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Why does associated gas have this name? Associated petroleum gas: composition, methods of production, utilization

For a long time passing petroleum gas had no value. It was considered a harmful impurity during oil production and was burned directly when gas came out of an oil-bearing well. But time passed. New technologies have emerged that have allowed us to take a different look at APG and its properties.

Compound

Associated petroleum gas is located in the “cap” of the oil-bearing formation - the space between the soil and the deposits fossil oil. Also, some of it is in a dissolved state in the oil itself. Essentially, APG is the same natural gas, the composition of which is big amount impurities.

Associated petroleum gas has a wide variety of contents various kinds hydrocarbons. These are mainly ethane, propane, methane, butane. It also contains heavier hydrocarbons: pentane and hexane. In addition, petroleum gas includes a certain amount of non-flammable components: helium, hydrogen sulfide, carbon dioxide, nitrogen and argon.

It is worth noting that the composition of associated petroleum gas is extremely unstable. The same APG deposit can noticeably change the percentage of certain elements over the course of several years. This is especially true for methane and ethane. But even despite this, oil gas is highly energy-intensive. One cubic meter of APG, depending on the type of hydrocarbons that are included in its composition, is capable of releasing from 9,000 to 15,000 kcal of energy, which makes it promising for use in various economic secateurs.

The leaders in associated petroleum gas production are Iran, Iraq, Saudi Arabia, Russian Federation and other countries in which the main oil reserves are concentrated. Russia accounts for about 50 billion cubic meters of associated petroleum gas per year. Half of this volume goes to needs production areas, 25% for additional processing, and the rest is incinerated.

Cleaning

Associated petroleum gas is not used in its original form. Its use becomes possible only after preliminary cleaning. To do this, layers of hydrocarbons having different densities are separated from each other in equipment specially designed for this purpose - a multi-stage pressure separator.

Everyone knows that water in the mountains boils at a lower temperature. Depending on the altitude, its boiling point can drop to 95 ºС. This happens due to the difference atmospheric pressure. This principle is used in the operation of multi-stage separators.

Initially, the separator supplies a pressure of 30 atmospheres and after a certain period of time gradually reduces its value in steps of 2-4 atmospheres. This ensures uniform separation of hydrocarbons from different temperatures boiling from each other. Next, the resulting components are sent directly to the next stage of purification to oil refining plants.

Application of associated petroleum gas

Now it is actively in demand in some areas of production. First of all, this is - chemical industry. For her, APG serves as a material for the production of plastics and rubber.

The energy industry is also partial to the byproduct of oil production. APG is the raw material from which the following types of fuel are obtained:

Dry stripped gas.
Wide fraction of light hydrocarbons.
Gas motor fuel.
Liquefied petroleum gas.
Stable gas gasoline.
Separate fractions based on carbon and hydrogen: ethane, propane, butane and other gases.

The volume of use of associated petroleum gas would be even higher if not for a number of difficulties that arise during its transportation:

The need to remove mechanical impurities from the gas composition. When APG flows out of a well, tiny soil particles enter the gas, which significantly reduce its transport properties.
Associated petroleum gas must undergo a petroleum treatment procedure. Without this, the liquefied fraction will precipitate in the gas pipeline during its transportation.
The composition of associated petroleum gas must be purified from sulfur. Increased sulfur content is one of the main reasons for the formation of corrosion spots in the pipeline.
Removal of nitrogen and carbon dioxide to improve calorific value gas

Due to the above reasons for a long time Associated petroleum gas was not utilized, but burned directly near the well where the oil was located. It was especially good to watch this while flying over Siberia, where torches with black clouds of smoke emanating from them were constantly visible. This continued until environmentalists intervened, realizing all the irreparable harm that was being caused to nature in this way.

Consequences of burning

Gas combustion is accompanied by an active thermal effect on the environment. Within a radius of 50-100 meters from the immediate location of the fire, there is a noticeable decrease in the volume of vegetation, and at a distance of up to 10 meters there is a complete absence of vegetation. This is mainly due to burnout nutrients soils on which all kinds of trees and grasses depend so much.

A burning torch serves as a source of carbon monoxide, the same one that is responsible for the destruction of the Earth's ozone layer. In addition, the gas contains sulfur dioxide and nitrogen oxide. These elements belong to the group toxic substances for living organisms.

