Petroleum System of the Palaeozoic - Mesozoic Strata in the Basement of Central Part of the Polish Carpathians

Abstract

The geochemical characteristic of the Palaeozoic - Mesozoic strata in the cross-border of the Upper Silesian and Malopolska blocks in the basement of the Polish Carpathians determined the Devonian and Carboniferous source rocks as the best source for hydrocarbon generation. The oil-condensate-source rocks correlations indicated the source of the Łąkta gas field and the Grobla oil field. The maturity modelling revealed that the Devonian source rocks reached a late phase of “oil window”, and locally ”gas window”. The Carboniferous source rock was mature enough to start the generation processes. The generation started in the late Carboniferous, but the main phase of the petroleum processes took place in Paleogene and Neogene. The expulsion was observed only in the Devonian source rocks. Vertical migration by fault system in both blocks mainly during Neogene resulted in oil and gas accumulation in the Upper Jurassic carbonates and Upper Cretaceous sandstones. The petroleum modelling indicated the Devonian source for oil and gas fields in the study area. However, condensate-source rock correlation also suggests the presence of the Carpathian flysch source for hydrocarbons accumulated in the Łąkta field.