Natural gas

Natural gas is a mixture of gases formed in the bowels of the Earth during anaerobic decomposition organic matter.

Natural gas belongs to minerals. Natural gas in reservoir conditions (conditions of occurrence in the bowels of the earth) is in a gaseous state - in the form of separate accumulations (gas deposits) or in the form of a gas cap of oil and gas fields, or in a dissolved state in oil or water. Under standard conditions (101.325 kPa and 20°C) natural gas is only in the gaseous state. Also, natural gas can be in a crystalline state in the form of natural gas hydrates.

Sir Humphrey Davy (chemist) as early as 1813 concluded from his analyzes that firedamp is a mixture of methane CH4 with a small amount of nitrogen N2 and carbon dioxide CO 2 - that is, that it is qualitatively identical in composition with the gas released from the swamps.

The main part of natural gas is methane (CH4) - from 92 to 98%. The composition of natural gas may also include heavier hydrocarbons - methane homologues:

• ethane (C2H6),
• propane (C3H8),
• butane (C4H10).

As well as other non-hydrocarbon substances:

• hydrogen (H2),
• hydrogen sulfide (H2S),
• carbon dioxide (CO2),
• nitrogen (N2),
• helium (He)

Pure natural gas is colorless and odorless. To facilitate the possibility of determining a gas leak, odorants are added to it in a small amount - substances that have a sharp bad smell(rotten cabbage, rotten hay, rotten eggs). The most commonly used odorant is thiols, such as ethyl mercaptan (16 g per 1000 cubic meters of natural gas).

Huge deposits of natural gas are concentrated in the sedimentary shell of the earth's crust. According to the theory of the biogenic (organic) origin of oil, they are formed as a result of the decomposition of the remains of living organisms. It is believed that natural gas is formed in the sedimentary shell at higher temperatures and pressures than oil. Consistent with this is the fact that gas fields are often deeper than oil fields.

Huge reserves of natural gas are possessed by Russia (Urengoyskoye field), Iran, most of the countries of the Persian Gulf, the USA, Canada. Of the European countries, it is worth noting Norway, the Netherlands. Among the former republics Soviet Union Turkmenistan, Azerbaijan, Uzbekistan, as well as Kazakhstan (Karachaganak field) own large gas reserves

In the second half of the 20th century at the University of I. M. Gubkin discovered natural gas hydrates (or methane hydrates). Later it turned out that natural gas reserves in given state are huge. They are located both underground and in a slight depression under the seabed.

Methane and some other hydrocarbons are widely distributed in space. Methane is the third most abundant gas in the universe, after hydrogen and helium. In the form of methane ice, it is involved in the structure of many planets and asteroids distant from the sun, however, such accumulations, as a rule, are not classified as natural gas deposits, and they have not yet been found. practical application. A significant amount of hydrocarbons is present in the Earth's mantle, but they are also of no interest.

Application of natural gas

Natural gas is widely used as a fuel in residential, private and apartment buildings for heating, heating water and cooking; as a fuel for cars (gas-fuel system of a car), boiler houses, thermal power plants, etc. Now it is used in the chemical industry as a feedstock for the production of various organic substances, such as plastics. In the 19th century, natural gas was used in the first traffic lights and for lighting (gas lamps were used)

Oil and natural gas, like coal, are found in sedimentary rocks and consist mainly of chemical compounds called hydrocarbons. The oil and gas components, which were among the first to form, have high molecular weights, similar to those of the components of the solid material from which they originated, and are very viscous oils. As temperature and pressure increase, large molecules are continuously broken down into lighter and more mobile molecules. However, elementary chemical composition oil and natural gas did not change much and remained within a relatively narrow range of chemical mixtures (see table)

The energy equivalent of the estimated potential oil resources is 1.5·10 22 J and gas 1.1·10 22 J. (Data of the World Energy Conference).

A number of important conclusions can be drawn from the available information about oil and gas resources.

First, the resources of oil and gas, as well as coal, are spread over the globe very uneven.

Secondly, the regions that are now the main producers of oil and gas also have the greatest potential for new discoveries.

Thirdly, while maintaining the current rate of growth in consumption, all oil and gas resources may run out in a few decades.

When oil is pumped out of a well, at least 60% of its original amount remains in the subsoil. Especially thick oil is called heavy or more commonly - bitumen, tar. Many tars are so viscous that they can only be extracted by the mine method with subsequent processing on the surface. Quite large deposits of tar sands have been discovered (Canada, USA, CIS, Venezuela). According to many experts, the potential of heavy oil and tar sands will be approximately equal to the potential of crude oil together with natural gas, but fundamentally new, more energy-intensive technologies for their production will be required.

