West Siberian basin
The West Siberian petroleum basin (variously known as the West Siberian hydrocarbon province, Western Siberian oil basin, etc.) is the largest hydrocarbon (petroleum and natural gas) basin in the world covering an area of about 2.2 million km2.
Geographically it corresponds to the West Siberian plain. From continental West Siberia, it extends into the Kara Sea as the East-Prinovozemelsky field.
The public domain U.S. Geological Survey Bulletin 2201-G describes the basin as follows.
The basin occupies a swampy plain between the Ural Mountains and the Yenisey River. On the north, the basin extends offshore into the southern Kara Sea. On the west, north, and east, the basin is surrounded by the Ural, Yenisey Ridge, and Turukhan- Igarka foldbelts that experienced major deformations during the Hercynian tectonic event and the Novaya Zemlya foldbelt that was deformed in early Cimmerian (Triassic) time. On the south, the folded Caledonian structures of the Central Kazakhstan and Altay-Sayan regions dip northward beneath the basin’s sedimentary cover. The basin is a relatively undeformed Mesozoic sag that overlies the Hercynian accreted terrane and the Early Triassic rift system. The basement is composed of foldbelts that were deformed in Late Carboniferous–Permian time during collision of the Siberian and Kazakhstan continents with the Russian craton. The basement also includes several microcontinental blocks with a relatively undeformed Paleozoic sedimentary sequence.
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