CO2 storage potential of the Middle Buntsandstein in the Exclusive Economic Zone (EEZ) of the German North Sea

The storage of CO₂ in deeply buried geological formations provides an important contribution to mitigate residual emissions from heavy industry in order to limit global warming below 2 °C. Robust geological models and storage capacity estimations are crucial for the successful planning and implementation of long-term storage projects. This study focuses on the CO₂ storage potential of the Middle Buntsandstein within the Exclusive Economic Zone (EEZ) of the German North Sea. We mapped a total of 69 potential storage sites based on existing 3D models, seismic data and 39 exploration wells. Static CO₂ volumes are calculated for each structure using a Monte-Carlo-Simulation with 10.000 iterations to account for uncertainties. All potential reservoirs are evaluated based on their volume, burial depth, top seal integrity (thickness, faults) and trap type (salt-pillow and -domes, fault, stratigraphic and combined types). The best storage conditions are associated with salt-controlled anticlines on the “West Schleswig Block” with moderate burial depths, large volumes, and limited lateral flow barriers. Poor conditions are encountered in small, deeply buried (down to 7500 m), and structurally complex parts of the Horn- and Central Grabens. We identified 39 potentially technical feasible storage sites with burial depths above 4500 meters and suitable reservoir volumes (P50 confidence level above 5 Mt CO₂). The estimated total static storage capacity ranges between P90 =948 Mt, P50 = 2695 Mt and P10 =5794 Mt. This comprehensive overview about the static CO₂ storage capacities highlights the most prolific reservoirs and indicates locations for further exploration.