Petroleum Systems in the Okhotsk Sea Region

Abstract

Research targets are the largest basins of the Okhotsk Sea region (Northern and Western Sakhalin, Northern Okhotsk and Western Kamchatka). The data on composition, petrophysical and geochemical properties of borehole sections’ rocks, seismic survey (CDP technique) were analyzed. Particular attention was paid to the tectonic and sequence stratigraphic subdivision of covers, identifying sediment structure of petroleum systems and relationships between its components: oil source suits, reservoirs and cap rocks. Three groups of petroleum systems were distinguished: Upper Cretaceous, Lower Cenozoic (Pre-Upper-Oligocene) and Upper Cenozoic (Upper Oligocene-Pliocene). The Upper Cretaceous petroleum systems are the top of the folded (mostly destroyed) basement. The Lower Cenozoic petroleum systems are represented by the rift system with complex sediment structure and random pattern distribution of low permeable reservoirs. The Upper Cenozoic petroleum systems pose the highest petroleum potential. This petroleum systems are characterized by asymmetry associated with unilateral progradation of sequences towards deep-sea trenches. Reservoirs prevail in the proximal and central parts of the sequences; siliceous-argillaceous strata with high oil generation potential are predominated in the distal parts of the sequences.