CO2-water-rock interaction by Marielle Koenen and Jan ter Heege
A short- and long-term geochemical evaluation of CO2 injection on the storage complex is required for EU regulations. The (site-specific) mineral reactions in a CO2 storage reservoir and its caprock can be investigated by different methodologies. Experimental studies give insight in the true mineral reactions, providing that the right conditions are applied, but they are per definition short-term. For the long-term geochemical models are generally used which are able to extrapolate experimental results to longer time scales and can easily assess the effects of variations in mineralogical compositions of the rocks, as well as variations in e.g. pressure and temperature conditions, formation water composition and CO2 partial pressure. However, these models are prone to significant uncertainties and they are per definition simple representations of the real, complex geological system.