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Oil gas. Associated petroleum gas: composition, methods of production, utilization

Features of natural gas.

1. Main component natural gas – methane.

2. In addition to methane, natural gas ethane, propane, butane are present.

3. Generally, the higher the molecular weight of the hydrocarbon, the less of it is found in natural gas.

4. The composition of natural gas from different fields is not the same. Average composition its (as a percentage by volume) is as follows: a) CH 4 – 80–97; b) C 2 H 6 – 0.5–4.0; c) C 3 H 8 – 0.2–1.5.

5. As a fuel, natural gas has great advantages over solid and liquid fuels.

6. Its heat of combustion is much higher; when burned, it leaves no ash.

7. Combustion products are much cleaner environmentally.

8. Natural gas is widely used in thermal power plants, factory boiler plants, and various industrial furnaces.

Methods of using natural gas

1. Combustion of natural gas in blast furnaces can reduce coke consumption, reduce the sulfur content in cast iron and significantly increase furnace productivity.

2. Use of natural gas in the household.

3. Currently, it is beginning to be used in vehicles (in high-pressure cylinders), which saves gasoline, reduces engine wear and, thanks to more complete combustion of fuel, keeps the air cleaner.

4. Natural gas – important source raw materials for the chemical industry, and its role in this regard will increase.

5. Hydrogen, acetylene, and soot are produced from methane.

Associated petroleum gas (features):

1) associated petroleum gas is also natural gas in origin; 2) 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”; 3) when oil is extracted to the surface, it is separated from it due to a sharp drop in pressure.

Methods of using associated petroleum gas.

1. Previously, associated gas was not used and was immediately flared in the field.

2. It is now being increasingly captured because, like natural gas, it is a good fuel and a valuable chemical feedstock.

3. Possibility of use associated gas even much wider than natural; Along with methane, it contains significant amounts of other hydrocarbons: ethane, propane, butane, pentane.

32. Oil and its processing

The industry produces the petroleum products needed by the national economy.

Natural oil always contains water, mineral salts and various kinds mechanical impurities.

Therefore, before entering processing, natural oil undergoes dehydration, desalting and a number of other preliminary operations.

Peculiarities of oil distillation.

1. The method of obtaining petroleum products by distilling one fraction after another from oil, similar to how this is done in the laboratory, is unacceptable for industrial conditions.

2. It is very unproductive, requires high costs and does not provide a sufficiently clear distribution of hydrocarbons into fractions in accordance with their molecular weight.

Free from all these shortcomings method of distilling oil in continuously operating tubular plants:

1) the installation consists of a tubular furnace for heating oil and a distillation column, where oil is separated into fractions (distillates) - separate mixtures of hydrocarbons in accordance with their boiling points - gasoline, naphtha, kerosene, etc.;

2) in a tube furnace there is a long pipeline located in the form of a coil;

3) the furnace is heated by burning fuel oil or gas;

4) oil is continuously supplied through the pipeline, where it is heated to 320–350 °C and enters the distillation column in the form of a mixture of liquid and vapor.

Features of the distillation column.

1. Distillation column – a steel cylindrical apparatus about 40 m high.

2. It has several dozen horizontal partitions with holes inside, the so-called plates.

3. Oil vapor entering the column rises up and passes through the holes in the plates.

4. Gradually cooling as they move upward, they liquefy on certain plates depending on the boiling point.

5. Less volatile hydrocarbons are liquefied already on the first plates, forming a gas oil fraction, more volatile hydrocarbons are collected higher and form a kerosene fraction, the naphtha fraction is collected even higher, the most volatile hydrocarbons exit the column in the form of vapors and form gasoline.

6. Some of the gasoline is fed back into the reflux column, which helps cool and condense the rising vapors.

7. The liquid part of the oil entering the column flows down through the plates, forming fuel oil.

To facilitate the evaporation of volatile hydrocarbons retained in the fuel oil, superheated steam is supplied from below towards the flowing fuel oil.

8. The resulting fractions at certain levels are removed from the column.

GAS APPLICATION

Gas can be found in nature in three types of deposits: gas, gas-oil and gas-condensate.

In deposits of the first type - gas - gas forms huge natural underground accumulations that do not have a direct connection with oil fields.

