Natural gas

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

Natural gas is classified as a mineral. Natural gas in reservoir conditions (conditions of occurrence in the earth's interior) 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 a gaseous state. Natural gas can also be in a crystalline state in the form of natural gas hydrates.

Sir Humphrey Davy (scientist-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 emitted from swamps.

The main part of natural gas is methane (CH4) - from 92 to 98%. Natural gas can also contain heavier hydrocarbons - methane homologues:

• Ethane (C2H6),
• Propane (C3H8),
• Butane (C4H10).

And also other non-hydrocarbon substances:

• Hydrogen (H2),
• Hydrogen sulfide (H2S),
• Carbon dioxide (CO2),
• Nitrogen (N2),
• Helium (Not)

Pure natural gas is colorless and odorless. To facilitate the possibility of detecting gas leakage, 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, for example 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 biogenic (organic) origin of oil, they are formed as a result of decomposition of the remains of living organisms. It is believed that natural gas forms in the sedimentary shell at higher temperatures and pressures than oil. Consistent with this is the fact that gas fields are often located deeper than oil fields.

Russia (Urengoyskoye field), Iran, most of the countries of the Persian Gulf, USA, Canada possess huge reserves of natural gas. Among the European countries, it is worth noting Norway and 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 XX century at the University. IM Gubkin discovered natural gas hydrates (or methane hydrates). Later it turned out that natural gas reserves in this state huge. They are located both underground and in a shallow depression under the seabed.

Methane and some other hydrocarbons are widespread in space. Methane is the third most common gas in the universe, after hydrogen and helium. In the form of methane ice, it participates in the structure of many planets and asteroids far from the sun, but such clusters, 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 not of interest.

Natural gas applications

Natural gas is widely used as a fuel in residential, private and apartment buildings for heating, hot water and cooking; as 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, for example, 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 are mainly composed of chemical compounds called hydrocarbons. The early oil and gas components have high molecular weights, similar to those of the solid material from which they originated, and are highly viscous oils. As the temperature and pressure rise, large molecules are continuously broken down into lighter and more mobile ones. 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 from the World Energy Conference).

From the available knowledge of oil and gas resources, a number of important conclusions can be drawn.

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.

Third, if the current rate of growth in consumption continues, all oil and gas resources may dry up 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 sticky that they can only be mined and processed at 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 extraction will be required.

On the territory of Ukraine, the following oil and gas regions can be distinguished:

Eastern (Dnieper - Donetsk depression and north - western part of Donbass;

Western (Volyn - Podolsk plate, Carpathian and Transcarpathian regions);

Southern (Black Sea region, Crimea and the borders 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 m3 of gas and 79,483 thousand tons of condensate. The main number of deposits (191 units) are located in Eastern region, 9 - in the West, 36 - in the South.

Hydrocarbon production annually for last years an average of 4 million tons. oil and condensate 18-20 billion cubic meters of gas, which is approximately 10 and 20% of the country's demand, respectively.

Increasing oil recovery remains an unsolved problem. At the fields of the Dnieper-Donetsk depression, the level of oil recovery reached only 30% against 45.5% of the design ones, and in the Ciscarpathian 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 possesses huge volumes of unconventional sources of hydrocarbons. So the volume of the mine method is 11 trillion. m 3, natural gas in the Black Sea gas reservoirs 7-10 trillion. m 3.

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

Shale processing uses energy to extract and heat them. 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 a potential energy resource until new or improved old ways of extracting energy from these rocks are found. Of undoubted interest are only those shales that, when processed 1 ton of raw materials, can yield more than 40 liters of oil equivalent.

Large deposits of such shale, 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 oil shale). The main resources - about 430 - 450 trillion tons (24-25 trillion tons of shale tar) are concentrated in the USA (states of Colorado, Utah, Wyoming) and are associated with the Green River formation. There are large reserves of oil shale in Brazil, China, smaller - in Bulgaria, Ukraine, Great Britain, Germany, France, Spain, Austria, Canada, Australia, Italy, Sweden, on the territory of the former Yugoslavia.

