Depositional systems and palaeothermal history in an active rift-graben setting and its effect on hydrocarbon systems, Upper Rhine Graben, Germany

The Upper Rhine Graben (URG) in SW Germany, known as a classical hydrocarbon province in Germany and France, is part of the European Cenozoic Rift System. Active rift graben development has developed a complex sedimentary sequence of terrestrial and marine deposits. II is dominated by a thick clastic succession with several fine-grained, organic-rich units in between, providing several potential reservoir units and source rocks.

The study covers the almost the entire rift-basin fill, Upper Eocene to Lower Miocene, based on 4 wells in the northwestern URG. II aims to analyse the interaction between the active rifting and the sediment facies and paleoenvironment development and its effect on the development and quality of potential source rock units. Organic maturation is studied in addition to understand the complex palaeothermal history of this rift system and its effect on the development of active hydrocarbon plays. Palynofacies analysis suggests rapidly changing sediment facies and paleoenvironements within the sediments through time due to rapid sea level changes and a complex tectonic setting during graben formation. Based on the results of petrographic, organofacies and geochemical analysis different types of source rocks are defined. The different types of source rock are characterized regarding their depositional history and hydrocarbon prospectivity, showing the influence of the rift-controlled depositional system of the northern URG on the generation and productivity of hydrocarbon source rocks. Detailed vitrinite reflectance analysis was done in all four wells. The high-resolution maturation trends help to understand the local to regional maturation pattern and mechanisms, controlling the palaeothermal history within the complex tectonic setting of the rift- system. Long-lasting, high-temperature hydrothermal fluid systems seem to have a significant effect on organic maturation in this tectonically active setting. The combination of the results of facies and maturation analysis provides new insights into the complex interaction between development, activation and prospectivity of hydrocarbon systems and the rift-graben development in the northern URG.