Quantitative Raman Spectroscopic Measurements of CO2 Solubility in NaCl Solution from (273.15 to 473.15) K at p = (10.0, 20.0, 30.0, and 40.0) MPa

The knowledge of high pressure phase behavior of the CO2–H2O–NaCl system in a wide T–P–mNaCl range is of great interest in the injection of CO2 to deep reservoir for storage or enhancement of oil recovery (EOR). The calculation of CO2 solubility in brine is very important to predict the CO2 storage capacity in saline aquifers. However, CO2 solubility data at high salinity and high pressure are limited, and few thermodynamic models can accurately predict CO2 solubility when salinity is higher than 4.5 mol/kg. In this study, a noninvasive technique, quantitative Raman spectroscopy, was used to investigate the high pressure equilibria of the CO2–H2O–NaCl system. A total of 180 solubility data points were obtained for carbon dioxide in (1, 3, and 5) mol/kg NaCl solutions from (273.15 to 473.15) K up to 40 MPa. New parameters were derived to improve the Duan-type solubility model, thus it can be applied in CO2 sequestration and EOR to accurately calculate the solubility of CO2 in NaCl aqueous solution up to 6 mol NaCl/kg H2O from (273 to 473) K, (3 to 60) MPa.