Experimental measurements and thermodynamic modeling of CO2 solubility in the NaCl-Na2SO4-CaCl2-MgCl2 system up to 150 °C and 200 bar

International audienceTo face the climate change, the geological storage of CO2 in deep saline aquifers has been gaining interest. This study investigates the CO2 solubility in single-salt solutions containing NaCl, Na2SO4, CaCl2 and MgCl2. In a first part, an experimental campaign has been performed in an instrumented batch reactor. Acid-base and conductimetric titrations were performed. CO2 solubility points were obtained for pressure and temperature up to 20 MPa and 423.15 K. The salting-out effect has been studied (at a same ionic force of 3 mol/kg) showing the following order: SO %,CaCl 2 < SO %,MgCl 2 < SO %,NaCl < SO %,Na 2 SO 4. In parallel to laboratory experiments, a modelling work has been carried out to calculate the gas solubility. The specific numerical tool named PhreeSCALE was used. The activity coefficient has been calculated using the Pitzer formalism. Interaction parameters for the CO2-H2O-MgCl2 and CO2-H2O-CaCl2 systems were optimized successfully