The role of compartmentalisation in carbon storage site selection in the Southern North Sea

Compartmentalisation has presented significant technical challenges in the development of and production from Southern North Sea (SNS) gas fields hosting Permian (Rotliegend) reservoirs. One such field, the giant Indefatigable (Inde), has 12 distinct compartments with limited pressure communication, requiring 8 platforms and 70 production wells for development. With the explosion of prospective geological carbon storage projects around the SNS, it is likely that many compartmentalised fields will be of interest for use sequestration. However, given the present lack of value for stored carbon, storage sites need to be developed at minimal cost. As such, the impact of compartmentalisation on storage capacity and site development needs to be well understood to answer the key question: are any compartments sufficiently large to be valid as sites for carbon sequestration? In this study, Inde was evaluated for carbon storage using a traditional map-based volumetric approach, allowing the theoretical CO₂ capacity of each faulted compartment to be calculated. The results show that only five compartments have capacities larger than 10 Mt CO₂ (potentially allowing 1 Mt injection per year for 10 years). Based on theoretical capacity, the Inde compartments were ranked and a development plan of sequential filling-and-sealing was suggested.