In the second type of deposits - gas-oil - gas accompanies oil or oil accompanies gas. Gas-oil deposits, as indicated above, are of two types: oil with a gas cap (the main volume of which is occupied by oil) and gas with an oil rim (the main volume is occupied by gas). Each gas-oil deposit is characterized by a gas factor - the amount of gas (in m3) per 1000 kg of oil.

Gas condensate deposits are characterized high pressure(more than 3–10 7 Pa) and high temperatures(80–100°C and above) in the reservoir. Under these conditions, hydrocarbons C 5 and higher pass into gas, and when the pressure decreases, condensation of these hydrocarbons occurs - the process of reverse condensation.

The gases of all the deposits considered are called natural gases, in contrast to associated petroleum gases, dissolved in oil and released from it during production.

Natural gases

Natural gases consist mainly of methane. Along with methane, they usually contain ethane, propane, butane, small quantity pentane and higher homologues and minor amounts of non-hydrocarbon components: carbon dioxide, nitrogen, hydrogen sulfide and inert gases (argon, helium, etc.).

Carbon dioxide, which is usually present in all natural gases, is one of the main products of the transformation in nature of the organic starting material of hydrocarbons. Its content in natural gas is lower than would be expected based on the mechanism chemical transformations organic residues in nature, since carbon dioxide - active ingredient, it passes into formation water, forming bicarbonate solutions. As a rule, the carbon dioxide content does not exceed 2.5%. The nitrogen content, also usually present in natural ones, is associated either with the ingress of atmospheric air or with the decomposition reactions of proteins of living organisms. The amount of nitrogen is usually higher in cases where the formation of the gas field occurred in limestone and gypsum rocks.

A special place among some natural gases occupies helium. Helium is often found in nature (in air, natural gas, etc.), but in limited quantities. Although the content of helium in natural gas is small (up to a maximum of 1–1.2%), its isolation turns out to be profitable due to the large deficit of this gas, as well as due to the large volume of natural gas production.

Hydrogen sulfide, as a rule, is absent in gas deposits. The exception is, for example, the Ust-Vilyui deposit, where the H 2 S content reaches 2.5%, and some others. Apparently, the presence of hydrogen sulfide in the gas is related to the composition of the host rocks. It has been noted that gas in contact with sulfates (gypsum, etc.) or sulfites (pyrite) contains relatively more hydrogen sulfide.

Natural gases, containing mainly methane and having a very small content of homologues C 5 and higher, are classified as dry or lean gases. The vast majority of gases produced from gas deposits are dry. Gas from gas condensate deposits is characterized by a lower content of methane and a higher content of its homologues. Such gases are called fatty or rich. In addition to light hydrocarbons, the gases of gas-condensate deposits also contain high-boiling homologues, which are released in liquid form (condensate) when the pressure decreases. Depending on the depth of the well and the pressure at the bottom, hydrocarbons may be in the gaseous state, boiling at 300–400°C.

Gas from gas condensate deposits is characterized by the content of precipitated condensate (in cm 3 per 1 m 3 of gas).

The formation of gas condensate deposits is due to the fact that at high pressures the phenomenon of reverse dissolution occurs - the reverse condensation of oil into compressed gas. At pressures of about 75×10 6 Pa, oil dissolves in compressed ethane and propane, the density of which is significantly higher than the density of oil.

The composition of condensate depends on the operating mode of the well. Thus, while maintaining a constant reservoir pressure, the quality of the condensate is stable, but when the pressure in the reservoir decreases, the composition and quantity of the condensate changes.

The composition of stable condensates of some fields has been well studied. Their boiling point is usually no higher than 300°C. By group composition: the majority are methane hydrocarbons, slightly less are naphthenic and even less are aromatic. The composition of gases from gas condensate fields after condensate separation is close to the composition of dry gases. The density of natural gas relative to air (air density is taken as unity) ranges from 0.560 to 0.650. Heat of combustion is about 37700–54600 J/kg.

Associated (petroleum) gases

Associated gas is not all the gas in a given deposit, but gas dissolved in oil and released from it during production.

Upon exiting the well, oil and gas pass through gas separators, in which associated gas is separated from unstable oil, which is sent for further processing.

Associated gases are valuable raw materials for industrial petrochemical synthesis. They do not differ qualitatively in composition from natural gases, but the quantitative difference is very significant. The methane content in them may not exceed 25–30%, but it is much higher than its homologues - ethane, propane, butane and higher hydrocarbons. Therefore, these gases are classified as fatty gases.

