Abstract: Comparison of Upper Devonian "Domanik" Source Rock Generative Potential in West Uralian Petroleum Basins, Russia and Kazakhstan

John L. Smale, David A. Wavrek, Jeffrey C. Quick, Steven Schamel, Valentina Pesetskaya, Dmitri Shlygin, Victor Puchkov

Upper Devonian (Frasnian-Famernian) organic-rich black shale and limestone records a major transgressive marine incursion that covered much of the Russian Platform. The Frasnian "Domanik" source rock facies, pervasive in the Pechora, Volga-Ural, and northern Pricaspian basins is shown to be a prolific hydrocarbon source rock. Facies and thickness variations within the Domanik shales in the West Uralian basins are controlled largely by intracratonic grabens (aulacogens) on the Russian Platform. Domanik-type source rocks are found throughout the southern and eastern portions of the Pechora Basin, covering an area of about 200,000 sq km, but are absent in the northern area. Shales attain thicknesses of 100-200 meters in the central portion of the

basin margin due to increased input of detrital limestones eroded from the carbonate platform. Within the Volga-Ural province, the Domanik facies was deposited primarily in the Kamsko-Kinel trough system. Deposition in the Pricaspian Basin was largely controlled by sibsodence in the central Depression. Deeper water Frasnian facies appear to be restricted to isolated troughs and along the flanks of the northern platform.

Geochemical criteria, including assessments of total organic carbon, Rock Eval pyrolysis, gas chromatography, gas chromatography-mass spectrometry, kerogen composition and thermal maturity indicators support the regional importance of the Doinanik facies as oil-prone source rock. Such criteria may be used to distinguish the Domanik facies from the underlying Kynov-Sargay and overlying Farnernian source rocks.

The timing of hydrocarbon generation and migration is predicted by thermal maturation modeling within each petroleum basin. The modeling is supported by kerogen kinetic experiments. Spatial clustering of oil types correlated to the Domanik facies is explained by a complete evaluation of the petroleum system of the West Uralian petroleum basins.

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