Exploration History and Future Potential of Paleogene and Mesozoic Rocks in the Substratum of the Pannonian Basin, Hungary
BARDOCZ, B., Hungarian Oil and Gas Corporation, Budapest, Hungary, A. SZALAY, Geophysical Exploration Company, Budapest, Hungary, F. HORVATH, Eotvos University, Budapest, Hungary, and I. KONCZ, Hungarian Hydrocarbon Institute, Nagykanizsa, Hungary
The substratum of the Pannonian basin is made up of Paleogene and Mesozoic deposits and Paleozoic, mostly crystalline rocks. They have been studied for a long time at outcrops in and around the basin, and our knowledge has improved significantly due to recent drilling activity and seismic exploration.
Geochemical data combined with facies interpretations suggest the following possible source rocks of pre-Neogene age: Lower Oligocene "Tard clay," Lower Cretaceous pelagic marls, Upper Liassic (Toarcian) black shales, Lowest Jurassic coal-bearing strata ("Gresten facies"), and Upper Triassic bitumenous shales ("Kossen beds").
The most remarkable success in exploration in Mesozoic rocks has been the finding of the Nagylengyel oil field in 1951 (total production 21 million tons).
Several smaller fields have been found more recently in fractured Mesozoic and Paleozoic reservoirs, although their source rock can be Miocene marls in nearby deep troughs. Simple mass-balance calculations of hydrocarbon gases in the Great Hungarian Plain, however, indicate that known gas reserves are much larger than the potential yield of all available Neogene source rocks. Analyses of gas content of individual pools and isotope geochemistry give evidence that massive gas flux from depth is still going on. Maturity studies also support the view that hydrocarbon generative potential of the Mesozoic and Paleogene substrata of the Pannonian basin is remarkable. We conclude that future exploration can be profitable provided that high technology is combined with adequate experience in po t-orogenic extensional terrains.
AAPG Search and Discovery Article #91007© 1991 AAPG International Conference, London, England, September 29-October 2, 1991 (2009)