Milička J., Kopal L., Kudlička L. & Polc R., 2015: Hydrocarbons in the Slovak part of the Danube Basin. Acta Geologica Slovaca, 7, 2, 175–186.

Hydrocarbons in the Slovak part of the Danube Basin

Uhľovodíky v slovenskej časti Podunajskej panvy

Ján Milička, Lukáš Kopal, Lukáš Kudlička & Róbert Polc

Department of Geochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava; milicka@fns.uniba.sk

Abstract

The Danube Basin is one of our largest Neogene basins in Slovakia with the highest volume of potential source rocks in active hydrocarbon generation zones. The source rocks, however, are quite poor with low hydrocarbon potential. In Blatné- and Rišňovce depressions at the northern part of the Danube Basin only early oil and oil generation window were reached below 2900 m during the Upper Miocene to Pliocene, due the lower temperature. In the southern Central Gabčíkovo Depression (CGD) that is explored by drilling only to 2700 m, all generation zones up to dry gas zone have been reached according to modeling. While the oil generation zone was reached at approximately 2800 m, dry gas is expected below 4000 m. The natural gas molecular composition and methane carbon isotopes indicate small local natural hydrocarbon gas accumulations associated mostly with oil generation that migrated to present reservoirs and mixed with biogenic methane. The carbon dioxide and partly also nitrogen here are most likely related to volcanic activity. The gasoline hydrocarbon range indicates that non biodegraded gasoline oil from the FGČ1 Čilistov well in the CGD is thermally very mature, with its origin most likely in the deeper parts of the CGD below 3500 m. In contrast, the oil trace from Sereď5 (Se5) well is strongly biodegraded and according to the sterane correlations it could have originated in any examined Neogene source reaching the oil window.

Key words: natural gas, gasoline oil, oil traces, Danube Basin, Slovakia

Manuscript received: 2015-03-19

Revised version accepted: 2015-10-07