LAFARGUE, ERIC, N. ELLOUZ, and F. ROURE, Institut Francais du Petrole, Rueil-Malmaison, France

ABSTRACT: Thrust Controlled Exploration Plays in the Outer Carpathians and their Foreland (Poland, Ukraine And Romania)

A comprehensive geological and geochemical survey conducted over different sections of the Outer Carpathians and their foreland in Poland, Ukraine and Romania illustrates the influence of thrusting on the location of oil and gas accumulations in this area. In particular, migration pathways for hydrocarbons and distances of migration are directly controlled by the location and the timing of thrusting.

Thrusting of Cretaceous to Paleogene flysch masses over the European and Moldavian foreland platforms is a Neogene multiphase process with the most intensive phase of overthrusting taking place during the Miocene. In the innerpart of the Neogene foreland basin, the Oligocene Menilite Shale, recognized as the main source-rock, became sufficiently deeply buried with continuing sedimentation to start generate oil. This oil migrated over a long distance towards the reservoirs of the lithospheric bulge, forming the present day foreland oil fields. This implies that traps suitable for hydrocarbon accumulation existed already in the Neogene. With continuing overthrusting, part of the immature Menilite shale became deeply buried in response to tectonic overbudden and oil was generated. Due to the complex structural setting, migration was no longer to the lithospheric bulge, but towards reservoirs within the overthrust itself and over shorter distances.

The combination of seismic interpretation, cross-sections balancing, analysis of outcrops with detailed geochemical analyses of crude oils and source-rocks extracts has made possible the reconstruction of the petroleum scenario described herein for the whole Carpathians. This combination of geological and geochemical techniques gready helped for the understanding ofthe present oil accumulations as well as for the recognition of possible plays for future exploration.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.