Guidelines for aquifer monitoring programs within the frame of CO2 geological storage
Abstract
While France is committed to reduce greenhouse gas emissions, the regulatory environment requires that future geological storage sites are chosen so as to ensure environmental protection. Regulations and guidelines are available for geological storage of CO2 but guidelines towards groundwater resources are limited to brief and general recommendations. The collaborative CIPRES project (2012-2015, co-funded by the French Research Agency) was dedicated to the characterization of the potential impacts of CO2 leakage on the groundwater quality in the framework of CO2 geological storage. One main objective aimed at giving clues for the improvement of the existing guidelines in terms of freshwater aquifers monitoring methodology. A guide has been issued, summarizing the existing regulations and guidelines towards aquifers overlying geological storage of CO2 and providing a focused monitoring methodology on groundwater resources. This methodology proposes global aquifer monitoring practices, but also, for each stage of the life cycle of a geological disposal site- - basic parameters to be monitored (pH, electrical conductivity, alkalinity, major ions, DOC, dissolved CO2 groundwater level, temperature, redox potential), recommended for all aquifer in the area of review of the CO2 storage complex+ - specific parameters, which will have to be customized according to the specific context of the assessed case (based on composition of deep fluids, regional geology and hydrogeology, microbiological and geochemical parameters)+ - minimum recommendations in terms of- a) duration- prior to any storage operation, at least two years to acquire the baseline as a reference for monitoring+ b) frequency- at least 2-4 times per year for the baseline acquisitions, and 1-2 times per year during the operation monitoring+ c) and location- in the control aquifer (first aquifer above the geological storage) and vulnerable aquifers (aquifers that may suffer damages).