Tectonic Setting and Hydrocarbon Habitat of External Carpathian Basins in Romania

Abstract

During the Alpine evolution of Romania, two distinct depositional areas evolved in the external zones of the Carpathians: the Paleogene flysch and Neogene Molasse basin of the eastern Carpathians, and the Paleogene and Neogene Molasse basin of the southern Carpathians. Both basins were compressionally deformed during the Neogene, giving rise to the development of a succession of nappes and thrust sheets. The internal elements of the external Carpathians corresponding to the Tarcau and marginal folds nappes and the external elements forming the sub-carpathian nappe and foredeep were thrusted over significant distances onto the European platform. Intense exploration of the external Carpathian thrustbelt has led to the discovery of more than 100 oil and gas pools. Reservoirs are provided by Oligocene, Burdigalian, Sarmatian, and Pliocene clastic rocks. A prolific hydrocarbon charge is derived from regionally distributed Oligocene oil source rocks. Traps are mainly of the structural type and involve faulted anticlines, [open quotes]scale folds,[close quotes] and compressional structures modified by salt; stratigraphic pinch-out and unconformity related traps play a secondary role. On the basis of selected examples, the development and distribution of hydrocarbon pools will be discussed in terms of thrust kinematics and the structure of different platform blocks. The philosophymore » of past exploration activities will be reviewed, and both success cases and failures will be discussed. Remaining oil and gas plays, aimed at shallow as well as at deep objectives, will be highlighted.« less