Steph

Hi Jia, Many thanks for your earlier response regarding problems with modelling CO2 solubility in brine. I had actually tried the sliding fugacity method but, while it shows how the dissolved CO2 concentration changes, there seems to be no constraint on how much can be dissolved. I have tried adding as much as 10 molar CO2, all of which dissolves - something which isn't possible! I am attaching files to demonstrate what I have been trying, along with a spreadsheet illustrating the difference between the results I generated with GWB and those I obtained using Phreeqc. I hope these help clarify the problem I am having, but please do let me know if not and I'll try to explain myself better. I'd really appreciate your help with this. Many thanks, Steph 4722_dilute_test_CO2_fixed.rea 4722_dilute_test_CO2_sliding.rea GWB comparison.xlsx thermo_hmw.tdat

Hi Jia, Many thanks for your response. I had actually tried the sliding fugacity method but, while it shows how the dissolved CO2 concentration changes, there seems to be no constraint on how much can be dissolved. I have tried adding as much as 10 molar CO2, all of which dissolves - something which isn't possible! I am attaching files to demonstrate what I have been trying, along with a spreadsheet illustrating the difference between the results I generated with GWB and those I obtained using Phreeqc. I hope these help clarify the problem I am having, but please do let me know if not and I'll try to explain myself better. Many thanks, Steph GWB comparison.xlsx 4722_dilute_test_CO2_fixed.rea 4722_dilute_test_CO2_sliding.rea thermo_hmw.tdat

Hi, I am trying to calculate the maximum solubility of CO2 in a saline brine at surface and subsurface conditions. I have experimented with a number of different ways of adding CO2 to the system using React, including swapping CO2 for HCO3- or pH in the basis, and adding free CO2 as a reactant. However the results appear to indicate that the programme responds by simply reacting/dissolving as much of the gas as is initially stated, even beyond the likely point of saturation. Please can you advise me on how best to go about performing this calculation using GWB? Many thanks, Steph