The Miocene petroleum system of the Sava Depression, Croatia

The Sava Depression, located on the southern margin of the Pannonian Basin, contains a number of small oil and gas fields. The depression is filled pr incipally with Neogene sediments resting on Palaeozoic crystalline basement . Rifting occurred in Early to Middle Miocene times. Geochemical data imply that Middle to Upper Miocene pelites are good oil-prone source rocks. Most of the oil and oil-gas fields are situated at depths of 370 to 2300 m. Wea thered basement rocks and Miocene conglomerates and sandstones are reservoi r rocks and the fields are mostly structural and/or structural-stratigraphi c traps. Oils from the fields correlate well with the identified source roc k facies and maturity level and we propose short migration distances. Sava oil properties show variations in bulk and specific parameters that can be attributed to post-generative processes.