Oil and gas - the most important raw materials in the world.A special place in the oil and gas industry occupies the associated gas.Earlier this resource is not used.But now the attitude to this valuable natural resources has changed.
What is an associated gas
This hydrocarbon gas that is released from the wells and the reservoir of oil in the process of separation.It is a mixture of vaporized hydrocarbon and non-hydrocarbon components of natural origin.
its quantity in oil may vary from one to several thousand cubic meters in one ton.
On the specifics of obtaining associated gas is considered to be a by-product of oil production.Hence the name.Due to the lack of necessary infrastructure for gas gathering, transportation and processing of large amounts of this natural resource is lost.For this reason, most of the associated gas simply flared.
gas composition
Associated petroleum gas is composed of methane and heavier hydrocarbons - ethane, butane, propane, and so on. D. The gas composition in various oil fields may be slightly different.In some regions associated gas may contain non-hydrocarbon components - nitrogen compounds, sulfur, oxygen.
Associated gas, which gushes after opening the oil reservoirs, characterized by a smaller number of heavy hydrocarbon gases.More "heavy" on the composition of the gas is in the most oil.Therefore, in the initial stages of development of oil usually produced many associated gas rich in methane.In the operation of deposits, these figures are gradually reduced, but most of the gas make heavy components.
natural and associated petroleum gas: what is the difference
associated gas compared to natural contains less methane, but has a large number of its homologues, including pentane and hexane.Another important difference - a combination of the structural components in the different fields in which the produced associated petroleum gas.Composition APG can even vary for different periods of the same field.For comparison, the quantitative combination of components of natural gas are always constant.Therefore, APG can be used for different purposes, and natural gas is used only as an energy feedstock.
Getting APG
Associated gas produced by separation from oil.For this purpose, multistage cages with different pressures.Thus, in a first separation stage is pressurized from 16 to 30 bar.At all subsequent stages of the pressure is gradually reduced.In the last stage of production is reduced to 1.5-4 option bar.The values of temperature and pressure are determined by APG separation technology.
gas produced in the first stage, immediately sent to the gas processing plant.Great difficulties arise with the gas pressure below 5 bar.Earlier this always APG was flared, but recently changed the gas utilization policy.The government has begun to develop incentives to reduce pollution of the environment.For example, at the state level in 2009 it was set figure flaring, which shall not exceed 5% of the total production of associated gas.
Application APG industry
Earlier APG and not used immediately after getting burned.Now scientists discern the value of this natural resource and looking for ways to use it effectively.
Associated petroleum gas, whose composition is a mixture of propane, butane and heavier hydrocarbons, is a valuable raw material for the energy and chemical industries.APG has a calorific value.So, while it allocates the combustion of 9 to 15 thousand kcal / cubic meter.In its original form it is not used.Be sure to need cleaning.
In the chemical industry of the associated gas contained methane and ethane are made of plastics and rubber.Heavier hydrocarbon components used as raw materials for the production of high-octane fuel additive, aromatic hydrocarbons and liquefied petroleum gas.
In Russia, more than 80% of the associated gas produced from five companies producing oil and gas: OAO "Rosneft", "Gazprom oil", OAO "LUKOIL oil company", OAO "TNK-BP Holding" JSC"Surgutneftegaz".According to official data, the country annually produces more than 50 billion cubic meters of associated gas, of which 26% is recycled, 47% is used for industrial purposes, and the remaining 27% is flared.
There are situations that do not always cost-effective use of associated petroleum gas.The use of this resource will often depend on the size of the deposit.Thus, the gas produced in small fields, should be used to provide electricity to local consumers.On the average deposits more economically extract liquefied petroleum gas at the gas processing plant and sell it to the chemical industry.The best option for large fields is the production of electricity in large power plants, followed by the sale.
Harm from flaring
gas flaring pollute the environment.Around the torch operates thermal degradation, which affects the way in a radius of 10-25 meters and the vegetation within 50-150 meters.In the combustion process fall into the atmosphere of nitrogen and carbon monoxide, sulfur dioxide, and unburned hydrocarbons.Scientists estimate that as a result of flaring emitted about 0.5 million tonnes of soot per year.
also combustion gases are dangerous to human health.According to statistics, in the main refinery region of Russia - Tyumen region - the incidence of the population for many kinds of diseases above the average across the country.Very often people in the region suffer from respiratory pathologies.There is a growing number of tumors, diseases of the sense organs and the nervous system.
In addition, the products of combustion of APG cause diseases that manifest themselves only after a while.These include the following:
- infertility;
- miscarriage;
- hereditary diseases;
- weakened immunity;
- oncological diseases.
Technologies APG
main problem of utilization of associated gas is a high concentration of heavy hydrocarbons.In today's oil and gas industry uses more efficient technologies that enable to improve the quality of the gas by the removal of heavy hydrocarbons:
- gas fractioning division.
- adsorption technology.
- low temperature separation.
- membrane technology.
Way of associated gas utilization
There are many methods, but in practice are used only a few.The main method - utilization of associated gas by separation into components.This recycling process allows to obtain dry gas, which, in essence, is the same as natural gas and natural gas liquids (NGL).This mixture can be used as a raw material for petrochemistry.
gas separation occurs at the low temperature settings absorption and condensation.After completion of the dry gas is transported through pipelines and NGL is sent to refineries for further processing.
second effective way APG - cycling process.This method involves injecting gas back into the reservoir to increase the pressure.This solution allows you to increase the volume of oil recovery from the reservoir.
In addition, associated gas can be used to generate electricity.This will allow the oil companies to significantly save money, since eliminating the need to purchase electricity from the side.
