title: Measurement and modeling of CO₂ solubility in natural and synthetic formation brines for CO₂ sequestration.
abstract: CO2 solubility data in the natural formation brine, synthetic formation brine, and synthetic NaCl+CaCl2 brine were collected at the pressures from 100 to 200 bar, temperatures from 323 to 423 K. Experimental results demonstrate that the CO2 solubility in the synthetic formation brines can be reliably represented by that in the synthetic NaCl+CaCl2 brines. We extended our previously developed model (PSUCO2) to calculate CO2 solubility in aqueous mixed-salt solution by using the additivity rule of the Setschenow coefficients of the individual ions (Na(+), Ca(2+), Mg(2+), K(+), Cl(-), and SO4(2-)). Comparisons with previously published models against the experimental data reveal a clear improvement of the proposed PSUCO2 model. Additionally, the path of the maximum gradient of the CO2 solubility contours divides the P-T diagram into two distinct regions: in Region I, the CO2 solubility in the aqueous phase decreases monotonically in response to increased temperature; in region II, the behavior of the CO2 solubility is the opposite of that in Region I as the temperature increases.
authors.affiliation: John and Willie Leone Family Department of Energy and Mineral Engineering and ‡Department of Materials Science and Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Haining
authors.initials: H
authors.lastname: Zhao
authors.forename: Robert
authors.initials: R
authors.lastname: Dilmore
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Allen
authors.forename: Sheila W
authors.initials: SW
authors.lastname: Hedges
authors.forename: Yee
authors.initials: Y
authors.lastname: Soong
authors.forename: Serguei N
authors.initials: SN
authors.lastname: Lvov
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D057965:Carbon Sequestration; D008962:Models, Theoretical; D011312:Pressure; D012492:Salts / Q000737:chemistry*; D012995:Solubility; D013696:Temperature
chemical_list: D012492:Salts; C017082:brine; D002245:Carbon Dioxide