BIOMARKERS OF EAST SIBERIAN CRUDE OILS

Computerized chromato-mass spectrometry has been used to study higher cyclic biomarkers (steranes, tri-, tetra- and pentacyclic terpanes) of crude oils from the main oil-bearing complexes in East Siberia. On th e basis of the results obtained, the conditions of generation of crude oils have been determined, and the composition of their initial organ ic matter has been established. It was noted that early crude oils of Riphean, Vendian and Lower Cambrian age were generated from marine org anic matter considerably refined by micro-organisms at the sedimentati on stage. Crude oils of Upper Permian, Lower Triassic and Lower Jurass ic deposits from the Vilyuisk syneclise were generated from typical co ntinental organic matter. All the crude oils studied are catagenetical ly mature.