IX Международная студенческая научная конференция Студенческий научный форум - 2017

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.

Molecular composition

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.

The gas can be utilized in a number of ways after processing: be sold and included in the natural gas distribution networks, used for on-site electricity generation with enginesor turbines, reinjected for enhanced oil recovery, be converted from gas to liquids producing synthetic fuels or used as feedstock for the petrochemical industry. Russia is the world leader in the flaring of APG, and flares 30 per cent of the total APG flared globally.

The largest volumes of APG historically have been produced in Western Siberia, which accounts for the majority of past and current oil production in Russia. However, APG production has increased in other regions due to oil field developments, particularly in Eastern Siberia.

The majority of the APG produced in Western Siberia originates from oil fields in the Khanty-Mansisk. Autonomous Okrug, which contains more than 220 active fields and produces about 57% of Russian oil.

Most flaring in Western Siberia is located within an area of less than 500 x 500 km. This area contains significant infrastructure for gas processing and transportation and is located less than 300 km from the main transmission pipelines serving the Western part of Russia and export markets.

Ecologists’ fears

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’s why the problem of its disposal was settled in rather an easy way – 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.

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’t happen, oil companies will be liable to stiff fines.

Options of use

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. 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’s 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 – 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.

The barriers to flare reduction are well known and recognized. Some barriers have been reduced, among others through political action, while others now are more important with a large share of flare sites being small and medium size often situated in remote locations.

Barriers can be grouped in three broad categories:

1. Technical and geographical barriers. This refers primarily to the location of flare sites and low volume of APG production per field. In particular, scattered and small flare sites in remote locations away from gas infrastructure represent a serious hindrance to APG investments.

2. Structural barriers. Production/flare sites are typically owned and operated by a variety of companies while gas infrastructure, including processing facilities and transport lines, are owned and/or controlled by large entities, often monopolies. In many cases APG investments have been stalled due to lack of commercial agreement on terms for access of stranded gas into the infrastructure. This problem has been given considerable political attention recently with reforms being passed both in Russia and Kazakhstan. However, it remains to be seen to what extent and how quickly processing and transportation access for APG producers will be improved.

3. Economic barriers. This refers to economies-of-scale and external economic parameters such as gas and power prices, as well as taxes and other public schemes, which may impact on the financial viability of APG investments. A common problem is that power and gas prices are kept low for political reasons and hence reduces the “true economic value” of APG utilization investment. This problem continues to be an important barrier in all target countries of this Study. On the other hand it can be added that in the absence of good monitoring, companies may be ignorant of the economic potential from productive use of the APG.

In the past, associated gas was considered a waste product, or by-product, of crude oil production with little economic value. Among industry executives the attitude has changed, due to higher value for the gas, regulatory and political pressures and company-internal standards. Still, APG investments must on compete with other projects for financial, human and managerial resources, and beating oil production expansion investments is often difficult. Generally it is easier to have funds allocated for APG utilization investments when they are part of new field developments than flare elimination investments from existing producing fields, particularly if such fields are in decline and have limited remaining economic lifetime. Regulations therefore play a particularly important role in relation to flare elimination from existing fields where the economic return on investment may be uncertain or negative.

References:

1. https://en.wikipedia.org/wiki/Associated_petroleum_gas

2. http://www.gazprominfo.com/articles/associated-gas/

3. T. Haugland, Associated Petroleum Gas Flaring Study for Russia, Kazakhstan, Turkmenistan, and Azerbaijan, Carbon Limits, Oslo, 2013.

4. Business Magazine "Neftegaz.RU" № 5, Neftegas.ru, Moscow, 2013

5. http://fb.ru/article/177498/poputnyiy-neftyanoy-gaz-sostav-prirodnyiy-i-poputnyiy-neftyanoy-gaz

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