of it is used to produce gas and petrochemical products; a significant part is processed to produce electricity. Thus, the real share effective use APG - as a raw material for gas and petrochemicals - can account for no more than 20% of the total volume of produced APG.
Thus, even based on official data, considering only the volumes of APG flaring, we can conclude that more than 12 million tons of valuable petrochemical raw materials are lost annually, which could be obtained by processing associated petroleum gas. Important products and goods for the domestic economy could be produced from these raw materials; it could become the basis for the development of new industries, the creation of new jobs, including for the purpose of replacing imported products. According to the World Bank, additional income The Russian economy from qualified processing of APG could amount to more than $7 billion annually, and according to the Ministry of Natural Resources and Environment, our economy loses $13 billion every year.
At the same time, if we take into account the volumes of associated gas flaring at oil fields for our own needs and power generation, the possibility of obtaining raw materials and, accordingly, additional benefits for the economy of our country can be twice as high.
The reasons for the irrational use of associated gas in our country are associated with a number of factors. Often, oil production sites are located far from the infrastructure for collecting, transporting and processing oil gas. Limited access to the main gas pipeline system. The lack of local consumers of APG processing products, the lack of cost-effective solutions for rational use - all this leads to the fact that the simplest solution for oil producing companies is often the flaring of associated gas in the fields: in flares or to generate electricity and domestic needs. It should be noted that the prerequisites for the irrational use of associated petroleum gas were formed back in the initial stages development of the oil industry, back in the Soviet period.
Currently, insufficient attention is paid to assessing the economic losses of the state from irrational use - flaring of associated petroleum gas in the fields. However, APG flaring causes significant damage not only to the economies of oil-producing countries, but also to the environment. Environmental damage most often has an accumulative nature and leads to long-term and often irreversible consequences. In order for assessments of environmental damage and economic losses not to be averaged and one-sided, and for the motivation to solve the problem to be meaningful, it is necessary to take into account the scale of our country and the interests of all parties.
Before the Great Patriotic War industrial reserves natural gas were known in the Carpathian region, the Caucasus, the Volga region and the North (Komi ASSR). The study of natural gas reserves was associated only with oil exploration. Industrial reserves of natural gas in 1940 amounted to 15 billion m3. Then gas deposits were discovered in the North Caucasus, Transcaucasia, Ukraine, the Volga region, Central Asia, Western Siberia and Far East. As of January 1, 1976, proven natural gas reserves amounted to 25.8 trillion m3, of which in the European part of the USSR - 4.2 trillion m3 (16.3%), in the East - 21.6 trillion m3 (83. 7%), including 18.2 trillion m3 (70.5%) in Siberia and the Far East, 3.4 trillion m3 (13.2%) in Central Asia and Kazakhstan. As of January 1, 1980, potential natural gas reserves amounted to 80–85 trillion m3, explored reserves amounted to 34.3 trillion m3. Moreover, reserves increased mainly due to the discovery of deposits in the eastern part of the country - proven reserves there were at a level of about
30.1 trillion m 3, which amounted to 87.8% of the all-Union total.
Today, Russia has 35% of the world's natural gas reserves, which amounts to more than 48 trillion m3. The main areas of natural gas occurrence in Russia and the CIS countries (fields):
West Siberian oil and gas province:
Urengoyskoye, Yamburgskoye, Zapolyarnoye, Medvezhye, Nadymskoye, Tazovskoye – Yamalo-Nenets Autonomous Okrug;
Pokhromskoye, Igrimskoye – Berezovsky gas-bearing region;
Meldzhinskoe, Luginetskoe, Ust-Silginskoe - Vasyugan gas-bearing region.
Volga-Ural oil and gas province:
the most significant is Vuktylskoye, in the Timan-Pechora oil and gas region.
Central Asia and Kazakhstan:
the most significant in Central Asia is Gazlinskoye, in the Fergana Valley;
Kyzylkum, Bayram-Ali, Darvazin, Achak, Shatlyk.
North Caucasus and Transcaucasia:
Karadag, Duvanny – Azerbaijan;
Dagestan Lights – Dagestan;
Severo-Stavropolskoye, Pelachiadinskoye - Stavropol Territory;
Leningradskoye, Maikopskoye, Staro-Minskoye, Berezanskoye - Krasnodar region.
