oa Smeaheia, A Potential Northern North Sea CO2 Storage Site: Structural Description And De-Risking Strategies

Smeaheia is a potential subsurface CO2 storage site located on the Horda platform in the Norwegian sector of the North Sea. The site is currently being investigated as part of the Norwegian CCS Research Centre, which envisages injection, and storage of CO2 into shallow-marine deposits comprising the Jurassic Viking Group. Two prospects, defined as fault-bound structural closures, have been identified, i) Alpha in the footwall of the Vette fault, and Beta in the Hanging wall of the Øygarden fault. In this contribution we present the fundamental structural framework of the Smeaheia site as derived from seismic interpretation of a high resolution 3D dataset. Qualitative and quantitative fault seal properties of the Vette fault are presented. Juxtaposition and shale gouge ratio analysis suggest the Vette fault has a high sealing probability for the Alpha closure. A relay zone to the south of the structure is more likely to be non-sealing and may facilitate pressure communication with a neighbouring fault block where hydrocarbon production has been ongoing. This communication may have resulted in Smeaheia being depleted. Risk of fault reactivation is assessed based on likely in-situ stress states, hydrostatic pressure regimes and the aforementioned depleted pressure regimes.