Abstract: Redevelopment of Pliocene Reservoirs, Eastern South Caspian Basin of Western Turkmenistan

David R. Nelson, Robert B. O'Connor Jr.

Since the early part of the 20th century, the Pliocene reservoirs of the South Caspian basin in the Republic of Turkmenistan have been known to contain reserves of "world class" proportion. However, due to internal constraints in the former Soviet Union, the producing fields have not received the development attention they deserve. Maximum oil production of 312,000 barrels of oil per day from fields in Western Turkmenistan was reached in 1973. Since this time, production has decreased 71% to 90,000 barrels of oil per day in 1992.

The Pliocene reservoirs are typified by moderate levels of porosity (16-25%) and permeability (100-200 md), high reservoir pressures, extreme heterogeneity, paraffinic oils and low resistivities that make log analysis very difficult using traditional methods. Difficulties in constructing accurate geologic reservoir models have hampered development efforts and delayed or stopped delineation of discovered fields.

A case study of the Gogran-Dag field has shown that through the re-evaluation of reservoir volumetric parameters and the application of modern completion techniques and production equipment, recoverable reserves can be increased by over 600% to 110 million barrels. The use of a new geologic model could expand future recoverable reserves to 438 million barrels of oil and 7 trillion cubic feet of gas.

The structure of joint ventures offered by the government of Turkmenistan allow a foreign company to "self-fund" the development, delineation and exploration projects out of incremental production increases realized from relatively simple workover and maintenance procedures. This minimizes the risk to the foreign company while providing access to significant future reserve additions.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994