Analysis of fluid migration pathways in the context of CO2 underground storage in the German North Sea using high-resolution 3D and 2D seismic data

For successful and safe underground CO₂ storage, a profound knowledge of the subsurface and its geological structures characterizing the selected reservoir is essential. Besides robust geological models and storage capacity estimations, seal integrity analysis and the identification of potential seal-bypass systems is crucial to ensure save long-term storage of CO₂ in the deep subsurface. Within the framework of the GEOSTOR project, we assess potential Triassic and Jurassic CO₂ reservoirs by analysing the integrity of overlying barrier formations below the German North Sea. For this purpose, we use recently acquired high-resolution 3D seismic data covering an area of 94 km² within the northwestern German North Sea (“Entenschnabel”) and high-resolution 2D seismic data from the central German North Sea (“West Schleswig Block”) covering a total length of about 1500 km. Seismic amplitude anomalies indicate the presence of fluids allowing the investigation of former fluid migration pathways and their connection to faults and salt structures. First results from the “Entenschnabel” show a highly resolved 3D image from the seafloor to the Zechstein covering the salt diapir Belinda. Bright spots indicate fluid migration along the crestal fault system. Direct fluid migration indicators are scarce within the West Schleswig Block. Locally, bright spots indicate fluid migration along crestal faults of salt structures. We compare and discuss the characteristics of identified fluid migration pathways near the salt diapir Belinda with fluid migration and its correlation with faults and salt structures from the central German North Sea in the context of barrier integrity for subsurface CO₂ storage.