Several petroleum provinces in southeastern Hungary are part of the greater late Miocene-Pliocene Pannonian basin of central Europe. The Pannonian basin formed as a tensional basin in early-middle Miocene time (17-12 Ma) when thick (<1250 m) marine bioclastic carbonates were deposited. Pre-Miocene basement rocks are composed of lithologically and structurally complex rocks of Precambrian to Mesozoic age. Overlying the basement rocks and the marine carbonates are thick (<4500 m) lacustrine Pannonian rocks of late Miocene and Pliocene age. Gas production with some oil and condensate is predominantly from structural and combination traps. Part of one petroleum system present in southeastern Hungary consists of middle-upper Miocene source rocks and reservoir rocks. Frac ured Precambrian rocks are the next most important reservoir rocks. Gas and oil generation began less than 6 Ma and is continuing today.

Overpressuring is regionally present in rocks at drill depths greater than 2500 m. The overpressuring is caused by a combination of undercompaction (incomplete sediment dewatering) and active hydrocarbon generation from middle-upper Miocene source rocks. Some overpressuring may be caused by thermally generated CO₂ yielded during metamorphism of Paleozoic carbonate basement rocks. Vertical fracturing and sandstone carrier beds cause hydrocarbons from the overpressured source rocks to migrate into basement rocks and Miocene age reservoir rocks. The overpressuring has caused the gas and oil to be forced downward, upward, and laterally. At depths shallower than 2500-1800 m, the hydrocarbons (and CO₂) migrated mostly by buoyancy.

More than 26 oil and gas fields have been discovered in mostly structurally controlled accumulations. These fields have an estimated original in-place oil of 35.3 million t and in-place gas of 66.2 million m³. The amount of undiscovered resources is unknown but only a few deep (>5000 m) exploratory tests have been drilled, and exploration has just begun for stratigraphic traps.