Associated petroleum gas, the composition, use, and recycling.
Associated petroleum gas is a mineral, a natural hydrocarbon gas dissolved in oil or in the “hats” of oil and gas condensate fields.
Associated petroleum gas is a mineral, a natural hydrocarbon gas dissolved in oil or in “caps” oil and gas condensate fields.
To refer to associated petroleum gas use the acronym APG.
In the English language associated petroleum gas is referred to as “associated petroleum gas“, abbreviated to APG. Literally means “bound, United oil gas”.
Associated petroleum gas, and natural gas, is a mixture of gases and vaporous hydrocarbon and non-hydrocarbon components.
In fact, the associated gas is the same natural gas, but with a large amount of impurities. Therefore, the physical properties associated petroleum gas similar to natural gas.
APG has no color or smell. Lighter than air 1.8 times. Flammable and explosive. If leak is not going in the lowlands, and climbs up.
Associated petroleum gas is dissolved in most of oiland is located in the space between the rock and oil deposits, referred to as “cap”. At the opening oil reservoirs usually first begins to gush gas oil caps. Subsequently, the main part of extracted APG are gases dissolved in oil.
APG is a byproduct of oil production. So, just for one ton of recoverable oil, depending on the mining area and deposits there are from 25 to 800 m3 of recoverable APG.
For a long time it was considered as a harmful impurity in the oil, APG and was simply burned at the oil production at oil wells, polluting the environment. However, not so long ago acknowledged that the oil-associated gas, though, and accompanies oil production is a valuable raw material for further processing. Therefore, the oil companies began to pay attention to the rational use of associated gas.
Associated petroleum gas is divided into:
types – the content of the target components – hydrocarbons from C3 and above: skinny, medium, bold and extra bold,
classes content the content of sulfur compounds: sulphur-free, low-sulphur, sulphur and high-sulphur,
group – the content of non-combustible components: ballastless, malabaristas, sredneoblastnoj and vysokorychlostny,
– according to content of mechanical impurities: clean, relatively clean, polluted and heavily polluted.
Associated petroleum gas as natural gas is a gaseous mixture of hydrocarbon and non-hydrocarbon components.
Its composition varies from one field to another, the nature of the field, from the stage of development of the field. In addition, one and the same field for several years can significantly change the percentage of its components. Associated petroleum gas stored in gas “caps” and retrieved at the beginning of operation field is “lighter” in composition (with a high content of methane and a smaller share of heavy hydrocarbon gases) in contrast to the dissolved oil gas. In the future, if exploitation of gas from gas caps reduced and become dissolved in oil associated gas contains a large proportion of heavy hydrocarbons.
Because associated gas is extracted from oil (or gas condensate) in its (his) separation (3 degrees), the composition of the resulting associated petroleum gas will also be different after each stage of separation.
Possible seasonal or occasional fluctuations in the composition of the APG.
Hydrocarbon components of associated petroleum gas is represented by methane CH4 and its homologues: С2Н6 ethane, propane C3H8, butane C4H10, pentane С5Н12 hexane С6Н14, С7Н16 heptane, octane С8Н18, nananom С9Н20, Dean С10Н22, etc. until proven С22Н46.
Non-hydrocarbon components of associated petroleum gas: Ar, H2, He, N2, H2S, water vapor – H2O, CO, CO2, etc. sulfur-containing compounds and inert gases.
From conventional natural gas PNG is very diverse and a large proportion contained therein of heavy hydrocarbons.
The approximate composition of associated petroleum gas derived from oil fields, given below in the table.
|Composition||% of volume*|
|Other heavy hydrocarbons||3,2|
* The table shows one example. Real part of extracted APG from a particular oil field may differ significantly from the given example.
Thus, it appears that APG is extracted from oil fields in the presented example, is a fat (crude) natural gas.
In petroleum and gas fields, the proportion of methane is much larger, and the share of heavy hydrocarbons is correspondingly less.
Production of associated petroleum gas is carried out at any stage of the extraction and processing of oil. This feature is due to the inextricable connection of APG from oil.
First and foremost is extracted associated petroleum gas, which is contained in oil “caps”. He comes out of the hole due to the pressure difference. After that, it extracts gas from the oil by means of separation in special plants – multi-stage separators due to the different pressure and temperature.
Oil extracted from associated petroleum gas is a mixture of various light and heavy hydrocarbons and mechanical impurities (dust and soil). Moreover, the proportion of heavy hydrocarbons is high, and the mechanical and non-hydrocarbon impurities reduce the functional properties of APG.
Intact APG is almost never used (if not to consider its reinjection into the oil reservoir). To use APG for the purpose, it is necessary to remove mechanical impurities, sulfur, carbon dioxide, nitrogen and remove heavy hydrocarbon fraction. This is achieved in various ways: by using cryogenic, membrane, adsorption technology or using technology 3s separation.
The final products of APG processing are natural gas, dry stripped gas, liquefied gas, gas condensate, wide fraction of light hydrocarbons, stable natural gasoline, natural gas, fractions of heavy hydrocarbons.
Accordingly, they can be used in the following way:
as a fuel, including for electricity generation at power plants,
– as a valuable chemical raw material in the chemical, petrochemical and pharmaceutical industries.
Moreover, associated petroleum gas can be used by re-injection into oil-bearing formation with the purpose of intensification of oil recovery. Unfortunately, after extraction of oil injected and this gas must also be recycled because re-injection only postpones the problem of disposal, and rational use of gas.
The optimal variant of the use of associated gas depends on the size of field: small, medium or large, access to transport infrastructure, or the availability of modular mobile plants cleaning, processing and gas liquefaction.
Burning associated gas in flares of oil wells not only causes irreparable harm to the environment, disrupts the ecological situation in the oilfield areas and in the whole world, but also leads to significant economic losses amounting to hundreds of billions of rubles a year.
Firstly, the burning of gas in addition to carbon dioxide produces solid waste in the form of active carbon, the volume of which per year accumulates to 0.5 million tons.
Second, the combustion gas produced excess CO2, which increases the amount of greenhouse gases on the planet Earth.
Thirdly, the methane contained in APG are not fully burned during combustion. In the end, he ends up in the atmosphere and further promotes the growth of the greenhouse effect. In addition to the unburned methane into the atmosphere nitrogen oxide, sulfur dioxide and other heavy unburned hydrocarbons dangerous to humans, plants and animals.
Fourth, around the torch oil wells, the radius of the thermal destruction of soil in the range of 10-25 meters, the vegetation is from 50 to 150 meters.
As a result, this misallocation – utilization of associated petroleum gas leads to significant emissions of solid pollutants to the deterioration of the ecological situation in the oilfield areas and worldwide, the increase in the incidence of the local population: lung cancer, the bronchi, the liver and the gastrointestinal tract, nervous system, vision.
The decree of the Russian Government of 8 January 2009 No. 7 “On measures on stimulating reduction of air pollution products flaring gas in flares” was set a target of gas flaring in the amount of not more than 5 per cent of the extracted associated petroleum gas. According to preliminary estimates of experts, annually in Russia is burned about 25 billion m3 of associated petroleum gas. Although this figure may be significantly understated due to the lack, in many fields of gas metering units.
– gas oil,
– oil shale,
– fuel oil,
– associated petroleum gas,
– natural gas,
– landfill gas,
– shale oil,
– shale gas,
– synthesis gas.
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