Due to the difference in the quantitative composition of associated and natural gases, their physical properties are different. The density (in air) of associated gases is higher than natural gases - it reaches 1.0 or more; their calorific value is 46,000–50,000 J/kg.

Gas Application

One of the main areas of application of hydrocarbon gases is their use as fuel. The high calorific value, convenience and cost-effectiveness of use undoubtedly place gas in one of the first places among other types of energy resources.

Another important view the use of associated petroleum gas - its topping, i.e. the extraction of gas gasoline from it at gas processing plants or installations. The gas is subjected to strong compression and cooling using powerful compressors, while vapors of liquid hydrocarbons condense, partially dissolving gaseous hydrocarbons (ethane, propane, butane, isobutane). A volatile liquid is formed - unstable gas gasoline, which is easily separated from the rest of the non-condensable mass of gas in the separator. After fractionation - separation of ethane, propane, and part of the butanes - a stable gas gasoline is obtained, which is used as an additive to commercial gasoline, increasing their volatility.

Propane, butane, and isobutane released during the stabilization of gas gasoline in the form of liquefied gases pumped into cylinders are used as fuel. Methane, ethane, propane, butanes also serve as raw materials for petroleum chemical industry.

After separation of C 2 -C 4 from associated gases, the remaining exhaust gas is close in composition to dry. In practice, it can be considered as pure methane. Dry and exhaust gases, when burned in the presence of small amounts of air in special installations, form a very valuable industrial product - gas soot:

CH 4 + O 2 à C + 2H 2 O

It is mainly used in the rubber industry. By passing methane with water vapor over a nickel catalyst at a temperature of 850°C, a mixture of hydrogen and carbon monoxide is obtained - “synthesis gas”:

CH 4 + H 2 O à CO + 3H 2

When this mixture is passed over a FeO catalyst at 450°C, carbon monoxide is converted to dioxide and additional hydrogen is released:

CO + H 2 O à CO 2 + H 2

The resulting hydrogen is used for the synthesis of ammonia. When methane and other alkanes are treated with chlorine and bromine, substitution products are obtained:

1. CH 4 + Cl 2 à CH 3 C1 + HCl - methyl chloride;

2. CH 4 + 2C1 2 à CH 2 C1 2 + 2HC1 - methylene chloride;

3. CH 4 + 3Cl 2 à CHCl 3 + 3HCl - chloroform;

4. CH 4 + 4Cl 2 à CCl 4 + 4HCl - carbon tetrachloride.

Methane also serves as a raw material for the production of hydrocyanic acid:

2CH 4 + 2NH 3 + 3O 2 à 2HCN + 6H 2 O, as well as for the production of carbon disulfide CS 2, nitromethane CH 3 NO 2, which is used as a solvent for varnishes.

Petroleum gas is a gas that is dissolved in oil under reservoir conditions. Such gas is obtained during the development of oil deposits due to a decrease in reservoir pressure. It is reduced to a level below the oil saturation pressure. The volume of petroleum gas (m3/t) in oil, or as it is also called the gas factor, can range from 3-5 in the upper horizons to 200-250 in deep layers, if the deposits are well preserved.

Associated petroleum gas

Oil gas fields are oil fields. Associated petroleum gas (APG) is a natural hydrocarbon gas, or rather a mixture of gases and vaporous hydrocarbon and non-hydrocarbon components that are dissolved in oil or are located in the “caps” of oil and gas condensate fields.
In fact, APG is a by-product of oil production. At the very beginning of oil production, associated petroleum gas, due to imperfect infrastructure for its collection, preparation, transportation and processing, as well as the lack of consumers, was simply flared.
One ton of oil can contain from 1-2 m3 to several thousand m3 of oil gas, it all depends on the region of production.