Natural gas deposits are also known in Ukraine, Sakhalin and the Far East. Western Siberia stands out in terms of natural gas reserves (Urengoyskoye, Yamburgskoye, Zapolyarnoye, Medvezhye). Industrial reserves here reach 14 trillion m3. Especially important Yamal gas condensate fields (Bovanenkovskoye, Kruzenshternskoye, Kharasaveyskoye, etc.) are now being acquired. On their basis, the Yamal - Europe project is being implemented. Natural gas production is highly concentrated and is focused on areas with the largest and most profitable fields. Only five fields - Urengoyskoye, Yamburgskoye, Zapolyarnoye, Medvezhye and Orenburgskoye - contain 1/2 of all industrial reserves in Russia. Reserves of Medvezhye are estimated at 1.5 trillion m3, and Urengoyskoe - at 5 trillion m3. The next feature is the dynamic location of natural gas production sites, which is explained by the rapid expansion of the boundaries of identified resources, as well as the comparative ease and low cost of involving them in development. In a short period of time, the main centers for natural gas production moved from the Volga region to Ukraine and the North Caucasus. Further territorial shifts are caused by the development of deposits in Western Siberia, Central Asia, the Urals and the North.
After the collapse of the USSR, Russia experienced a decline in natural gas production. The decline was observed mainly in the Northern economic region (8 billion m 3 in 1990 and 4 billion m 3 in 1994), in the Urals (43 billion m 3 and 35 billion m 3), in the West Siberian economic region (576 And
555 billion m3) and in the North Caucasus (6 and 4 billion m3). Natural gas production remained at the same level in the Volga (6 billion m3) and Far Eastern economic regions. At the end of 1994, there was an upward trend in production levels. From the republics of the former USSR Russian Federation produces the most gas, in second place is Turkmenistan (more than 1/10), followed by Uzbekistan and Ukraine. Special meaning acquires natural gas production on the shelf of the World Ocean. In 1987, 12.2 billion m 3 was produced from offshore fields, or about 2% of the gas produced in the country. Associated gas production in the same year amounted to 41.9 billion m3. For many areas, one of the gaseous fuel reserves is the gasification of coal and shale. Underground gasification of coal is carried out in the Donbass (Lisichansk), Kuzbass (Kiselevsk) and the Moscow region (Tula).
Natural gas was and remains an important export product in Russian foreign trade. The main natural gas processing centers are located in the Urals (Orenburg, Shkapovo, Almetyevsk), in Western Siberia (Nizhnevartovsk, Surgut), in the Volga region (Saratov), in the North Caucasus (Grozny) and in other gas-bearing provinces.
It can be noted that gas processing plants gravitate towards sources of raw materials - fields and large gas pipelines. The most important use of natural gas is as a fuel. Last thing time is running trend towards an increase in the share of natural gas in the country's fuel balance. As a gaseous fuel, natural gas has great advantages not only over solid and liquid fuels, but also over other types of gaseous fuels (blast furnace, coke oven gas), since its calorific value is much higher. Methane is the main one component this gas. In addition to methane, natural gas contains its closest homologues - ethane, propane, butane. The higher molecular mass hydrocarbon, the less it is usually contained in natural gas.
Compound natural gas varies from field to field.
Average composition of natural gas:
|
CH 4 |
C2H6 |
C 3 H 8 |
C4H10 |
C5H12 |
N 2 and other gases |
|
|
Natural gas (% by volume) |
80-98 |
0,5-4,0 |
0,2-1,5 |
0,1-1,0 |
0-1,0 |
2-13 |
The most valuable natural gas with a high methane content is Stavropol (97.8% CH 4), Saratov (93.4%), Urengoy (95.16%).
Natural gas reserves on our planet are very large (approximately 1015 m3). We know more than 200 deposits in Russia; they are located in Western Siberia, the Volga-Ural basin, and the North Caucasus. Russia holds the first place in the world in terms of natural gas reserves.
Natural gas is the most valuable type of fuel. When gas is burned, a lot of heat is released, so it serves as an energy-efficient and cheap fuel in boiler plants, blast furnaces, open-hearth furnaces and glass melting furnaces. The use of natural gas in production makes it possible to significantly increase labor productivity.
Natural gas is a source of raw materials for the chemical industry: the production of acetylene, ethylene, hydrogen, soot, various plastics, acetic acid, dyes, medicines and other products.
Associated petroleum gas is a gas that exists together with oil, it is dissolved in oil and is located above it, forming a “gas cap”, under pressure. At the exit from the well, the pressure drops and associated gas is separated from the oil.
Compound associated petroleum gas varies from field to field.
Average gas composition:
|
CH 4 |
C2H6 |
C 3 H 8 |
C4H10 |
C5H12 |
N 2 and other gases |
|
|
Passing petroleum gas (% by volume) |
Associated petroleum gas is also natural in origin. It received a special name because it is located in deposits along with oil:
Or dissolved in it,
Or is in a free state
Associated petroleum gas also mainly consists of methane, but it contains significant amount and other hydrocarbons.
