2nd International Conference “Alpine-Petrol'2012” HISTORY OF OIL AND GAS PRODUCTION IN THE CROATIAN PART OF THE PANNONIAN BASIN SYSTEM Josipa VELIĆ1, Tomislav MALVIĆ1,2 and Marko CVETKOVIĆ1 1Department of Geology and Geological Engineering, University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering, Pierottijeva 6, 10000 Zagreb, Croatia;
[email protected] 2Sector for Geology and Reservoir Management, INAIndustry of Oil Plc., Exploration and Production of Oil and Gas, Šubićeva 29, 10000 Zagreb, Croatia Introduction On the basis of historical data, Croatia belongs to the first few pioneer countries in the world in which oil accumulations were researched and produced in the middle of the 19th century. Earlier oil production was only recorded in Russia, France, Romania and Germany. Application of oil in industrial purposes has a long tradition in Croatia, e.g. applications in medicinal preparations were recorded as early as in 14th and 15th century as “asphalt and petroleum”. More intense exploitation began just before the 2nd World war. Geological outline The Pannonian Basin System (PBS) is a back arc basin system that belongs to an area in the past covered by the Central Paratethys, and younger brackish and fresh-water environments formed from Paratethys. Inside PBS, numerous basins, depressions and subdepressions were formed along dextral and sinistral strike-slip faults. The area of the PBS in Croatian part is divided into the Drava, Sava, Mura, and Slavonija-Srijem depresions (Fig. 1A). The general evolution of their depositional environments, transport mechanisms, tectonics and dominant lithologies is very similar. Basin infill is manly comprised of Neogene-Quaternary rocks: breccia, conglomerates, sandstones, marls, shales, biogene limestones and efusives (1st megacycle – Lower and Middle Miocene), sandstones and marls (2nd megacycle – Upper Miocene) and clays, sands, loess and gravel (3rd megacycle – Pliocene, Pleistocene and Holocene) (Velić et al., 2002).