The South Caspian Basin encompasses the southern extension of the Caspian Sea, including land areas in eastern Azerbaijan, western Turkmenistan, and northern Iran. The region is endowed with abundant petroleum resources, and oil and gas production has played an important commercial role in the region for more than 150 years, especially in Azerbaijan and to a lesser extent in Turkmenistan. Major oil reserves are concentrated in 2,500–3,500 meters of shallow-marine, deltaic to lacustrine deposits of middle Pliocene age. The richest source rocks are in the middle part of the Oligocene–Miocene Maykop Series. The principal reserves and targets for future exploration are in the middle Pliocene Productive Series. In this depositional environment, good reservoir porosities and permeabilities could be preserved to depths as great as 12 kilometers. The Oligocene–Miocene Maykop/Diatom Total Petroleum System within the South Caspian Basin is separated into five hydrocarbon assessment units: Apsheron-Pribalkhan Zone, Lower Kura Depression and Adjacent Shelf, Gograndag-Okarem Zone, Central Offshore, and Iran Onshore-Nearshore.

¹Geoscience Department, University of Texas at Dallas, F.O. 21, Box 830688, Richardson, Texas 75083-0688.