Keywords

CO2 geological sequestration, solubility, PR-EOS, KK-equation

Location

Session H5: Systems Modeling and Climate Change: A systematic Methodology for Disentangling Elements of Vulnerability, Adaptation and Adaptive Capacity

Start Date

16-6-2014 3:40 PM

End Date

16-6-2014 5:20 PM

Description

Injecting CO2 into deep saline aquifers possesses the highest potential capacity for geological carbon storage (GCS) in order to mitigate climate change. CO2 solubility in salty aqueous solutions plays a key role in GCS. However, the models of CO2 solubility are scanty when the mixture of K+, Na+, Ca2+ and Mg2+ in aqueous solution is included. In this study, a simple model for CO2 solubility is proposed covering conditions typically encountered in geological sequestration. Effect of the property and concentration of K+, Na+, Ca2+ and Mg2+ on the solubility of CO2 is quantified based on the behavioral featers of solubility data. In order to describe CO2-brine phase equilibrium, the Peng-Robinson equation of state (PR-EOS) and Krichevsky-Kasarnosky equation (KK equation) are applied. The (PR-EOS) is modified for better performance in high salinity brine. The Henry's constant is precisely described by temperature and concentration of the mixed ions. A linear correlation is also found between the partial molar volume of CO2 and the ions in aqueous solution at a given temperature. The relationship can be represented by parameters optimized with least squares approach. The predicted solubility of CO2 in pure water and aqueous NaCl solutions are well validated at the temperature and pressure ranges of 313-453 K and 8-50 MPa, where adequate experimental measurements are given. In terms of salty aqueous solutions with mixed ions, desirable agreement is achieved between this model and the literature data, making our work possess theoretical and practical significance to the GCS.

 
Jun 16th, 3:40 PM Jun 16th, 5:20 PM

Modeling of CO2 Solubility in Salty Aqueous Solutions at Geological Sequestration Conditions

Session H5: Systems Modeling and Climate Change: A systematic Methodology for Disentangling Elements of Vulnerability, Adaptation and Adaptive Capacity

Injecting CO2 into deep saline aquifers possesses the highest potential capacity for geological carbon storage (GCS) in order to mitigate climate change. CO2 solubility in salty aqueous solutions plays a key role in GCS. However, the models of CO2 solubility are scanty when the mixture of K+, Na+, Ca2+ and Mg2+ in aqueous solution is included. In this study, a simple model for CO2 solubility is proposed covering conditions typically encountered in geological sequestration. Effect of the property and concentration of K+, Na+, Ca2+ and Mg2+ on the solubility of CO2 is quantified based on the behavioral featers of solubility data. In order to describe CO2-brine phase equilibrium, the Peng-Robinson equation of state (PR-EOS) and Krichevsky-Kasarnosky equation (KK equation) are applied. The (PR-EOS) is modified for better performance in high salinity brine. The Henry's constant is precisely described by temperature and concentration of the mixed ions. A linear correlation is also found between the partial molar volume of CO2 and the ions in aqueous solution at a given temperature. The relationship can be represented by parameters optimized with least squares approach. The predicted solubility of CO2 in pure water and aqueous NaCl solutions are well validated at the temperature and pressure ranges of 313-453 K and 8-50 MPa, where adequate experimental measurements are given. In terms of salty aqueous solutions with mixed ions, desirable agreement is achieved between this model and the literature data, making our work possess theoretical and practical significance to the GCS.