ABSTRACT: Major Petroleum Basins of the USSR: Basins on Hercynian Accreted Terranes and Fold Belts

Gregory F. Ulmishek

Major petroleum basins on the Hercynian accreted terranes include the West Siberian, Azov-Kuban, Middle Caspian, and Amu-Darya basins. The South Caspian, East Sakhalin, and North Carpathian basins are connected with fold belts.

The West Siberian basin provides about two-thirds of the oil annually produced in the Soviet Union. The largest oil fields are in the central part of the basin. They produce oil from sandstones of a large Neocomian delta. Structural traps dominate, but an increasing number of stratigraphic pools have been discovered in recent years. The principal source rock is

the Upper Jurassic Bazhenov Shale. The northern part of the basin contains giant gas fields in Cenomanian and Neocomian-Albian reservoirs.

The Azov-Kuban, Middle Caspian, and Amu-Darya basins occupy the northern foredeeps of the Great Caucasus and Kopet-Dag fold systems and adjoining forelands. Gas dominates in the Azov-Kuban and Amu-Darya basins, whereas the Middle Caspian basin is chiefly oil prone. The principal oil production is from Jurassic and Cretaceous carbonate and clastic reservoirs in structural traps. A number of recent discoveries have been made in Triassic rocks restricted to the underlying rift system. Source rocks are in the Triassic, Jurassic, Cretaceous(?), and Tertiary sections.

The South Caspian basin contains a 25-km-thick sequence of Mesozoic and Tertiary rocks. Most productive are middle Pliocene sandstones. Principal oil reserves are concentrated in structural traps of the Apsheron structural sill on the northern basin margin. There, middle Pliocene rocks were deposited in large paleodeltas. Source rocks have not been positively identified and are probably located beneath the deltas.

Small amounts of petroleum are produced in the East Sakhalin and North Carpathian basins from Tertiary clastic rocks.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990