Biodegradation of heavy crude oils from Labaganskoye and Inzyreyskoye oilfields.

The process of biodegradation of oils of the Arctic zone of Russia—Labaganskoye and Inzyreyskoye oilfields (Timan-Pechora Oil and Gas Basin) was investigated. The native hydrocarbon–oxidizing microflora of reservoirs had a small hydrocarbon–oxidizing activity, which was increasing after blending with additional source of mineral nutrition— an acid composition of prolonged action developed at the Institute of Petroleum Chemistry. During biodegradation, the structural composition of oils was changing—saturation index decreased, aromaticity and oxidation indexes increased. In the group composition of oils, the relative content of n-alkanes and naphthenoarenes increased, and the content of cyclic and aromatic hydrocarbons decreased. These changes were clearly defined in the presence of an acid composition, which indicates the possibility of a complex effect from the use of the composition and native reservoir microflora in enhanced oil recovery (EOR) techniques. [ABSTRACT FROM AUTHOR]