Thus, people living in areas with active oil production have an increased risk of developing various types of pathologies: oncology, infertility, weakened immunity, etc.

For this reason, at the end of the 2000s, the issue of APG utilization arose, which we will consider below.

Methods for utilization of associated petroleum gas

On this moment there are many options for removing oil waste without causing harm environment. The most common ones are:

Sent directly to the oil refinery. It is the most optimal solution, both from a financial and environmental point of view. But provided that there is already a developed gas pipeline infrastructure. In its absence, a significant investment of capital will be required, which is justified only in the case large deposits.
Recycling by using APG as fuel. Associated petroleum gas is supplied to power plants, where, using gas turbines it is produced from it electrical energy. The disadvantage of this method is the need to install equipment for pre-cleaning, as well as its transportation to its destination.
Injection of spent APG into the underlying oil reservoir, thereby increasing the oil recovery factor of the well. This happens due to the increase under the soil layer. This option It is characterized by ease of implementation and relatively low cost of the equipment used. There is only one drawback here - the lack of actual utilization of APG. There is only a delay, but the problem remains unresolved.

Associated petroleum gas, or APG, is gas dissolved in oil. Associated petroleum gas is produced during oil production, that is, it is, in fact, a by-product. But APG itself is a valuable raw material for further processing.

Molecular composition

Associated petroleum gas consists of light hydrocarbons. This is, first of all, methane - main component natural gas - as well as heavier components: ethane, propane, butane and others.

All these components differ in the number of carbon atoms in the molecule. So, a methane molecule contains one carbon atom, ethane has two, propane has three, butane has four, etc.

~ 400,000 tons - the carrying capacity of an oil supertanker.

According to the World Fund wildlife(WWF), in oil-producing regions up to 400,000 tons of solid pollutants are emitted into the atmosphere annually, a significant share of which is occupied by APG combustion products.

Environmentalists' fears

Associated petroleum gas must be separated from the oil in order for it to meet the required standards. For a long time, APG remained a by-product for oil companies, so the problem of its disposal was solved quite simply - by burning it.

Some time ago, flying on an airplane over Western Siberia, one could see many burning torches: it was associated petroleum gas.

In Russia, almost 100 million tons of CO 2 are generated annually as a result of gas flaring.
Soot emissions also pose a danger: according to environmentalists, tiny soot particles can be transported over long distances and deposited on the surface of snow or ice.

Even almost invisible to the eye, contamination of snow and ice significantly reduces their albedo, that is, reflectivity. As a result, the snow and ground air warm up, and our planet reflects less solar radiation.

Reflectivity of uncontaminated snow:

Changes for the better

IN Lately The situation with APG utilization began to change. Oil companies are increasingly paying attention to the problem rational use associated gas. The intensification of this process is facilitated by the Government's Russian Federation Resolution No. 7 of January 8, 2009, which sets out the requirement to bring the level of associated gas utilization to 95%. If this does not happen, oil companies face high fines.

OAO Gazprom has prepared a Medium-term investment program for increasing the efficiency of APG use for 2011–2013. The level of APG utilization across the Gazprom Group (including OJSC Gazprom Neft) in 2012 averaged about 70% (in 2011 - 68.4%, in 2010 - 64%), with IV quarter of 2012 at the fields of OJSC Gazprom the level beneficial use APG makes up 95%, and Gazprom Dobycha Orenburg LLC, Gazprom Pererabotka LLC and Gazprom Neft Orenburg LLC already use 100% APG.

Disposal options

Exists a large number of methods for the beneficial utilization of APG, but in practice only a few are used.

The main way to utilize APG is to separate it into components, most of which are dry stripped gas (essentially the same natural gas, that is, mainly methane, which may contain some amount of ethane). The second group of components is called the wide fraction of light hydrocarbons (NGL). It is a mixture of substances with two or more carbon atoms (C 2 + fraction). It is this mixture that is the raw material for petrochemicals.

The processes of separation of associated petroleum gas occur at low-temperature condensation (LTC) and low-temperature absorption (LTA) units. After separation, dry stripped gas can be transported via a conventional gas pipeline, and natural gas liquids can be supplied to further processing for the production of petrochemical products.

According to the Ministry natural resources and ecology, in 2010 the largest oil companies used 74.5% of all produced gas, and flared 23.4%.

