Structural controls on pressure communication across the Bunter Sandstone Formation, UK Southern North Sea

Abstract

The utilization of extensive saline aquifers for CO 2 storage will require careful consideration of the potential pressure responses. The displacement of formation waters results in far-reaching pressure footprints that extend beyond the storage sites. Where multiple storage projects share a connected saline aquifer, the available pressure budgets for neighbouring projects may be negatively impacted. Structures such as faults and salt walls can potentially divide an aquifer into smaller hydraulic units. The extent of hydraulic units in the Bunter Sandstone Formation (BSF) within the UK Southern North Sea (UKSNS) was investigated by structural interpretation of seismic data. A new classification scheme was developed to characterize the major structural features affecting the BSF and their likely impact on boundary conditions. The resultant boundary condition map indicates where structures are expected to inhibit pressure communication through displacement/dislocation of the BSF aquifer. The results were validated by pressure data, which confirmed the existence of variable pressure regimes across the BSF. Understanding these boundary conditions is essential to support the strategic deployment of CO 2 storage in the UKSNS and to maximize storage capacity. The methodology can also be applied to other regions where extensive saline aquifers are considered for CO 2 storage