The following oil and gas regions can be distinguished on the territory of Ukraine:

Vostochny (Dneprovsko-Donetsk depression and north-western part of Donbass;

Western (Volynsko-Podilsky plate, Carpathian and Transcarpathian);

Southern (Black Sea region, Crimea and the boundaries of the exclusive (maritime) economic zones of the Black and Azov Seas).

The state balance of Ukraine takes into account the reserves of oil, gas and gas condensate for 323 fields: 138,283 thousand tons of oil, 1,117,936 million m 3 of gas and 79,483 thousand tons of condensate. The main number of deposits (191 pieces) are located in Eastern region, 9 - in the Western, 36 - in the Southern.

Annual production of hydrocarbons for last years an average of 4 million tons. oil and condensate 18-20 billion m 3 of gas, which is approximately 10 and 20% of the country's needs, respectively.

An unresolved problem is the increase in oil recovery. At the fields of the Dnieper-Donetsk depression, the level of oil recovery reached only 30% against 45.5% of the design, and in the Precarpathian trough 16.4 and 22.6%, respectively. The volume of residual geological oil reserves in Ukraine is more than 800 million tons. An increase in recovery by only 1% makes it possible to obtain an additional 8 million tons of oil. It should be noted that Ukraine owns huge volumes of unconventional sources of hydrocarbons. So the volume of the mine method is 11 trillion. m 3, natural gas from gas hydrota of the Black Sea 7-10 trillion. m 3.

One of the fossil fuels is oil shale, the resources of which exceed even coal, although most of them are unlikely to be developed. If organic material contained in all the world's shale, converted and used as fuel, such resources could provide at least 10 26 J of energy, and possibly more.

During the processing of shale, energy is used for their extraction and heating. The processing of 1 ton of oil shale will require as much energy as it is obtained by burning 40 liters. oil or an equivalent amount of gas, so conventional shale cannot be considered as a potential energy resource until new methods are found or old ways of extracting energy from these rocks are improved. Of undoubted interest are only those shales that, when processing 1 ton of raw materials, can produce more than 40 liters of oil equivalent.

Large deposits of such shales, located in Estonia, give 320 liters. oil equivalent per 1 ton of raw materials.

The total potential resources of oil shale in the world are estimated at 650 trillion. tons (26 trillion tons of shale resin). The main resources - about 430 - 450 trillion tons (24-25 trillion tons of shale resin) are concentrated in the USA (Colorado, Utah, Wyoming) and are associated with the Green River formation. There are large reserves of oil shale in Brazil, China, smaller ones in Bulgaria, Ukraine, Great Britain, Germany, France, Spain, Austria, Canada, Australia, Italy, Sweden, in the territory of the former Yugoslavia.

In Ukraine, research by definition geological structure and reserves of shale deposits continue. But also deposits such as Boltinskoye (Kirovograd region) - 3.4 billion tons, Carpathian shale deposits (1500 billion) indicate the prospects for using this non-traditional energy source. Huge reserves of slates are available at the Yuzovsky site (Kharkov and Donetsk regions).

Natural gas, the main part of which is methane (92-98%), is by far the most promising alternative fuel for cars. Natural gas can be used as fuel both in compressed (compressed) and liquefied form.

Methane- the simplest hydrocarbon, colorless gas (under normal conditions) odorless, chemical formula— CH4. Slightly soluble in water, lighter than air. When used in everyday life, industry, odorants (usually thiols) with a specific "gas smell" are usually added to methane. Methane is non-toxic and harmless to human health.

Extraction and transportation

The gas is located in the bowels of the Earth at a depth of one to several kilometers. Before the start of gas production, it is necessary to carry out geological exploration work, which allows to establish the location of deposits. Gas is produced using wells specially drilled for this purpose in one of the possible ways. Most often, gas is transported through gas pipelines. The total length of gas distribution pipelines in Russia is more than 632 thousand kilometers - this distance is almost 20 times the circumference of the Earth. Length main gas pipelines on the territory of Russia - 162 thousand kilometers.

Use of natural gas

The scope of natural gas is quite wide: it is used for space heating, cooking, water heating, the production of paints, glue, acetic acid and fertilizers. In addition, natural gas in compressed or liquefied form can be used as a motor fuel in vehicles, special and agricultural machinery, railway and water transport.

Natural gas - environmentally friendly motor fuel

90% of air pollution comes from vehicles.

Transfer of transport to environmentally friendly motor fuel - natural gas - allows to reduce emissions of soot, highly toxic aromatic hydrocarbons, carbon monoxide, unsaturated hydrocarbons and nitrogen oxides into the atmosphere.

