Timan-Pechora Basin and Basins of the Barents Sea Shelf

Gregory Ulmishek

More than 50 oil and gas fields with recoverable reserves of about 3.4 billion bbl of oil and 20 tcf of gas have been discovered in the Timan-Pechora basin. The major part of reserves is concentrated in clastics of Middle Devonian age and in the upper part of the Carboniferous-Lower Permian carbonate sequence. The Ordovician-Lower Devonian, Upper Devonian-Lower Carboniferous, and Upper Permian-Triassic sequences are much less productive. Upper Devonian bituminous shales and carbonates (Domanik facies) that were deposited in a large intrashelf depression constitute the major source rock formation. Many fields, including the giant Usa oil field, are controlled by a system of northwest-trending inverted-graben rifts. Hercynian Ural foredeeps superimposed during the Permian-T iassic on older northwestern structures are gas prone. The Timan-Pechora basin geology is traced some distance offshore, but the prospective Paleozoic sequence progressively dips northward under thick Upper Permian-Mesozoic clastics.

The petroleum potential of the poorly explored Barents Sea is chiefly connected with a system of deep depressions (Finnmark Trough, South Barents, and North Novaya Zemlya depressions) that surround from the south and east the generally uplifted northwestern and northern regions of the shelf. Triassic-Jurassic clastics are the main target for exploration although upper Paleozoic carbonates may also be productive. The petroleum potential of the depressions and expected ratio between oil and gas essentially depend on the distribution and facies of Lower to Middle Triassic source rocks. Upper Jurassic bituminous shales may be mature only locally. The most probable amounts of undiscovered petroleum resources of the shelf are estimated at 14.2 billion BOE and 312.2 tcf of gas.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.