Reservoir quality of Middle and Upper Triassic carbonate rocks of the Kraichgau area (SW Germany)

Open fractures in tight rocks are most likely the preferred fluid pathway in the subsurface and are therefore of interest in e.g., geothermal energy production, and gas and oil production. Natural fractures in Middle and Upper Triassic carbonate rocks of the Kraichgau area in Southern Germany are studied in a quarry on the eastern Upper Rhine Graben shoulder and show at minimum three main striking direction. Preliminary results on petrophysical measurements on plug samples show low porosity and permeability values (max. 10.9% and max. 0.0118 mD). Additionally, the diagenetic influence on petrophysical properties is analyzed. Diagenetic processes cause cementation and dissolution of minerals and influence petrophysical properties. Fracture analysis in combination with rock classification and the interpretation of the diagenetic history and the influence on petrophysical properties provide a better understanding on reservoir properties and thus limit exploration risks. Furthermore, the study location shows compressional deformation in form of decameter-sized kink bands, and veins composed of different generations of carbonate cements.