Fossil fuels and potential for CO ₂ storage in the Slovenian part of the Pannonian Superbasin

Two Neogene sub-basins of the Miocene Extensional Pannonian Superbasin are located in Slovenia: the Mura-Zala Basin in the NE and the Krško Basin in the east of the country. Their predominantly clastic sedimentary fill hosts diverse geoenergy resources in different geological formations. The basin evolution (e.g. very high Miocene heat flow) was not favourable for the accumulation of large amounts of hydrocarbons. Consequently, oil and gas deposits are limited to the Petišovci–Dolina Field, which was discovered in 1942. The field is located along the Ormož–Selnica–Lovászi Anticline, an inverted Miocene graben structure. Currently, minor amounts of natural gas are produced from Miocene (Badenian and Pannonian) horizons, while oil production stopped in 2021. Coal deposits formed in deltaic environments during the late Pannonian and were exploited until the 1970s, in both the Mura-Zala Basin and the Krško Basin. Depleted oil and gas reservoirs at depths greater than 800 m, saline aquifers and deeply buried coals in the Mura-Zala Basin provide potential sites for CO 2 storage, albeit with limited volumes.