Basin-Centered Gas Accumulation in the Timan-Pechora Basin, Russia

B. E. Law, V. Bogatsky, S. Danileksky, L. Galkina, G. F. Ulmishek, and C. W. Spencer

As a consequence of the USAID-funded program between the USGS and ROSCOMNEDRA, a very large basin-centered gas accumulation has been identified in Permian orogenic flysch and molasse rocks in the pre-Ural (Kosyu-Rogov) depression of the Timan-Pechora Basin, Russia. In the Timan-Pechora Basin the Artinskian, Kungurian, and Ufimian (Leonardian- Guadalupian) gas-bearing sequence is as thick as 2,000 m and is composed of interbedded sandstone, siltstone, shale, and coal. Sandstone porosity ranges from 3 to 15% and permeability is commonly less than 0.1 md. Drill-stem and production tests indicate that these rocks are gas saturated with little or no producible water. Pore pressures are abnormally high with gradients of about 0.50 to 0.60 psi/ft The source of the gas is most li ely the interbedded coals and other carbonaceous lithologies. The organic carbon content of these rocks, exclusive of coal, ranges from <0.2 to 4.0 weight percent, averaging 1.5%. The top of the gas accumulation is interpreted to cut across structural and stratigraphic boundaries similar to basin-centered gas accumulations in North America. However, south of the Kosyu-Rogov depression, coal-bearing Kungurian rocks have undergone a facies change into evaporites, forming a regional seal that extends southward into the Volga-Ural Province. The southern extent of the gas accumulation below the evaporite seal is unknown, but it may extend far to the south, making it one of the largest gas accumulations in the world.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California