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Structures and Hydrocarbon Potential of the Intra-Carpathian Basins of Czechoslovakia

BLIZKOVSKY, M., Geofysika, Brno, Czechoslovakia, V. CIPRYS, Moravian Oil Company, Hodonin, Czechoslovakia, J. FRANCU,* WNP Company, Bratislava, Czechoslovakia, S. HODAN, Nafta Gbely Company, Gbely, Czechoslovakia, I. HRUSECKY,WNP Company, Bratislava, Czechoslovakia, A. KOCAK, Geofysika, Brno, Czechoslovakia, J. MILICKA, Comenius University, Bratislava, Czechoslovakia, M. MORKOVSKY,* Geofysika, Brno, Czechosolvakia, P. MULLER, Geological Survey, Brno, Czechoslovakia, M. PERESZIENYI, WNP Company, Bratislava, Czechoslovakia, and I. HRUSECKY, Nafta Gbely Company, Michalovce, Czechoslovakia

Hydrocarbon prospection and production is concentrated in the Neogene of the Vienna basin, Danube basin, and East-Slovakian (Transcarpathian) basin, in the inner Carpathian Paleogene, and in the Mesozoic of the Vienna basin. Evolution of these basins and their underlying formations have been controlled by different tectonic styles, volcanic activity, and thermal conditions.

Geophysical surveys were comprised of gravimetric, magnetometric, and geoelectric measurements. Seismic methods were applied for mapping the structural units and the fault systems. Internal and detail structures were studied by use of three-dimensional seismic.

Miocene shales and marls contain mostly kerogen types III, II-III, and III-IV. The initial source potential, according to Rock-Eval pyrolysis, is less than 2 kg HC/t of rock, and is quite similar in all three basins with the exception of the upper Karpatian in the East-Slovakian basin, which is barren as a source rock. Source rock maturity was estimated using vitrinite reflectance and pyrolytic and chemical indicators. Hydrocarbon generation was reconstructed from burial and thermal histories in one-dimensional time-temperature models, and contours of the ceiling and floor of the oil and gas windows from maps and regional sections.

Source potential of the Neogene fill was calculated from the initial potential and the degree of kerogen to hydrocarbon conversion. Controlled by geothermal gradient, the total estimated potential decreases from the East-Slovakian to the Danube and Vienna basins; however, prospects of hydrocarbon generation and preservation in the rock increase in the same order, and are best in the Vienna basin.

Most of the reserves are situated in the Neogene sandstones, occasionally in the organogenic limestones sealed by clays, and in the Vienna basin in the underlying Inner-Carpathian Triassic carbonates.

 

AAPG Search and Discovery Article #91007© 1991 AAPG International Conference, London, England, September 29-October 2, 1991 (2009)