This gas was not used in past times, but was simply burned. Currently, it is captured and used as fuel and valuable chemical raw materials. The possibilities for using associated gases are even wider than natural gas, because... their composition is richer. Associated gases contain less methane than natural gas, but they contain significantly more methane homologues. To use associated gas more rationally, it is divided into mixtures of a narrower composition. After separation, gas gasoline, propane and butane, and dry gas are obtained.
|
III |
|||
|
Hydrocarbons |
CH4, C2H6 |
C3H8, C4H10 |
C5H12, C6H14, etc. |
|
Released mixtures |
Dry gas |
Propane-butane mixture |
Gas gasoline |
|
Application |
Dry gas, similar in composition to natural gas, is used to produce acetylene, hydrogen and other substances, and also as fuel. |
Propane and butane in a liquefied state are widely used as fuel in everyday life and in automobile transport. |
Gasoline containing volatile liquid hydrocarbons is used as an additive to gasoline for better ignition when starting the engine. |
Individual hydrocarbons are also extracted - ethane, propane, butane and others. By dehydrogenating them, unsaturated hydrocarbons are obtained - ethylene, propylene, butylene, etc.
Associated petroleum gas.
Associated petroleum gas is also natural gas in origin. It received a special name because it is located in deposits together with oil - it is dissolved in it and is located above the oil, forming a gas “cap”. Associated gas dissolves in oil because it is under pressure at great depths. When extracted to the surface, the pressure in the liquid-gas system drops, as a result of which the solubility of the gas decreases and gas is released from the oil. This phenomenon makes oil production a fire and explosion hazard. The composition of natural and associated gases from different fields is different. Associated gases are more diverse in hydrocarbon components than natural ones, therefore it is more profitable to use them as chemical raw materials.
Associated gas, unlike natural gas, contains mainly propane and butane isomers.
Characteristics of associated petroleum gases
Associated petroleum gas is also formed as a result of natural cracking of oil, therefore it includes saturated (methane and homologues) and unsaturated (ethylene and homologues) hydrocarbons, as well as non-flammable gases - nitrogen, argon and carbon dioxide CO 2. Previously, associated gas was not used and was immediately flared at the field. It is now increasingly being captured because, like natural gas, it is a good fuel and valuable chemical raw materials.
Associated gases are processed at gas processing plants. From them they produce methane, ethane, propane, butane and “light” gas gasoline containing hydrocarbons with the number of carbon atoms 5 or more. Ethane and propane are dehydrogenated to produce unsaturated hydrocarbons - ethylene and propylene. A mixture of propane and butane (liquefied gas) is used as household fuel. Gasoline is added to regular gasoline to speed up its ignition when starting internal combustion engines.
Oil
Oil is a liquid combustible fossil of an oily appearance from yellow or light brown to black with a characteristic odor, with a density of 0.70 - 1.04 g/cm³, lighter than water, insoluble in water, it is a natural complex mixture of predominantly liquid hydrocarbons, in mainly alkanes of linear and branched structure, containing from 5 to 50 carbon atoms in molecules, with other organic substances. Since oil is a mixture of various hydrocarbons, it does not have a specific boiling point. Gaseous and solid components of oil are dissolved in its liquid components, which determines its state of aggregation.
Its composition significantly depends on the place of its extraction. The composition of oils is paraffinic, naphthenic and aromatic. For example, Baku oil is rich in cyclic hydrocarbons (up to 90%), saturated hydrocarbons predominate in Grozny oil, and aromatic hydrocarbons predominate in Ural oil. The most common oils are of mixed composition. Based on density, light and heavy oil are distinguished. However, oil is the most common mixed type. In addition to hydrocarbons, oil contains impurities of organic oxygen and sulfur compounds, as well as water and calcium and magnesium salts dissolved in it. In total, oil contains about 100 different compounds. Oil also contains mechanical impurities – sand and clay.
D.I. Mendeleev believed that oil is a valuable raw material for the production of many organic products.
Oil is a valuable raw material for producing high-quality motor fuels. After purification from water and other unwanted impurities, the oil is processed.
Most of the oil is used for production (90%) is used for production various types fuel and lubricants. Oil is a valuable raw material for the chemical industry. Although the portion of oil that is used to produce petrochemical products is small, these products have very great importance. Many thousands of organic compounds are obtained from petroleum distillation products. They, in turn, are used to produce thousands of products that satisfy not only basic needs modern society, but also the need for comfort. From substances extracted from oil we obtain:
Synthetic rubbers;
Plastics;
Explosives;
Synthetic fibers;
OIL AND GAS, THEIR COMPOSITION AND PHYSICAL PROPERTIES
OIL
Oil is a flammable, oily liquid, mostly dark in color, with a specific odor. In terms of chemical composition, oil is mainly a mixture of various hydrocarbons contained in it in a wide variety of combinations and determining its physical and chemical properties.