When burning 1000 liters of liquid petroleum motor fuel, 180-300 kg of carbon monoxide, 20-40 kg of hydrocarbons, 25-45 kg of nitrogen oxides are emitted into the air together with exhaust gases. When using natural gas instead of fuel oil, the emission toxic substances in environment decreases approximately 2-3 times for carbon monoxide, for nitrogen oxides - 2 times, for hydrocarbons - 3 times, for smoke - 9 times, and the formation of soot characteristic of diesel engines is absent.

Natural gas - economical motor fuel

Natural gas is the most economical motor fuel. Required for processing minimum costs. In fact, all that needs to be done with gas before refueling a car is to compress it in a compressor. Today, the average retail price of 1 cubic meter of methane (which in terms of its energy properties is equal to 1 liter of gasoline) is 13 rubles. This is 2-3 times cheaper than gasoline or diesel fuel.

Natural gas is a safe motor fuel

The concentration* and temperature** flammability limits of natural gas are significantly higher than those of gasoline and diesel fuel. Methane is twice as light as air and quickly dissolves into the atmosphere when released.

According to the "Classification of combustible substances according to the degree of sensitivity" of the Ministry of Emergency Situations of Russia, compressed natural gas is classified as the safest, the fourth class, and propane-butane - to the second.

* The formation of an explosive concentration occurs when the content of gas vapor in the air is from 5% to 15%. IN open space the formation of an explosive mixture does not occur.
** The lower self-ignition limit of methane is 650°C.

Natural gas - technologically advanced motor fuel

Natural gas does not form deposits in the fuel system, does not wash off the oil film from the cylinder walls, thereby reducing friction and reducing
engine wear.

The combustion of natural gas does not produce solid particles and ash, which cause increased wear of engine cylinders and pistons

Thus, the use of natural gas as a motor fuel makes it possible to increase the service life of the engine by 1.5-2 times.

The table below summarizes a few facts about CNG and LNG:

Natural gas is a mixture of such gases that were formed in the bowels of the earth during the decomposition of various organic substances. Of course, the composition of natural gas should be adjusted for specific samples. However, all natural gases undoubtedly have many common substances And chemical elements in the building, as well as any natural gas has approximately the same physical composition and properties as others. We will talk about this with you.

General information

Natural gas is one of the most important minerals actively used in industry and in everyday life. Under conditions of occurrence (or, as gasmen say, in reservoir conditions), natural gas is exclusively in a gaseous state, either in the form of a so-called "gas cap" in common oil and gas fields, or in the form of gas deposits (that is, individual accumulations), or dissolved in water or oil. True, under certain conditions, natural gas can be not only in a gaseous state, but also in a solid state in the form of crystals.

Chemical composition of natural gas

As for the main substances that make up natural gas, they are methane (CH 4), carbon dioxide (CO 2) and nitrogen in the form of molecules (N 2). Almost any natural gas, whether mine or swamp, consists of these substances and elements. As for the composition of natural gas as a percentage, the main substance that makes up natural gas is certainly methane. Its share is from 90 to 98% - depending on the gas field. Natural gas also contains substances such as butane, propane, ethane (hydrocarbons, also called methane homologues, since they consist of the same chemical elements, differing only in the number of carbon and hydrogen atoms and, accordingly, in the structure of molecules). Of the non-hydrocarbon components of natural gas, we note, in addition to the already described nitrogen and carbon dioxide (carbon dioxide), hydrogen (H 2), helium (He) and hydrogen sulfide (H 2 S).

Physical properties of natural gas

First of all, we note that natural gas, which is in its pure form, is colorless and odorless. In order to determine the leakage of gas, so-called odorants or substances that have a sharp and rather unpleasant odor are added to it in small quantities: for example, thiols, among which ethyl mercaptan occupies a leading position. For 1000 cubic meters of natural gas, usually no more than 15-16 g of ethyl mercaptan is added. The density of natural gas in its gaseous state is on average 0.75 kg per cubic meter. In the crystalline state, the density reaches 400 kg per m 3. Natural gas ignites spontaneously only when high temperature- about 650 degrees Celsius. At a certain concentration of natural gas in the air (approximately 5-15%), explosions can occur. Also known is the specific heat of combustion of natural gas, which averages 35 MJ/m? or 9 Mcal/m?. When used in various internal combustion engines, natural gas has an octane rating of 120 to 130. Finally, natural gas is about 1.8 times lighter than air, so it rises when it leaks rather than pooling in lowlands.

