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The West Siberian petroleum basin (also known as the West Siberian hydrocarbon province or Western Siberian oil basin) is the largest hydrocarbon (petroleum and natural gas) basin in the world covering an area of about 2.2 million kmĀ², and is also the largest oil and gas producing region in Russia. Geographically it corresponds to the West Siberian plain. From continental West Siberia, it extends into the Kara Sea as the East-Prinovozemelsky field. Beneath lie remnants of the Siberian traps, thought responsible for the Great Dying 250 million years ago.