The following groups of hydrocarbons are found in oils: 1) methane (paraffin) with general formula S I N 2I + 2; 2) naphthenic with the general formula C„H 2P; 3) aromatic with a general formula
SpN 2l -v- /
The most common hydrocarbons in natural conditions are the methane series. Hydrocarbons of this series - methane CH 4, ethane C 2 H in, propane C 3 H 8 and butane C 4 Nu - at atmospheric pressure and normal temperature are in a gaseous state. They are part of petroleum gases. As pressure and temperature increase, these light hydrocarbons can partially or completely liquefy.
Pentane C 8 H 12, hexane C in H 14 and heptane C 7 H 1 in under the same conditions are in an unstable state: they easily pass from a gaseous state to a liquid state and back.
Hydrocarbons from C 8 H 18 to C 17 H sound are liquid substances.
Hydrocarbons with molecules containing more than 17 carbon atoms are classified as solids. These are paraffins and ceresins, contained in varying quantities in all oils.
The physical properties of oils and petroleum gases, as well as their qualitative characteristics, depend on the predominance of individual hydrocarbons or their various groups. Oils with a predominance of complex hydrocarbons (heavy oils) contain smaller amounts of gasoline and oil fractions. Content in oil
V, M-ANT V
large quantity resinous and paraffin compounds makes it viscous and inactive, which requires special measures to extract it to the surface and subsequent transportation.
In addition, oils are divided according to the main quality indicators - the content of light gasoline, kerosene and oil fractions.
The fractional composition of oils is determined by laboratory distillation, which is based on the fact that each hydrocarbon included in its composition has its own specific boiling point.
Light hydrocarbons have low boiling points. For example, pentane (C B H1a) has a boiling point of 36 ° C, and hexane (C 6 H1 4) has a boiling point of 69 ° C. Heavy hydrocarbons have higher boiling points and reach 300 ° C and higher. Therefore, when oil is heated, its lighter fractions boil off and evaporate first; as the temperature rises, heavier hydrocarbons begin to boil and evaporate.
If the vapors of oil heated to a certain temperature are collected and cooled, then these vapors will again turn into a liquid, which is a group of hydrocarbons that boil away from oil in a given temperature range. Thus, depending on the heating temperature of the oil, the lightest fractions - gasoline fractions - evaporate from it first, then the heavier ones - kerosene, then diesel fuel, etc.
The percentage of individual fractions in oil that boil away in certain temperature ranges characterizes the fractional composition of the oil.
Typically, in laboratory conditions, oil distillation is carried out in temperature ranges up to 100, 150, 200, 250, 300 and 350 ° C.
The simplest oil refining is based on the same principle as the laboratory distillation described above. This is the direct distillation of oil with the separation of gasoline, kerosene and diesel fractions from it under atmospheric pressure and heating to 300-350 ° C.
In the USSR there are various oils chemical composition and properties. Even oils from the same field can differ greatly from each other. However, the oils of each region of the USSR also have their own specific features. For example, oils from the Ural-Volga region usually contain significant amounts of resins, paraffin and sulfur compounds. Oils from the Embensky region are distinguished by relatively low sulfur content.
The greatest variety of composition and physical properties possess oil from the Baku region. Here, along with colorless oils in the upper horizons of the Surakhani field, consisting almost exclusively of gasoline and kerosene fractions, there are oils that do not contain gasoline fractions. In this area there are oils that do not contain tarry substances, as well as highly tarry ones. Many oils in Azerbaijan contain naphthenic acids. Most oils do not contain paraffins. In terms of sulfur content, all Baku oils are classified as low-sulfur.
One of the main indicators of the commercial quality of oil is its density. The density of oil at a standard temperature of 20° C and atmospheric pressure ranges from 700 (gas condensate) to 980 and even 1000 kg/m 3 .
In field practice, the density of crude oil is used to roughly judge its quality. Light oils with a density of up to 880 kg/m 3 are the most valuable; they tend to contain more gasoline and oil fractions.
The density of oils is usually measured with special hydrometers. The hydrometer is a glass tube with an expanded lower part, which contains mercury thermometer. Due to the significant weight of mercury, the hydrometer takes a vertical position when immersed in oil. In the upper narrow part of the hydrometer there is a scale for measuring density, and in the lower part there is a temperature scale.
To determine the density of oil, a hydrometer is lowered into a vessel with this oil and the value of its density is measured along the upper edge of the formed meniscus.
In order to bring the resulting measurement of oil density at a given temperature to standard conditions, i.e., to a temperature of 20 ° C, it is necessary to introduce a temperature correction, which is taken into account by the following formula:
р2о = Р* + в(<-20), (1)
where p 20 is the desired density at 20° C; p/ - density at measurement temperature I; A- coefficient of volumetric expansion of oil, the value of which is taken from special tables; she