Top Seal Analysis for CO2 Storage in the Vienna Basin: Static and Dynamic Properties

Summary Geological storage of CO2 (CCS) will be needed to reduce the impact of anthropogenic climate change. While the technical feasibility of the technology is proven, social acceptance remains low. Especially onshore storage needs transparent integrity analyses during approval procedures. This study therefore aims at providing a view on the CO2 seal capacity of mudstones in the Vienna Basin, a potential target area for future onshore CCS in Austria. In a first step, static CO2 seal capacity was evaluated based on wireline log-derived porosity vs. depth trends. Secondly, dynamic mass flux rates and breakthrough times for processes potentially causing a CO2 breakthrough into the seal were calculated. Lastly, mineralogical changes in a seal layer over time spans of 1000–100000 a were investigated. For both static and dynamic sealing scenarios it is indicated that seal capacity in the Vienna Basin is high and storage risks associated with top seal integrity are likely negligible.