HISTORY OF UPPER JURASSIC RESERVOIRS IN SOUTHEASTERN WEST SIBERIA (<i>case study of Igol’sko-Talovoe oilfield</i>)
The Igol’sko-Talovoe oilfield is one of the largest oilfields in southeastern West Siberia, which provides reference for Upper Jurassic reservoirs of the area. The reported studies included integrated interpretation of seismic and well-log data, mapping of tectonic and paleotectonic patterns and sediment thicknesses, as well as seismic-geological and basin modeling. The results were used for tectonic analysis and allowed reconstructing the history of the Igol-Talovoe dome uplift that traps Upper Jurassic oil accumulations. Local uplifts on the Jurassic surface within the Igol-Talovoe dome originated in the Neocomian above basement uplifts produced by erosion and tectonic activity. The local domes merged into a large anticlinal trap as a result of regional-scale vertical crust movements in the Cenozoic. Analysis of the Upper Jurassic hydrocarbon system and basin modeling show that oil generation by the Bazhenov Formaton source rocks began in the Turonian, culminated in the Cenozoic, and continues at present. The process has led to complete filling of the anticlinal trap and formation of the large Igol’sko-Talovoe oilfield. Geological and geophysical data suggest the same scenario for all Upper Jurassic reservoirs in southeastern West Siberia.