Regional pressure response to large-scale carbon storage in the bunter sandstone formation, Silverpit Basin (Southern North Sea, UK)

Carbon Capture and Storage (CCS) technologies play a pivotal role in mitigating anthropogenic carbon emissions by enabling the long-term subsurface sequestration of CO₂. These are essential for achieving international climate targets and supporting short- to mid-term mitigation strategies. Among potential storage sites, the extensive saline aquifer of the Bunter Sandstone in the Silverpit Basin has been identified as a high-capacity reservoir suitable for CCS deployment. With more CO₂ injection projects planned, understanding the broader aquifer sensitivity is essential. This study investigates the influence of geological settings and boundary transmissibility on the aquifer response to large-scale CO₂ injection. A regional model of the Silverpit was developed to simulate CO₂ injection at a rate of 1 Mt/yr/well over 50 years across 14 wells, followed by a 5000-year post-injection observation period to assess plume migration and pressure behaviour. The findings indicate that the reservoir can safely accommodate approximately 700 Mt of supercritical CO₂. However, pressure footprint extends over tens of kilometres, underscoring the necessity of accurately characterising regional boundaries. Moreover, the latter significantly influences inter-regional flow dynamics, with observed inversions in flow direction. The structural setting of the Silverpit ensures effective CO₂ containment within four-way dip closures. A thorough understanding of these interactions is crucial for evaluating the potential need for brine production to manage reservoir pressure and mitigate pressure interference between storage licenses.