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.