Comparative Analysis of Thermal History and Perspective of Oil-gas Generation in Sedimentary Sections of the South Barents Depression and the Admiralteyskoe Rise

Yurii Galushkin

An oil prospecting is an actual task in the East Barents region despite the fact that several great gas and gas-condensate deposits were discovered in the region. For assessment of oil-gas perspective of the region we compared the thermal and HC generation histories of the Paleozoic, Mesozoic and Cenozoic sedimentary rocks in the South Barents depression with similar characteristics of the Admiralteyskoe rise. Our analysis is based on numerical modeling in the frame of the GALO basin modeling system, which was carried out for Krestovaya, Admiralteyskaya and Pachtusova areas in the Admiralteyskoe rise, for Ludlovskaya, Ledovaya, Shtokmanovskaya, Arkticheskaya areas in the South Barents depression and for Peschanoozernaya, Pomorskaya and Severo-Gulyaevskaya areas in the southern Barents sea. An basin evolution of the lithosphere in the South Barents depression includes the continental rifting in the Devonian and considerable thinning of the crust in the Permian and Triassic, associated with intensive sedimentation. Radio-active heat of thick sedimentary cover contributes sufficiently in recent heat flow of the region. The modeling suggests more intensive thermal activation of the lithosphere in the northern areas that in the southern ones. It corresponds to increase in present-day heat flow toward the North. Numerical analysis assumes that the liquid hydrocarbons generated by the Ordovician, Silurian and Devonian deposits in the the Admiralteyskaya and Pachtusova areas and by Devonian, Permian and considerable part of Triasssic rocks in the South Barents depression were subjected (perhaps, partly) to secondary creaking. The Carboniferous, Permian and Lower Triassic rocks at the depths of 1000 - 3.600 m in the present-day section of Admiralteyskaya and Pachtusova areas are predominantly oil-generating, whereas deeper horizons can be considered as gas prone. In the recent sections of the Ledovaya, Shtokmanovskaya and Arkticheskaya areas the rocks at the depths of 2500 - 4.200 m are oil prone. Thus, sufficient part of the Permian-Triassic deposits in center of the South Barents depression occurs within the zone of gas generation. Migration of gas hydrocarbons toward the East can be reason of movement of oil accumulations to the same direction. Formation of secondary oil and gas deposits can be caused also due to step-rising migration of hydrocarbons along the tectonic dislocations in the eastern slope of the Admiralteyskoe rise.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013