CO2 Dissolution in the reservoir brine: An experimental and simulation-based approach

This study benefits from carbon dioxide gas (CO2) dissolution experiments to mimic CO2 dissolution behavior under reservoir conditions. A unique experimental setup, consisting of a batch reactor, gas flow meter, and a sampling separator, was used to measure CO2 dissolution in the geothermal brine at various temperatures (20 degrees C to 142 degrees C) and pressures (1 barg to 13 barg). The CO2 was measured using a gas flowmeter and alkalinity tests. It was observed that the experiments' results matched with a PHREEQC model and empirical correlations available in the literature with R-square values more than 0.86. Water salinity and gas impurity effects on CO2 dissolution were investigated using a calibrated PHREEQC model. CO2 dissolution enhanced mineral solubility such as gypsum, calcium, dolomite, and halite. The study also investigated CO2 dissolution kinetics using batch experiments. The pressure behavior of the gas-brine mixture showed the importance of complete mixing to reach the maximum gas dissolution in the brine. The mixing process showed that at least 2000 s of mixing is required to achieve the maximum dissolving capacity of the geothermal brine at the experiment conditions. The novelty of the study is using real reservoir gas and reservoir brine for CO2 dissolution experiments in a unique experimental setup. Therefore, it will provide insight for CO2 sequestration in geothermal reservoirs.