Modelling CO 2 solubility in pure water and NaCl-type waters from 0 to 300 °C and from 1 to 300 bar : Application to the Utsira Formation at Sleipner

Abstract

The goal of this study is to better quantify the solubility of CO 2 in brines. New experimental data on the solubility of CO 2 in a mixed salt solution at CO 2 sequestration pressure and temperature conditions are presented. A thermodynamic model for calculation of the phase equilibria of CO 2–H 2O–NaCl system is briefly described; notably, the solubility of the carbon dioxide in the aqueous phase. This model was used to check his validity by comparing the calculation results with new experimental measurements, available experimental observations and other models CO 2 solubility results. Comparison with experimental data indicates that the model can predict accurately CO 2 solubility in pure water and in aqueous NaCl solutions of ionic strengths up to 3 molal from 1 to 300 °C and from 1 to 300 bar. This model has been applied to CO 2 storage at Sleipner, North Sea. The salinity of the porewater within the Utsira Formation (the CO 2 host formation) is approximately the same as seawater. Predicted CO 2 solubility is in good agreement with new experimental measurements.