Use of petroleum gases

Associated petroleum gas is an important raw material for the energy and chemical industries. Such gas has an increased calorific value, which can range from 9 thousand to 15 thousand Kcal/m3. However, its use in power generation is complicated by its unstable composition and the presence of many impurities. Therefore, additional costs are required for gas purification (“drying”).
In the chemical industry, methane and ethane contained in associated gas are used to produce plastics and rubber, while heavier components are used as raw materials for the creation of aromatic hydrocarbons, fuel additives with a high octane number and liquefied hydrocarbon gases, namely liquefied propane-butane technical (SPBT).
According to the Ministry natural resources and Ecology of the Russian Federation (MPR), of the 55 billion m3 of associated gas that is produced every year in Russia, only 26% (14 billion m3) is processed. Another 47% (26 billion m3) goes to the needs of industries or is written off as technological losses, and another 27% (15 billion m3) is flared. Experts' estimates suggest that the combustion of associated petroleum gas causes a loss of almost 139.2 billion rubles, which could have been obtained from the sale of liquid hydrocarbons, propane, butane and dry gas.

Oil gas flaring problem

This process is the cause of large-scale emissions of solid pollutants, as well as a general deterioration of the environmental situation in oil-producing regions. During the process of “technological losses” and APG combustion, carbon dioxide and active soot enter the atmosphere.
Due to gas flaring in Russia, approximately 100 million tons of CO2 emissions are recorded each year (if the entire volume of gas is flared). At the same time, Russian flares are notorious for their inefficiency, that is, not all of the gas burns in them. It turns out that methane enters the atmosphere, which is much more dangerous greenhouse gas than carbon dioxide.
The amount of soot emissions during the combustion of oil gas is estimated at approximately 0.5 million tons annually. Combustion of petroleum gas is associated with thermal pollution environment. Near the torch, the radius of thermal destruction of the soil is 10-25 meters, and flora- from 50 to 150 meters.
The high concentration in the atmosphere of combustion products of such gas, namely nitrogen oxide, sulfur dioxide, carbon monoxide, causes an increase in the incidence of lung and bronchial cancer in the local population, as well as liver damage and gastrointestinal tract, nervous system, vision.
The most correct and effective method The utilization of associated petroleum gas can be called its processing at gas processing plants with the formation of dry stripped gas (DSG), a wide fraction of light hydrocarbons (NGL), as well as liquefied gases (LPG) and stable gas gasoline (SGB).
Proper utilization of oil gas will make it possible to produce about 5-6 million tons of liquid hydrocarbons, 3-4 billion m3 of ethane, 15-20 billion m3 of dry gas or 60-70 thousand GWh of electricity every year.
It is interesting that on January 1, 2012, the Decree of the Government of the Russian Federation “On measures to stimulate the reduction of air pollution from products of combustion of associated petroleum gas in flares” came into force. This document states that mining enterprises must recycle 95% of APG.

Petroleum gas composition

The composition of petroleum gas may vary. What does it depend on? Experts identify the following factors influencing the composition of petroleum gas:

Composition of oil in which gas is dissolved
conditions of occurrence and formation of deposits that are responsible for the stability of natural oil and gas systems
possibility of natural degassing.

Most associated gases, depending on the region of production, may even contain non-hydrocarbon components, for example, hydrogen sulfide and mercaptans, carbon dioxide, nitrogen, helium and argon. If hydrocarbons predominate in the composition of petroleum gases (95-100%), they are called hydrocarbons. There are also gases mixed with carbon dioxide (CO2 from 4 to 20%), or nitrogen (N2 from 3 to 15%). Hydrocarbon-nitrogen gases contain up to 50% nitrogen. Based on the ratio of methane and its homologues, the following are distinguished:

dry (methane more than 85%, C2H6 + higher 10-15%)
fatty (CH4 60-85%, C2H6 + higher 20-35%).

Based on geological characteristics, associated gases from gas caps are released, as well as gases that are dissolved directly in oil. In the process of opening up oil reservoirs, gas from oil caps most often begins to gush out. Further, the main volume of APG produced is made up of gases that are dissolved in oil.
Gas from gas caps, also called free gas, has a “lighter” composition. It contains a smaller amount of heavy hydrocarbon gases, which compares favorably with gas dissolved in oil. It turns out that the first stages of field development often have large annual volumes of APG production with a predominance of methane in its composition.
However, over time, the production of associated petroleum gas decreases, and the volume of heavy components increases.
To find out how much gas is contained in a certain oil and what its composition is, specialists carry out degassing of an oil sample taken at the wellhead or in reservoir conditions using a deep sampler. Due to incomplete degassing of oils in the bottomhole zone and riser pipes, oil gas taken from the wellhead contains a higher amount of methane and a smaller volume of its homologues, compared to gas from deep oil samples.