In Ukraine, studies by definition geological structure and the reserves of shale deposits continue. But also deposits such as Boltinskoe (Kirovograd region) - 3.4 billion tons, Carpathian shale deposits (1500 billion) speak of the prospects for using this unconventional energy source. There are huge reserves of shale at the Yuzovskaya site (Kharkiv and Donetsk regions).

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

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, in the 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

Gas is found 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, which makes it possible to establish the location of the deposits. Gas is extracted using wells specially drilled for this in one of the possible ways. Gas is transported most often 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.

Natural gas use

The field of application of natural gas is quite wide: it is used for heating premises, cooking food, heating water, producing 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 is an environmentally friendly motor fuel

90% of air pollution comes from vehicles.

Transfer of vehicles 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, emissions toxic substances in environment decreases by 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 is an economical motor fuel

Natural gas is the most economical motor fuel. Its processing requires minimum costs... Basically, all that needs to be done with the gas before refueling the car is compressing it in the 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 ** limits of ignition of natural gas are significantly higher than that of gasoline and diesel fuel. Methane is twice lighter than air and dissolves quickly in the atmosphere when released.

According to the "Classification of combustible substances by the degree of sensitivity" of the Ministry of Emergencies of Russia, compressed natural gas is assigned to the safest, fourth class, and propane-butane - to the second.

* Formation of an explosive concentration occurs when the content of gas vapors in the air is from 5% to 15%. IN open space no explosive mixture is formed.
** The lower limit of autoignition of methane is 650 ° C.

Natural gas is a technological 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 generate solid particles and ash, which cause increased wear of engine cylinders and pistons

Thus, the use of natural gas as a motor fuel can increase the engine's service life 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 earth's interior during the decomposition of various organic substances. Of course, the composition of natural gas should be determined with a correction for specific samples. However, all natural gases undoubtedly have a lot common substances and chemical elements in the structure, 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. In the conditions of occurrence (or, as gas workers 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, separate accumulations), either 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.

The 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, be it mine or bog gas, consists of these substances and elements. As for the composition of natural gas as a percentage, methane is undoubtedly the main substance in natural gas. Its share ranges from 90 to 98%, depending on the gas field. Also, natural gas 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 in its pure form is colorless and odorless. In order to detect a gas leak, so-called odorants or substances that have a pungent and rather unpleasant odor are added to it in small quantities: for example, thiols, among which ethyl mercaptan takes the leading place. Usually no more than 15-16 g of ethyl mercaptan is added per 1000 cubic meters of natural gas. The density of natural gas in the gaseous state averages 0.75 kg per cubic meter. In the crystalline state, the density reaches 400 kg per m 3. Natural gas ignites spontaneously only when very high temperature- about 650 degrees Celsius. Explosions can occur at a certain concentration of natural gas in the air (approximately 5-15%). The specific heat of combustion of natural gas is also known, averaging 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 approximately 1.8 times lighter than air, so it rises upward when leaked rather than collecting in lowlands.

Natural gas applications

First of all, natural gas in modern world used as fuel and fuel. So, in many apartment and private houses, people use natural gas for cooking, heating water, heating. As for other uses of natural gas in the form of fuel, in recent times 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 set up 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 at the dawn of its production in many European and North American cities, natural gas was used as 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 detect a leak by smell, a small amount of substances with a strong unpleasant odor (rotten cabbage, rotten hay, rotten eggs) (so-called odorants) are added to the gas. The most commonly used odorant is ethyl mercaptan (16 g per 1000 cubic meters of natural gas).

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

Physical properties

Indicative physical characteristics(depend on composition; under normal conditions, unless otherwise indicated):

The property of a gas to be solid 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.F. Makogon, V.G. Vasiliev discovered the property of natural gas under certain thermodynamic conditions to pass into a solid state in the earth's crust and form gas hydrate deposits. This phenomenon was recognized as a scientific discovery and entered into the State Register of Discoveries of the USSR under No. 75 with a priority of 1961.

