PICHA, FRANK J., Chevron Overseas Petroleum Inc., San Ramon, CA; and KENNETH E. PETERS, Mobil Technology Company, Dallas,TX

Abstract: Biomarker Oil-to-Source Rock Correlation and Petroleum System Definition in the Western Carpathians and Their Foreland, Czech Republic

Four oil samples from reservoirs in the sub-Carpathian foreland plate and one sample from the Vienna Basin in Moravia (Czech Republic) were analyzed and geochemically compared to extracts from prospective Jurassic and Paleogene source rocks. Two oils from the Lubna-18 and Dolni Lomna-1 wells, from the subthrust foreland plate in Northern Moravia, are related and contain abundant oleanane, which indicates a source rock not older than Late Cretaceous. These two oils show high 24-nordiacholestane ratios, consistent with a Tertiary source rock. Most likely, these oils originated from Paleogene organic-rich rocks, either the Menilitic shales of the Carpathian flysch belt or, more likely, from the autochthonous Paleogene deposits buried below the flysch belt.The other two oils, from the Zdanice-7 and Damborice-16 wells in the subthrust foreland plate of Southern Moravia, lack oleanane and show low 24-nordiacholestane ratios, and are most likely derived from Jurassic organic-rich marls.The Tynec-34 oil from a Neogene reservoir in the Vienna basin appears to be a mixture of the two oil groups.

Biomarker analyses thus indicate that at least two petroleum systems operate in the Vienna basin, Carpathian thrust belt, and the European foreland plate in Moravia, one associated with the Jurassic source rocks and the other related to the Paleogene organic-rich rocks. In addition to the Menilitic shales of the Carpathian thrust belt, the Paleogene system also includes autochthonous marginal deposits in the subthrust plate, which may be present below the entire Carpathian belt and thus enhance its prospectivity.

AAPG Search and Discovery Article #90923@1999 International Conference and Exhibition, Birmingham, England