Source Rock Distribution in the Drava Depression, Pannonian Basin, Croatia

The DR-02 exploration area is extremely heterogeneous in terms of environment and facies due to its extremely dynamic position in the geological past. The overall source rock average TOC is relatively low. The HI values vary in an extremely wide range (from less than 10 to 700 mg HC/ g TOC) as a reflection of organic matter type and/or thermal maturity. Source rock distribution, types of organic facies as well as redefined hydrocarbon potential are demarcated throughout DR-02 sedimentological model. The facies of the source rocks are related to marine (shallow and deep-water), transitional and lake (brackish-freshwater) environments. Lithologically they are dominated by marls, calcite-rich marls and mudstones. The variable relations of aquatic and terrestrial organic matter reflect these environments and conditions during deposition.