Application of natural gas

First of all, natural gas modern world used as fuel and fuel. So, in many multi-apartment and private houses, people use natural gas for cooking, heating water, and heating. As for other uses of natural gas as a fuel, in Lately it is actively used not only as a fuel for various thermal power plants and boiler houses, but also as a fuel for the fuel systems of some cars. In addition, modern engineers and designers have even launched the production of vehicles running on natural gas - for example, buses. In the chemical industry, natural gas is used as a raw material for the manufacture of all kinds of substances - for example, various plastics and plastics. And in the early days of its production, many European and North American cities used natural gas as a street lighting and it was used even in the very first traffic lights.

Pure natural gas is colorless and odorless. In order to be able to determine the leak by smell, a small amount of substances with a strong unpleasant odor (rotten cabbage, rotten hay, rotten eggs) (the so-called odorants) is added to the gas. The most commonly used odorant is ethyl mercaptan (16 g per 1000 cubic meters of natural gas).

To facilitate the transportation and storage of natural gas, it is liquefied by cooling at elevated pressure.

Physical Properties

indicative physical characteristics(depending on the composition; under normal conditions, unless otherwise indicated):

The property of gas to be in a solid state in the earth's crust

In science long time it was believed that accumulations of hydrocarbons with a molecular weight of more than 60 reside in the earth's crust in liquid state, and lighter ones - in gaseous. However, Russian scientists A. A. Trofim4uk, N. V. Chersky, F. A. Trebin, Yu. deposits. This phenomenon was recognized as a scientific discovery and entered in the State Register of Discoveries of the USSR under No. 75 with a priority of 1961.

The gas passes into a solid state in the earth's crust, connecting with formation water at hydrostatic pressures (up to 250 atm) and relatively low temperatures(up to 295°K). Gas hydrate deposits have an incomparably higher concentration of gas per unit volume of a porous medium than in ordinary gas deposits, since one volume of water binds up to 220 volumes of gas when it passes into the hydrate state. The zones of gas hydrate deposits are concentrated mainly in the areas of permafrost distribution, as well as under the bottom of the World Ocean.

Natural gas fields

Huge deposits of natural gas are concentrated in the sedimentary shell of the earth's crust. According to the theory of the biogenic (organic) origin of oil, they are formed as a result of the decomposition of the remains of living organisms. It is believed that natural gas is formed in the sedimentary shell at higher temperatures and pressures than oil. Consistent with this is the fact that gas fields are often deeper than oil fields.

Gas is extracted from the bowels of the earth with the help of wells. Wells try to place evenly throughout the field. This is done for a uniform drop in reservoir pressure in the reservoir. Otherwise, gas flows between areas of the deposit are possible, as well as premature flooding of the deposit.

Gas comes out of the bowels due to the fact that in the reservoir it is under pressure many times higher than atmospheric pressure. Thus, the driving force is the pressure difference between the reservoir and the collection system.

See also: List of countries by gas production

The world's largest gas producers

The country
	Mining, bcm	Share of world market (%)	Mining, bcm	Share of world market (%)
the Russian Federation	647		673,46	18
United States of America	619		667	18
Canada	158
Iran	152		170	5
Norway	110		143	4
China	98
Netherlands	89		77,67	2,1
Indonesia	82		88,1	2,4
Saudi Arabia	77		85,7	2,3
Algeria	68		171,3	5
Uzbekistan	65
Turkmenistan			66,2	1,8
Egypt	63
Great Britain	60
Malaysia	59		69,9	1,9
India	53
UAE	52
Mexico	50
Azerbaijan			41	1,1
Other countries			1440,17	38,4
World gas production		100	3646	100

Preparation of natural gas for transportation

Plant for the preparation of natural gas.

Gas coming from wells must be prepared for transportation to the end user - a chemical plant, a boiler house, a thermal power plant, urban gas networks. The need for gas preparation is caused by the presence in it, in addition to the target components (different components are targeted for different consumers), also impurities that cause difficulties during transportation or use. So, water vapor contained in gas, under certain conditions, can form hydrates or, condensing, accumulate in various places (for example, a bend in a pipeline), interfering with the movement of gas; hydrogen sulfide is highly corrosive gas equipment(pipes, heat exchanger tanks, etc.). In addition to preparing the gas itself, it is also necessary to prepare the pipeline. Nitrogen plants are widely used here, which are used to create an inert atmosphere in the pipeline.

The gas is prepared various schemes. According to one of them, in the immediate vicinity of the field, a complex gas treatment unit (CGTU) is being built, where gas is cleaned and dried in absorption columns. Such a scheme has been implemented at the Urengoy field.

