The Influence of Tectonic Activity on Drainage Networks and Hydrocarbon Prospectivity in Siberia

O’Reilly, Cian, Tom Wilson, Jeffrey Standring, Fugro-Robertson, Llandudno, United Kingdom

Jurassic rifting in the Yenisey-Khatanga basin in East Siberia was followed by Berriasian inversion and fine-grained clastic sedimentation. This persisted until the Valanginian, when development of the Laptev Sea and Verkhoyansk fold belts (initiated by terrane collisions on the northern and northeastern margins of East Siberia) resulted in diversion of the continen­tal drainage networks of East Siberia northwest towards the Yenisey-Khatanga Basin. The sudden influx of greatly increased sand volumes resulted in rapid deposition of laterally extensive clinoforms throughout the Yenisey-Khatanga basin and on into the West Siberia Basin, where they prograded over the organic-rich Bazhenov Formation. Individual clino­forms extend for hundreds of kilometers parallel with the palaeo-shoreline along the eastern margin of West Siberia. They may be tens of kilometers wide, up to 300m maximum thick­ness and dip shallowly to the west (Clark, 1999; Ulmishek, 2003). Extensional collapse of the Laptev Sea fold belt, from the Barremian onwards, resulted in another diversion of the drainage pattern to the north and terminated clinoform deposition.

The Neocomian clinoform complex is the largest play in the West Siberia Basin, account­ing for more than 90% of total oil production, with large and giant fields in stratigraphic and structural traps (Pinous et al. 1999). The Mesozoic tectonic development of Siberia, and the evolution of the drainage network responsible for deposition of these important hydrocar­bon reservoirs, will be presented. Understanding of these factors guides our prediction of reservoir distribution in the greater Siberia region.