Abstract: Basin-Centered Gas Accumulation, Dneiper-Donetsk Basin and Donbas Region, Ukraine

LAW, B.E., B.P. KABYSHEV, A.Yu. POLUTRANKO, G.F. ULMISHEK, and T.M. PRIGARINA

A large basin-centered gas accumulation has been identified in the Dneiper- Donetsk Basin and Donbas region of Ukraine. The identification of the gas accumulation was facilitated by the utilization of analogs from North America and the interpretation of drilling reports, pressure, temperature, fluid recovery, and thermal maturity data. The gas accumulation occurs in low-permeability, Carboniferous age sandstones at depths ranging from a few hundred meters in the Donbas region to about 4.5 kilometers in the central part of the Dneiper-Donetsk Basin. Indirect evidence indicates that abnormally high pressures are coincident with the gas accumulation in the deeper parts of the Dneiper-Donetsk Basin, whereas abnormally low pressures are coincident with the gas accumulation in the Donbas region. The top of the gas accumulation in the Dneiper-Donetsk Basin is nearly coincident with the 0.9% R_o isoreflectance line and the 100 degreesC isotherm line. However, in the structurally inverted Donbas region adjacent to the Dneiper-Donetsk Basin, the strata are in a state of extreme thermal disequilibrium; present-day temperatures and vitrinite reflectance cannot be used to estimate the depth to the top of the gas accumulation. The thickness of the gas accumulation is uncertain but it is at least 1,000 m through most of the basin. The source of the gas is inferred to be the interbedded coal beds and other carbonaceous lithologies. In order to exploit this large basin-centered gas accumulation, we suggest that future exploration efforts focus on identifying structural and stratigraphic "sweet spots" within the upper part of the accumulation.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria