Jurassic and Cretaceous clastic petroleum reservoirs of the West Siberian sedimentary basin: Mineralogy of clays and influence on poro-perm properties

Abstract The West Siberian Sedimentary Basin (WSSB) is the main commercial and the biggest sedimentary basin of Russia and plays a huge role in the Russian oil and gas industry. Three deep wells intersecting full sections of the basin main Jurassic and Cretaceous reservoirs have been studied. This basin consists of two major petroliferous sedimentary sequences: uppermost is of Lower Cretaceous (the Neocomian Sedimentary Sequence) and the oldest petroliferous sandstones of Jurassic age (the Urman-Togur-Tyumen sequence). All the main oilfields of the WSSB are found in sandstone reservoirs, and this paper describes their petrography and mineralogy, emphasizing on the nature and origin of the clay fraction (