Abstract: Prediction of Source-Rock Organic Facies Variations Using Advanced Geochemistry: Northeastern Sakhalin Island, Russia

PETERS, K.E., M. WOODS, G. SPENCER, C.C. WALTERS, R.J. MOIOLA, J.B. WAGNER, R.J. ECHOLS, AND J.E. WELTON

Advanced biomarker, isotopic, and chemometric analysis of crude oils and potential source rocks show that two organic facies of the same Lower Miocene to Upper Oligocene marine siliciclastic source rock generated most of the oils in northeastern Sakhalin Island. A distal deltaic facies generated most offshore oils and is more oil-prone than the proximal deltaic facies which generated most onshore oils. The oils were not derived from an anoxic, deep marine siliceous source rock like the Miocene Monterey Formation in California. Calibrations of biomarker data for source-rock samples were used to predict the regional generative potential of the source rock (initial hydrogen index) and initial gas-to-oil ratios (GOR) of the thermally generated products. Kinetic results suggest that expulsion from the source rocks occurred prior to the peak of the oil window. Integration of geochemical, sedimentologic, and structural history data shows that the timing of petroleum system events in the study area was favorable for the accumulation and preservation of significant amounts of hydrocarbons. The conclusions of this study differ substantially from the literature and reiterate the key role played by cutting-edge technology in assessing exploration risk.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria