Modeling mass transfer of CO_2 in brine at high pressures by chemical potential gradient  

作　　者：JI YuanHui JI XiaoYan LU XiaoHua TU YongMing 

机构地区：[1]Division of Energy Science,Lule University of Technology [2]State Key Laboratory of Materials-Oriented Chemical Engineering,Nanjing University of Technology [3]Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education,Southeast University [4]Division of Structural Engineering and Bridges,Royal Institute of Technology (KTH)

出　　处：《Science China Chemistry》2013年第6期821-830,共10页中国科学（化学英文版）

基　　金：Lule University of Technology for the financial support ;the financial support from the Swedish Research Council;the National Basic Research Program of China (2009CB226103,2009CB623400);the National Natural Science Foundation of China(50808039);the Natural Science Foundation of Jiangsu Province,China (BK2009138)

摘　　要：To investigate long-term CO2 behavior in geological formations and quantification of possible CO2 leaks, it is crucial to inves- tigate the potential mobility of CO2 dissolved in brines over a wide range of spatial and temporal scales and density distribu- tions in geological media. In this work, the mass transfer of aqueous CO2 in brines has been investigated by means of a chemi- cal potential gradient model based on non-equilibrium thermodynamics in which the statistical associating fluid theory equa- tion of state was used to calculate the fugacity coefficient of CO2 in brine. The investigation shows that the interracial concen- tration of aqueous CO2 and the corresponding density both increase with increasing pressure and decreasing temperature; the effective diffusion coefficients decrease initially and then increase with increasing pressure; and the density of the CO2-disolved brines increases with decreasing CO2 pressure in the CO2 dissolution process. The aqueous CO2 concentration profiles obtained by the chemical potential gradient model are considerably different from those obtained by the concentration gradient model, which shows the importance of considering non-ideality, especially when the pressure is high.To investigate long-term CO2 behavior in geological formations and quantification of possible CO2 leaks, it is crucial to investigate the potential mobility of CO2 dissolved in brines over a wide range of spatial and temporal scales and density distributions in geological media. In this work, the mass transfer of aqueous CO 2 in brines has been investigated by means of a chemical potential gradient model based on non-equilibrium thermodynamics in which the statistical associating fluid theory equation of state was used to calculate the fugacity coefficient of CO2 in brine. The investigation shows that the interfacial concentration of aqueous CO2 and the corresponding density both increase with increasing pressure and decreasing temperature; the effective diffusion coefficients decrease initially and then increase with increasing pressure; and the density of the CO2 -disolved brines increases with decreasing CO2 pressure in the CO2 dissolution process. The aqueous CO2 concentration profiles obtained by the chemical potential gradient model are considerably different from those obtained by the concentration gradient model, which shows the importance of considering non-ideality, especially when the pressure is high.

关 键 词：C02 geological sequestration DISSOLUTION non-equilibrium thermodynamics mass transport DIFFUSION DENSITY SAFTEoS 

分 类 号：X701[环境科学与工程—环境工程]