A fill-and-spill CCS mega-fairway in the Southern North Sea: a new concept to optimise CO2 storage

Summary A potential carbon capture and storage (CCS) fill-and-spill mega-fairway is here identified in UKCS Quadrants 43-44, by combining regional wellbore data with 3D seismic interpretation and migration modelling. In the study area, the Triassic Bunter Sandstone reservoir shows consistent thicknesses (90-216 m) and prospective core-based porosities and permeabilities (11-28%, 9-669 mD). A connected reservoir is suggested regionally from consistent, near-hydrostatic aquifer pressure gradients (~0.51 psi/ft) and leakage is mitigated through a thick, laterally-effective top seal. Structural closures in the area are generally less than the CO2 column heights necessary to breach the seal. At least eleven mapped closures are shown to link together into the proposed regional fill-and-spill “Silverpit CCS Fairway”. If filled to spill, these traps could cumulatively host up to 7.9 Gt of CO2, three times that of the proposed Endurance CCS Field. Through management of the injection and fill-spill strategy, this fairway could be future-proofed in relation to CO2 spill hazards, whilst possibly requiring less ‘injector hubs’ to fill the traps. Migration spill-point modelling along the fairway may also inform the placement of permanent, cost-effective multi-physics seabed system for leakage and migration monitoring. Exploiting fill-and-spill fairways for CCS is a new concept with vast potential applicability globally.