If the gas contains a large amount of helium or hydrogen sulfide, then the gas is processed at a gas processing plant, where helium and sulfur are isolated. This scheme has been implemented, for example, at the Orenburg field.

Natural gas transportation

Currently, the main mode of transport is pipeline. Gas at a pressure of 75 atm is pumped through pipes up to 1.4 m in diameter. As the gas moves through the pipeline, it loses potential energy, overcoming friction forces both between the gas and the pipe wall and between the gas layers, which is dissipated in the form of heat. Therefore, at certain intervals, it is necessary to build compressor stations (CS), where the gas is compressed to 75 atm and cooled. The construction and maintenance of the pipeline is very expensive, but nevertheless, it is the cheapest way of transporting gas over short and medium distances in terms of initial investment and organization.

In addition to pipeline transport, special gas carriers are widely used. These are special vessels on which gas is transported in a liquefied state in specialized isothermal tanks at a temperature of -160 to -150 °C. At the same time, the compression ratio reaches 600 times, depending on the needs. Thus, to transport gas in this way, it is necessary to stretch a gas pipeline from the field to the nearest sea coast, build a terminal on the coast, which is much cheaper than a conventional port, to liquefy gas and pump it into tankers, and the tankers themselves. The usual capacity of modern tankers is between 150,000 and 250,000 m³. This method of transportation is much more economical than pipeline, starting from distances to the consumer of liquefied gas more than 2000-3000 km, since the main cost is not transportation, but loading and unloading, but requires higher initial investments in infrastructure than pipeline. Its advantages also include the fact that liquefied gas is much safer during transportation and storage than compressed gas.

In 2004, international gas supplies through pipelines amounted to 502 billion m³, liquefied gas - 178 billion m³.

There are also other technologies for transporting gas, for example, using railway tanks.

There were also projects for the use of airships or in the gas hydrate state, but these developments were not used for various reasons.

Ecology

From an environmental point of view, natural gas is the cleanest type of fossil fuel. When it is burned, a much smaller amount is formed. harmful substances compared to other fuels. However, the burning of a huge amount of various kinds Fuels, including natural gas, have led to some slight increase in atmospheric carbon dioxide, a greenhouse gas, over the past half century. On this basis, some scientists conclude that there is a danger of a greenhouse effect and, as a result, climate warming. In this regard, in 1997, some countries signed the Kyoto Protocol to limit the greenhouse effect. As of March 26, 2009, the Protocol has been ratified by 181 countries worldwide (these countries collectively account for more than 61% of global emissions).

The next step was the implementation in the spring of 2004 of an unspoken alternative global program to accelerate the overcoming of the consequences of the techno-ecological crisis. The basis of the program was the establishment of adequate pricing for energy carriers according to their fuel calorie content. The price is determined on the basis of the cost of energy received at final consumption from the unit of measurement of the energy carrier. From August 2004 to August 2007, a ratio of $0.10 per kilowatt-hour was recommended and supported by regulators (the average cost of oil is $68 per barrel). Since August 2007, the ratio has been revalued to $0.15 per kilowatt-hour (the average cost of oil is $102 per barrel). The financial and economic crisis has made its own adjustments, but the specified ratio will be restored by regulators. The lack of control in the gas market delays the establishment of adequate pricing. average cost gas at the specified ratio - 648 dollars per 1000 m³.

Application

Natural gas bus

Natural gas is widely used as a fuel in residential, private and multi-apartment buildings for heating, water heating and cooking; as a fuel for cars (gas-fuel system of a car), boiler houses, thermal power plants, etc. Now it is used in the chemical industry as a feedstock for the production of various organic substances, such as plastics. In the 19th century, natural gas was used in the first traffic lights and for lighting (gas lamps were used)

Notes

Links

• The chemical composition of natural gas from various fields, its calorific value, density

Oil and gas complex
Geophysical exploration	Oilfield (Reservoir Modeling) | Geology of oil | Seismology | petrophysics
Oil and gas extraction methods	Drilling | Opening (oil reservoir) | Logging | Sampler | Mechanized (pump-compressor) mining (Submersible pump | Gas lift) | Underground well repair | Plasma-pulse impact | Tertiary Oil Recovery Method (Steam Injection | Chemical Injection)
Types of drilling rigs	Drilling rig | Pumping unit | Oil platform (Stationary oil platform | Free-floating offshore oil platform | Semi-submersible oil drilling platform | Mobile offshore platform with retractable legs | Drilling ship | Oil platform with extended legs | Floating oil production, storage and offloading unit)