Safety Criteria Definition for CO2 Geological Storage

Addressing safety concerns is crucial for large-scale implementation of CO2 geological storage. This raises many challenges, such as time scales, uncertainties and variability. We try to demonstrate a methodology to establish safety criteria, which are necessarily site-specific. An application for storage in aquifer underneath the Paris Basin supports the exercise. For establishing risk scenarios, nine types of targets have been listed, as well as eleven risk events sorted into five categories. These generic lists constitute a basis for an expert panel to screen a site. The identified scenarios are simulated in terms of effect properties of the risk events. Integrating the outcomes in a site model figuring the stakes shall allow inferring requirements to maintain targets exposure below levels conducting to significant impacts. Simple modelling is favoured: analytical solutions are investigated for the expected behaviour or for well leakage; a semi-analytical model and related abacuses for cap rock fracturing; some events require more elaborated numerical models. Studying the influence of uncertainties is facilitated by using such simple models. Further work includes effectively deducing safety criteria for the application site.