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

The utilisation of extensive saline aquifers for CO₂ storage will require careful consideration of the potential pressure responses. Displacement of formation waters result 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 United Kingdom Southern North Sea (UKSNS) was investigated by structural interpretation of seismic data. A new classification scheme was developed to characterise 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 potential 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 CO₂ storage in the UKSNS and to maximise storage capacity. The methodology can also be applied to other regions where extensive saline aquifers are considered for CO₂ storage.