Risk Assessment-led Pre-characterisation of a Site for Commercial-scale Storage of CO2

Pre-characterisation of a CO2 storage site to be suitable for a storage permit application should be led and informed by risk assessment to anticipate, reduce and mitigate risks, and monitor unmitigated risks. A multi-store site is characterised in the UK northern North Sea from publicly available data as part of the EU-funded SiteChar research project. The site comprises the Captain Sandstone, previously assessed as feasible for CO2 storage, and a hydrocarbon field hosted within it. An initial risk assessment workshop identified risks to the secure containment of CO2 within the prospective multi-store site. The list of risks was used to direct and guide technical site characterisation activities to mitigate or reduce the risks. Static geological modelling, dynamic simulation of CO2 injection and regional migration path analysis invested risks from sandstone connectivity, relationship with adjacent fault, fluid migration pathways, continuity with an underlying sandstone and porosity/permeability modelling. The results from site characterisation reduced and mitigated risks and reduced uncertainties. Pre-characterisation of a potential storage site is an essential first step in the process of permit application; a risk-led approach is an effective way to begin the process. Pre-characterisation of a potential CO2 storage site can be achieved with publicly available data.