What Is Associated Petroleum Gas?
Associated petroleum gas (APG)¬†is¬†gas dissolved in¬†oil. Associated petroleum gas is¬†produced in¬†the process of¬†oil production, so¬†it¬†is¬†actually a¬†derivative. But APG itself is¬†also a¬†valuable raw material for further processing.
Associated petroleum gas is¬†composed of¬†light hydrocarbons. First of¬†all, from methane, which is¬†a¬†major component of¬†natural gas, and from other heavier components, such as¬†ethane, propane, butane and others.
All these components differ in¬†the number of¬†carbon atoms in¬†a¬†molecule. Thus, there is¬†one carbon atom in¬†a¬†methane molecule, two in¬†ethane, three in¬†propane, four in¬†butane, etc.
Some¬†400,000¬†tons is¬†a¬†weight of¬†6¬†super heavy lift launch vehicles.
According to¬†the World Wildlife Fund (WWF) data, in¬†oil producing regions the annual volume of¬†solid pollutants emitted into the atmosphere (APG combustion products accounting for their considerable part) reaches¬†400,000 tons.
Associated petroleum gas should be¬†separated from oil for the oil to¬†comply with the applicable standards. For a¬†long time, APG used to¬†be¬†a¬†by-product for oil companies, that‚Äôs why the problem of¬†its disposal was settled in¬†rather an¬†easy way¬†‚Äď¬†it¬†was burnt.
Not too long ago when flying over Western Siberia one could observe a¬†multitude of¬†burning flares: that was associated petroleum gas being burnt.
In Russia the annual emission volume of¬†CO2 caused by¬†gas combustion in¬†flares totals some 100 million tons.
Another threat lies in¬†black emissions: ecologists think that black microparticles may travel long distances and settle on¬†snow or¬†ice surface.
Even the slightest pollution of¬†snow and¬†ice unseen for the eye, considerably decreases their albedo, that is¬†their reflectivity. As¬†a¬†result, snow and surface air heat up, and our planet reflects smaller amounts of¬†solar radiation.
Reflectivity of¬†unpolluted snow:
Changes for better
Recently, the situation with APG disposal has started to¬†change. Oil companies pay more and more attention to¬†the issue of¬†associated gas rational use. This process is¬†accelerated by¬†the Russian Federation Government Resolution No.7¬†of January 8, 2009, which stipulates the requirement that the associated gas use level should reach 95¬†per cent. If¬†this doesn‚Äôt happen, oil companies will be¬†liable to¬†stiff fines.
Gazprom elaborated the Medium-Term Investment Program for Enhancement of¬†APG Use Efficiency over 2011¬†to 2013. In¬†2010¬†the APG use level within Gazprom Group amounted to¬†the average of¬†64¬†per cent, moreover, Gazprom Dobycha Orenburg, Gazprom Pererabotkaand Gazprom Neft Orenburg already use 100¬†per cent of¬†APG.
There are many ways of¬†APG rational use, but only few are applied in¬†practice.
The basic way of¬†APG use is¬†its separation into components, mostly represented by¬†stripped dry gas (actually, natural gas, methane for the most part, which may contain some ethane). The second group of¬†components is¬†represented by¬†natural gas liquids (NGL). It¬†is¬†a¬†substance mixture with two or¬†more carbon atoms (C2+¬†fraction). It¬†is¬†this mixture which is¬†used as¬†a¬†raw material in¬†petrochemistry.
Associated petroleum gas separation processes run at¬†low-temperature condensing and low-temperature absorption units. After the separation, stripped dry gas may be¬†conveyed through a¬†conventional pipeline, whereas NGL may be¬†delivered for further processing to¬†produce petrochemicals.
According to¬†the data provided by¬†the Ministry of¬†Natural Resources and Environment, in¬†2010 largest oil companies used 74.5¬†per cent and flared 23.4¬†per cent of¬†the total amount of¬†gas produced.
The plants for gas, oil and gas condensate processing into petrochemicals are high-technology complexes combining chemical and petrochemical facilities. Hydrocarbon feedstock is¬†processed at¬†facilities of¬†Gazprom‚Äôs subsidiaries, that is¬†at¬†the Astrakhan, Orenburg and Sosnogorsk Gas Processing Plants, the Orenburg Helium Plant, the Surgut Condensate Stabilization Plant and the Urengoy Condensate Treatment Plant.
Associated petroleum gas may also be¬†used at¬†power generation units for¬†‚Äď¬†this allows oil companies to¬†settle the issue of¬†power supply to¬†infrastructure facilities without electricity purchases.
Moreover, APG may be¬†reinjected into a¬†formation to¬†increase the oil recovery factor. This process is¬†called cycling.