A Sensitivity Study of Salt Concentration in Brine to The Solubility of CO2 in Saline Aquifers

Abstract

In CO2 sequestration, four main trapping mechanisms are expected such as structural, residual, solubility, and mineral trapping. This paper aims to analyse the impact of salt concentration in brine on the CO2 solubility trapping mechanism in the saline aquifer. The CO2 solubility decreases with salinity. In this study, a sensitivity run will be done on an existing saline aquifer dataset to investigate the impact of salt concentration using the compositional mode simulation approach. Different types of salt will give different levels of CO2 solubility in an Aqueous solution, for example, at isotherm conditions and at increasing pressure, the same amount of NaCl will be more soluble. At the same temperature condition, higher salinity will decrease CO2 solubility with pressure increases and produce a salting-out phenomenon at the near injector area. The reference dataset was completed using the black-oil simulation with the gas-water system, where the CO2 act as the gas phase and brine as the water phase. The black-oil simulator can only handle isotherm and a single salinity value, which is 200,000 ppm in this case. Thus, this study is expected to give more information and improve the solubility trapping mechanism in a saline aquifer.