A geological assessment of the carbon storage potential of structural closures in the East Midlands shelf, United Kingdom southern North Sea

Depleted gas fields and saline aquifer bearing closures of the Southern North Sea offer opportunities for subsurface CO (sub 2) storage. Fields situated in the East Midlands shelf area are especially attractive targets since they lie in shallow, coastal waters adjacent to two large industrial hubs (Humberside and Teesside). Seismic interpretation of well-calibrated, high-resolution three-dimensional seismic data sets has been combined with petrophysical analysis to identify four potential storage sites in the East Midlands shelf and evaluate their structural and stratigraphic characteristics. The sites comprise the Rough, York, and Eris fields containing Permian (Rotliegend Group) Leman Sandstone Formation reservoirs sealed by evaporites belonging to the Permian Zechstein Group. A further closure has been identified in the suprasalt section and consists of a Triassic Bunter Sandstone Formation bearing saline aquifer bearing (dry) closure. The gas fields that characterize the subsalt pose a low CO (sub 2) containment risk but exhibit heterogenous reservoir properties and variable degrees of structural compartmentalization. The suprasalt closure is substantially larger but poses a greater containment risk due to pervasive faulting within the top seal. We identify a potential cluster of depleted fields in York, Rough, and Eris that together could hold 20 MtCO (sub 2) , approximately equivalent to 1 yr's worth of the United Kingdom's intended CO (sub 2) sequestration by 2030. The study provides important new insights into the CO (sub 2) storage within depleted gas fields in the nearshore area of the Southern North Sea, the potential of which has largely been overlooked to date.