Plants for processing gas, oil and gas condensate into petrochemical products are high-tech complexes that combine chemical production with oil refining industries. Processing of hydrocarbon raw materials is carried out at the facilities of Gazprom subsidiaries: at the Astrakhan, Orenburg, Sosnogorsk gas processing plants, the Orenburg helium plant, the Surgut condensate stabilization plant and the Urengoy condensate preparation plant for transport.

You can also use associated petroleum gas for power plants to generate electricity - this allows oil companies to solve the problem of energy supply to the fields without resorting to purchasing electricity.

In addition, APG is injected back into the reservoir, which makes it possible to increase the level of oil recovery from the reservoir. This method is called the cycling process.

Peculiarities natural gas.

1. The main component of natural gas is methane.

2. In addition to methane, natural gas contains ethane, propane, and butane.

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. Its average composition (in percent 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 is an important source of raw material 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. Before associated gas found no use and was immediately burned 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. The possibilities for using associated gas are even much wider than natural gas; 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 of mechanical impurities.

Therefore, before entering for 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, as 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.

Unlike natural gas, associated petroleum gas contains, in addition to methane and ethane, a large proportion of propanes, butanes and vapors of heavier hydrocarbons. Many associated gases, depending on the field, also contain non-hydrocarbon components: hydrogen sulfide and mercaptans, carbon dioxide, nitrogen, helium and argon.

When oil reservoirs are opened, gas from the oil caps usually begins to gush out first. Subsequently, the main part of the produced associated gas consists of gases dissolved in oil. Gas from gas caps, or free gas, is “lighter” in composition (with a lower content of heavy hydrocarbon gases) in contrast to gas dissolved in oil. Thus, the initial stages of field development are usually characterized by large annual production volumes of associated petroleum gas with a larger proportion of methane in its composition. With long-term exploitation of the field, the production of associated petroleum gas is reduced, and a large share of the gas falls on heavy components.

Injection into the subsoil to increase reservoir pressure and, thereby, the efficiency of oil production. However, in Russia, unlike a number foreign countries, this method, with rare exceptions, is not used, because it is a highly costly process.

Use locally to generate electricity for the needs of oil fields.

When significant and stable volumes of associated petroleum gas are released - use as fuel at large power plants, or for further processing.

Most effective method utilization of associated petroleum gas - its processing at gas processing plants to produce dry stripped gas (DSG), wide fraction of light hydrocarbons (NGL), liquefied gases (LPG) and stable gas gasoline (SGG).

A large consulting company in the fuel and energy sector, PFC Energy, in its study “Utilization of Associated Petroleum Gas in Russia,” noted that the optimal option for using APG depends on the size of the field. Thus, for small fields, the most attractive option is to generate electricity on a small scale for their own field needs and the needs of other local consumers.

For medium-sized fields, according to researchers, the most economically feasible option for associated petroleum gas utilization is the extraction of liquefied petroleum gas at a gas processing plant and the sale of liquefied petroleum gas (LPG) or petrochemical products and dry gas.

For large fields, the most attractive option is to generate electricity at a large power plant for subsequent wholesale sale to the power grid.

According to experts, solving the problem of associated gas utilization is not only an issue of ecology and resource conservation, it is also a potential national project worth 10-15 billion dollars. Only the utilization of APG volumes would make it possible to annually produce up to 5-6 million tons of liquid hydrocarbons, 3-4 billion cubic meters of ethane, 15-20 billion cubic meters of dry gas or 60-70 thousand GWh of electricity.

Russian President Dmitry Medvedev instructed the Russian government to take measures to end the practice of irrational use of associated gas by February 1, 2010.

Injection into the subsoil to increase reservoir pressure and, thereby, the efficiency of oil production. However, in Russia, unlike a number of foreign countries, this method, with rare exceptions, is not used, because it is a highly costly process.

Use locally to generate electricity for the needs of oil fields.

When significant and stable volumes of associated petroleum gas are released - use as fuel at large power plants, or for further processing.

The most effective way to utilize associated petroleum gas is its processing at gas processing plants to produce dry stripped gas (DSG), wide fraction of light hydrocarbons (NGL), liquefied gases (LPG) and stable gas gasoline (SGG).

For large fields, the most attractive option is to generate electricity at a large power plant for subsequent wholesale sale to the power grid.

Russian President Dmitry Medvedev instructed the Russian government to take measures to end the practice of irrational use of associated gas by February 1, 2010.

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