Experimental and Numerical Simulation of the Injection of a CO2 Saturated Solution in a Carbonate Reservoir: Application to the CO2-DISSOLVED Concept Combining CO2 Geological Storage and Geothermal Heat Recovery

Abstract : The CO2-DISSOLVED project explores the technical and economic feasibility of a promising concept combining CO2 storage and geothermal heat extraction. The CO2 released by low CO2 emitters is dissolved in the extracted brine via a doublet heat exchanger system. To study the effect to CO2-rich and thus acidic solution in the geothermal doublet, three reactive flow-through experiments mimicking the injection of a CO2 rich solution were performed. The chemical interactions in the near-injection well area between the reservoir rock, the cement phases and the acidic CO2-rich solution was investigated under geothermal reservoir conditions. The main results are i) the formation of a highly permeable network due to specific dissolution pattern called wormholes, and ii) the preservation of mechanical cohesion the cement/rock interface despite the cement carbonation. The experimental results are compared with those obtained by chemical-transport modelling with the coupled PHREEQC-MARTHE codes.