Composition of associated petroleum gas from various fields in Western Siberia

Region Field	Gas composition, wt.%
CH 4	C 2 H 6	C 3 H 8	i-C 4 N 10	n-С 4 Н 10	i-C 5 N 12	n-C 5 N 12	CO 2	N 2
W ESTERN SIBERIA
Samotlorskoe	60,64	4,13	13,05	4,04	8,6	2,52	2,65	0,59	1,48
Varieganskoe	59,33	8,31	13,51	4,05	6,65	2,2	1,8	0,69	1,51
B ash k o r t o s t a n
Arlanskoe	12,29	8,91	19,6	10,8	6,75	0,86	42,01
Vyatskoe	8,2	12,6	17,8	10,4	4,0	1,7	46,2
Udmurt Republic
Lozolyuksko-Zurinskoe	7,88	16,7	27,94	3,93	8,73	2,17	1,8	1,73	28,31
Arkhangelskoe	10,96	3,56	12,5	3,36	6,44	2,27	1,7	1,28	56,57
Perm region
Kuedinskoye	32,184	12,075	13,012	1,796	3,481	1,059	0,813	0,402	33,985
Krasnoyarsk	44,965	13,539	13,805	2,118	3,596	1,050	0,838	1,792	17,029
Gondyrskoye	21,305	20,106	19,215	2,142	3,874	0,828	0,558	0,891	29,597
Stepanovskoye	40,289	15,522	12,534	2,318	3,867	1,358	0,799	1,887	20,105

Liquefied Petroleum Gas

Full characterization of petroleum gases in a liquefied state makes it possible to use them as a high-quality, complete fuel for automobile engines. The main components of liquefied petroleum gas are propane and butane, which are by-products oil production or refining at gas and gasoline enterprises.
The gas combines perfectly with air to form a homogeneous combustible mixture, which guarantees a high heat of combustion and also avoids detonation during the combustion process. Gas contains minimum quantity components that contribute to carbon formation and contamination of the power system, and also cause corrosion.
The composition of liquefied petroleum gas makes it possible to create the motor properties of gas fuel.
By mixing propane, a suitable saturated vapor pressure can be achieved in gas mixture what has great value for the use of gas-cylinder vehicles in different climatic conditions. It is for this reason that the presence of propane is very desirable.
Liquefied petroleum gas has no color or odor. Because of this, to guarantee safe use in cars, it is given a special aroma - odorized.

The remaining associated gas, which oil producing companies do not flare or inject into the reservoir, ends up for processing. It needs to be cleaned before it can be transported to a processing plant. Gas freed from mechanical impurities and water is much easier to transport. In order to prevent the precipitation of liquefied fractions into the cavity of gas pipelines and to facilitate the mixture, heavy hydrocarbons are filtered out.
By removing sulfur elements, the corrosive effect of associated petroleum gas on the pipeline wall can be prevented, and by extracting nitrogen and carbon dioxide, the volume of the mixture that is not used in processing can be reduced. Purify gas various methods. Upon completion of cooling and compression (compression under pressure) of the gas, you can begin to separate it or process it using gas-dynamic methods. These methods are quite inexpensive, but they do not make it possible to isolate carbon dioxide and sulfur components from oil gas.
If sorption methods are used, then in addition to the removal of hydrogen sulfide, drying of water and wet hydrocarbon components is also carried out. The only drawback of this method is the poor adaptation of the technology to field conditions, which causes a loss of approximately 30% of the gas volume. In addition, to remove liquid, the glycol drying method is used, but only as a secondary process, because besides water, it does not release anything else from the mixture.
All of these methods can be called obsolete today. Most modern method is membrane cleaning. This method is based on the difference in the rate of penetration of different components of petroleum gas through membrane fibers.
When gas enters a processing plant, it is separated into base fractions by low-temperature absorption and condensation. Some of these fractions immediately become final products. After separation, stripped gas is obtained, which contains methane and an admixture of ethane, as well as a wide fraction of light hydrocarbons (NGL). Such gas is easily transported through pipeline systems and used as fuel, and also serves as a raw material for the production of acetylene and hydrogen. Also, using gas processing, liquid propane-butane for automobiles is produced (i.e. gas engine fuel), as well as aromatic hydrocarbons, narrow fractions and stable gas gasoline.
Associated petroleum gas, despite the extremely low profitability of its processing, is actively used in the fuel and energy industry and the petrochemical industry.

