New Interpretations of the Evolution of the West Siberian Basin, Russia: Implications for Exploration and Production

John Dolson¹, V. Igoshkin², D. Sidarov², O. Bakuev¹, S. Hafizov¹, and R. Herbert¹

¹Exploration, TNK-BP, Moscow, Russian Federation
²Exploration, Geoseis Company, Tyumen, Russian Federation

Russia’s West Siberian basin is the largest petroleum basin in the world. With proven reserves of 450+ BBOE it will remain a strategic energy resource for the next millennium. New regional maps shed new light on the basin’s evolution and petroleum system.

Late Paleozoic collision of the East Siberian plate with the European craton resulted in development of the Ural Mountains on the western margin. East of the Urals, assemblage of large blocks of accreted Paleozoic terrains created topographic relief locally exceeding 2 kilometers. Early Triassic sub-basins formed during post collision sag. These terrains and Triassic basins not only fundamentally controlled patterns of Jurassic deposition, but exerted a profound influence on geothermal gradients and source rock maturation.

Early Jurassic transgressions deposited source rock and reservoirs in large estuaries. Episodic fill ended when the upper Jurassic Bazhenov source rock finally buried most of the terrains. Neocomian regressions deposited multiple shoreline, deltaic and deep water sandstones over the Bazhenov, forming the most important reservoirs.

Major strike-slip faults split the basin into several tectonic elements and control the location of many of the most prolific hydrocarbon accumulations. Regional mid-Tertiary uplift removed up to 2.5 kilometers of sediment, resulting in expansion of gas caps and flushing of earlier oil accumulations, particularly in the Yamal autonomous region. Oil rims around the edges of gas accumulations are common, as are residual saturations in numerous resevoirs.

While most large structures have been drilled, deeper overpressured horizons and stratigraphic traps will provide abundant new hydrocarbon resources well into this next century.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas