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Petroleum Geology of Caspian Region of USSR

Gregory Ulmishek

The Caspian Sea transects three separate and distinct tectonic basins: north, middle, and south. In the North Caspian basin, large gas and condensate pools are associated with Carboniferous and Lower Permian anticlines and reef structures along the margins. A Permian salt seal is present through most of this province. Triassic to Cretaceous sediments are oil producers on the southeast.

The Middle Caspian basin is located at the junction of the Sythian and Turanian platforms. In its southwest part is the foredeep of the Greater Caucasus fold system, which is filled by upper Paleogene-Neogene molasse deposits. The main pays are Jurassic and Cretaceous in age. Tertiary sediments are productive in the foredeep.

The South Caspian basin is an intermontane downwarp between the Greater Caucasus on the north and the Lesser Caucasus and Kopet-Dag on the south. It extends across the southern Caspian Sea and includes large areas on both sides. The main pay is the Pliocene productive unit on the west (Baku region) and the red-bed unit on the east in Turkmenia. Major oil reserves are concentrated in deltaic deposits of the middle Pliocene Volga and Amu-Dar'ya Rivers. Exploration is now active offshore in the Caspian Sea.

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