Dauletabad-Donmez Gas Field, USSR

CLARKE, JAMES W., U.S. Geological Survey, Reston, VA

The Dauletabad-Donmez field is in southern Turkmenia along the border with Iran. The very large field extends across the greater part of a one-degree quadrangle. The Dauletabad arch was first detected during surveying of Neogene sediments in 1957-1960. Seismic surveying confirmed its presence. The first exploration well was spudded in 1972, and Hauterivian-age (Early Cretaceous) sandstone tested in 1974 yielded a strong flow of gas. The Shatlyk horizon, which is host to the gas pool, dips monoclinally to the north across the area of the field from an evaluation of -2400 m

on the south to -3450 m on the north. East-trending high-angle normal faults divide the field into south, central, and north blocks. Two gas pools compose the field, one in the north block and one in the south block. The reservoirs in the central block are water bearing. The reservoir rock is reddish brown, fine- to medium-grained sandstone. In zones of high-sulfur gas, the sandstone is gray, and pyrite is present. Effective thickness of the reservoir is 18 m on the north block and 10 m on the south. The seal is carbonate rock of Barremian age. The pool is structurally contained on the north and northwest by structural noses. On the east and southeast it is hydrodynamically contained. The deposit must be young, in progress of formation at the present time, because the seals do not app ar effective enough to have held such a large accumulation for a long period of time. Reserves are assessed at 35 trillion ft(3).

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)