Gas transforms into a solid state in the earth's crust, combining 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 gas concentration per unit volume of a porous medium than in conventional gas fields, since one volume of water, when it goes into a hydrated state, binds up to 220 gas volumes. 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 biogenic (organic) origin of oil, they are formed as a result of decomposition of the remains of living organisms. It is believed that natural gas forms in the sedimentary shell at higher temperatures and pressures than oil. Consistent with this is the fact that gas fields are often located deeper than oil fields.

Gas is extracted from the bowels of the earth using wells. They try to place the wells evenly throughout the entire territory of the field. This is done to ensure a uniform drop in reservoir pressure in the reservoir. Otherwise, gas flows between the fields of the field are possible, as well as premature flooding of the deposit.

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

See also: List of gas producing countries

The world's largest gas producers

Country
	Extraction, billion cubic meters	Share of the world market (%)	Extraction, billion cubic meters	Share of the world market (%)
the Russian Federation	647		673,46	18
USA	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 treatment is caused by the presence in it, in addition to the target components (different components are target for different consumers), as well as impurities that cause difficulties during transportation or use. So, the vapor of water contained in the gas, under certain conditions, can form hydrates or, condensing, accumulate in various places (for example, a bend in the pipeline), interfering with the movement of the gas; hydrogen sulfide is highly corrosive gas equipment(pipes, heat exchanger tanks, etc.). In addition to the preparation of 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.

Gas is prepared according to various schemes... According to one of them, in the immediate vicinity of the field, a complex gas treatment unit (CGTU) is being constructed, where gas is purified and dried in absorption columns. This scheme has been implemented at the Urengoyskoye 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 emitted. This scheme has been implemented, for example, at the Orenburg field.

Natural gas transportation

Currently, the main mode of transport is pipeline. Gas under a pressure of 75 atm is pumped through pipes with a diameter of up to 1.4 m. As the gas moves through the pipeline, it loses potential energy, overcoming the frictional 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 investments and organization.

In addition to pipeline transport, special tankers - gas carriers are widely used. These are special ships on which gas is transported in a liquefied state in specialized isothermal containers at temperatures from -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, to build a terminal on the shore, which is much cheaper than a conventional port, for liquefying gas and pumping it onto tankers, and the tankers themselves. The typical tonnage of modern tankers ranges from 150,000 to 250,000 m³. This method of transportation is much more economical than pipeline, starting with distances to the consumer of liquefied gas of more than 2000-3000 km, since the main cost is not transportation, but loading and unloading operations, 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 via pipelines amounted to 502 billion cubic meters, liquefied gas - 178 billion cubic meters.

There are also other technologies for gas transportation, for example, using rail tank cars.

There were also projects for the use of airships or in a gas hydrated state, but these developments did not find application for various reasons.

Ecology

Ecologically, natural gas is the cleanest type of fossil fuel. When it burns, a much smaller amount is formed harmful substances compared to other fuels. However, the burning by humanity of a huge amount different types fuels, including natural gas, have led to some slight increase in atmospheric carbon dioxide, which is a greenhouse gas, over the past half century. Some scientists, on this basis, conclude that there is a danger of the greenhouse effect and, as a consequence, 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 of the world (these countries together account for more than 61% of global emissions).

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

Application

Natural gas bus

Natural gas is widely used as a fuel in residential, private and apartment buildings for heating, water heating and cooking; as 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, for example, plastics. In the 19th century, natural gas was used in the first traffic lights and for lighting (gas lamps were used)

Notes (edit)

Links

• The chemical composition of natural gas from various fields, its heat of combustion, density

Oil and gas complex
Geophysical exploration	Oilfield (Reservoir Modeling) | Oil Geology | Seismology | Petrophysics
Oil and gas production methods	Drilling | Autopsy (oil reservoir) | Logging | Sampler | Mechanized (pump and compressor) production (Submersible pump | Gaslift) | Underground well repair | Plasma Pulse Impact | Tertiary oil production method (Steam injection into the reservoir | Chemical injection)
Drilling rig types	Drilling Rig | Rocking machine | Oil platform (Fixed oil platform | Free-floating offshore oil platform | Semi-submersible oil drilling platform | Mobile offshore platform with telescopic legs | Drilling ship | Extended leg oil platform | FPSO)