Geochemical background of Berezovsky depression oil and gas potential (eastern Siberia)

Abstract

Berezovsky depression, located on the northeast of the Pre-Patom foredeep, is a promising target for hydrocarbon prospecting, as evidenced by oil and gas shows established while drilling, the presence of structures and natural reservoirs. However, this area has not yet been adequately explored due to the low drilling density. Geochemical study of organic matter (OM) of the Riphean, Vendian and Lower Cambrian sediments showed that the main oil and gas source rock is represented by terrigenous-carbonate Vendian deposits. Rocks of the Seralakh Formation possess highest initial and residual potential, as well as interlayers of rocks with heightened content of algal OM in the Vendian and Lower Cambrian sections. The oxidation of OM during sedimentation and the presence of bottom algae could have a negative impact on the generation potential of these deposits, which led to a decrease in OM concentrations and deterioration of kerogen; most likely, these factors determine the smaller resources of the Berezovsky depression. Probably, the study of the Riphean complex deserves attention, because there are oil-source rocks highly enriched in OM in the Middle and Upper Riphean of the south-west of the Baikal-Patom fold zone, the transformation of which is corresponded to peak of «oil window» – «gas window».

Keywords

• berezovsky depression
• oil source rocks
• generation potential of organic matter
• hydrocarbons