Corrective measures based on pressure control strategies for CO2 geological storage in deep aquifers

A prerequisite to the wide deployment at an industrial scale of CO2 geological storage is demonstrating that potential risks can be efficiently managed. Corrective measures in case of significant irregularities, such as CO2 leakage, are hence required as advocated by the recent European directive on Carbon Capture and Storage operations. In this regard, the objective of the present paper is to investigate four different corrective measures aiming at controlling the overpressure induced by the injection operations in the reservoir: stopping the CO2 injection and relying on the natural pressure recovery in the reservoir; extracting the stored CO2 at the injection well; extracting brine at a distant well while stopping the CO2 injection, and extracting at a distant well without stopping the CO2 injection. The efficiency of the measures is assessed using multi-phase fluid flow numerical simulations. The application case is the deep carbonate aquifer of the Dogger geological unit in the Paris Basin. A comparative study between the four corrective measures is then carried using a cost-benefit approach. Results show that an efficient overpressure reduction can be achieved by simply shutting-in the well. The overpressure reduction can be significantly accelerated by means of fluid extraction but the adverse consequences are the associated higher costs of the intervention operations.