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 the 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 different high concentration and is focused on areas with the largest and most profitable deposits. 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 region (6 billion m 3) and in the 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 significance 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. Latest time goes by 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 component of this gas. In addition to methane, natural gas contains its closest homologues - ethane, propane, butane. The higher the molecular weight of the hydrocarbon, the less of it is usually found 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 also contains significant amounts of 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 (PNG) - a mixture of various gaseous hydrocarbons dissolved in oil; they are released during the extraction and distillation process (these are the so-called associated gases, mainly composed of propane and butane isomers). Petroleum gases also include petroleum cracking gases, consisting of saturated and unsaturated (ethylene, acetylene) hydrocarbons. Petroleum gases are used as fuel and to produce various chemicals. From petroleum gases, propylene, butylenes, butadiene, etc. are obtained through chemical processing, which are used in the production of plastics and rubbers.

Compound

Associated petroleum gas is a mixture of gases released from hydrocarbons of any phase state, consisting of methane, ethane, propane, butane and isobutane, containing high molecular weight liquids dissolved in it (from pentanes and higher in the homologous series) and impurities of various compositions and phase states.

Approximate composition of APG

Receipt

APG is a valuable hydrocarbon component released from mined, transported and processed hydrocarbon-containing minerals at all stages of the investment life cycle before the sale of finished products to the final consumer. Thus, the peculiarity of the origin of associated petroleum gas is that it is released at any stage from exploration and production to final sale, from oil, gas, (other sources are omitted) and in the process of their processing from any incomplete product state to any of the numerous final products.

A specific feature of APG is usually the low consumption of the resulting gas, from 100 to 5000 Nm³/hour. The content of hydrocarbons C3 + can vary in the range from 100 to 600 g/m³. At the same time, the composition and quantity of APG is not a constant value. Both seasonal and one-time fluctuations are possible ( normal change values up to 15%).

The gas from the first separation stage is usually sent directly to the gas processing plant. Significant difficulties arise when trying to use gas with a pressure of less than 5 bar. Until recently, such gas in the vast majority of cases was simply flared, however, now, due to changes in state policy in the field of APG utilization and a number of other factors, the situation is changing significantly. In accordance with the Decree of the Government of Russia dated January 8, 2009 No. 7 “On measures to stimulate the reduction of atmospheric air pollution by products of combustion of associated petroleum gas in flares”, a target indicator for flaring of associated petroleum gas was established in the amount of no more than 5 percent of the volume of produced associated petroleum gas oil gas. At the moment, the volumes of extracted, utilized and flared APG cannot be estimated due to the lack of gas metering stations at many fields. But according to rough estimates, this is about 25 billion m³.

Disposal routes

The main ways of APG utilization are processing at gas processing plants, generating electricity, burning for own needs, injection back into the reservoir to enhance oil recovery (maintaining reservoir pressure), injection into production wells - the use of “gas lift”.

APG utilization technology

Gas flare in the Western Siberian taiga in the early 1980s

The main problem in the utilization of associated gas is high content heavy hydrocarbons. Today, there are several technologies that improve the quality of APG by removing a significant portion of heavy hydrocarbons. One of them is the preparation of APG using membrane units. When using membranes, the methane number of gas increases significantly, the lowest calorific value(LHV), heat equivalent and dew point temperature (both hydrocarbon and water) are reduced.

Membrane hydrocarbon units can significantly reduce the concentration of hydrogen sulfide and carbon dioxide in the gas flow, which allows them to be used to purify gas from acidic components.

Design

Gas flow distribution diagram in the membrane module

By its design, the hydrocarbon membrane is a cylindrical block with permeate, product gas outlets and an APG inlet. Inside the block there is a tubular structure of selective material that allows only certain type molecules. General scheme flow inside the cartridge is shown in the figure.

Operating principle

The installation configuration in each specific case is determined specifically, since original composition PNG can vary greatly.

Installation diagram in basic configuration:

Pressure scheme for APG preparation

Vacuum scheme for APG preparation

Pre-separator for cleaning from coarse impurities, large droplets of moisture and oil,
Receiver at the input,
Compressor,
Refrigerator for additional cooling of gas to a temperature of +10 to +20 °C,