The Petroleum System of the West Part South Caspian Basin

John F. Ruehlman, Michael A. Abrams, Akif Narimanov

The petroleum system of the South Caspian Basin was studied as part of a joint research program between Exxon and the State Oil Company of Azerbaijan. The basin is the site of tremendous Plio-Pleistocene deposition with Quaternary and Middle Pliocene sections reaching thicknesses of 4,000 m and 5,000 m, respectively. Nearly 95% of discovered hydrocarbons are reservoired in Middle Pliocene sandstones. Core porosities exceeding 19% and permeabilities nearly 100 mD were measured from a depth of nearly 6,000 m. The area is highly structured with NW-trending anticlinal zones exceeding 100 Km in length and 3,000 m in vertical relief. Much of the structural amplitude and complexity is associated with Quaternary tectonism, including mud diapirism. Oil analyses suggest one dominan oil family from source rock interpreted as Type II, Tertiary, slightly calcareous clastics. Maturation modeling indicates that the oil window ranges from 6,500 to nearly 12,000 m. Type II thermogenic gas is generated at depths ranging from 12,000 to over 14,000 m. Peak oil generation occurs during the last 2 million years. Vertical migration on the order of 1000's of meters is required to charge the Middle Pliocene reservoirs. Faulting and mud diapirism associated with Quaternary tectonism provides the necessary conduits.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995