Experiment based modeling of CO2 solubility in H2O at 313.15-473.15 K and 0.5-200 MPa

摘要

CO2 solubility data in water at subsurface temperature and pressure conditions is important in global carbon cycle research. We measured the solubility of CO2 in H2O at a wide range of temperature from 313.15 to 473.15 K, and at the pressures from 0.5 to 200 MPa, and analyzed the effect of H2O vapor in the high-pressure-high-temperature (HPHT) system. The measured solubility is remarkably similar to published data at similar pressure/temperature ranges, while greater than the calculated values of existing prediction models at HPHT. This discrepancy is caused by the unneglectable increase of H2O vapor at HPHT, i.e., the decrease of liquid H2O in the system. The experiment data also suggests the dependence of CO2 solubility on temperature and pressure varies in different pressure-temperature regions. In the low-pressure region, the solubility depends predominantly on pressure and the value is small (generally smaller than 1 mol/kg). In the intermediate pressure region, solubility depends mostly on pressure, but the dependency is less than that in the low-pressure region. In the high-pressure region, temperature outweighs pressure in influencing the solubility. The sectional model provides more accurate estimations of CO2 solubility in H2O.