CO2 solubility in multi-component brines containing NaCl, KCl, CaCl2 and MgCl2 at 297 K and 1–14 MPa

• CO2 solubility was measured in single and multi-component brines.
• Solubility decreases with increasing salt content in single component brines.
• Solubility depends on the salts present in solution in multi-component brines.
• Solubility becomes less sensitive to changes in pressure above 6 MPa.

Carbon capture and storage (CCS) is a strategy to reduce greenhouse gas emissions by capturing CO2 from point sources and injecting it into deep saline formations. Over time, the injected CO2 dissolves into the saline pore waters forming an aqueous solution that is both a negatively buoyant fluid (sinks) and geologically reactive. Deep saline aquifers are geochemically complex and experimental studies have several gaps in solubility measurements for the multi-component brines that are needed to model the fate and reaction of CO2. New experimental data are presented here for three of the most common salts found in potential carbon storage locations, NaCl, KCl and MgCl2, as well as multi-salt brines including these salts and CaCl2. These experimental data are compared with available literature data and models used to predict CO2 solubility in single- and multi-component brines. Comparison of the experimental data with the models indicates that the reactor does work in the range of temperature, pressure and salinity presented here and that available models can accurately predict the solubility of CO2 in various salt solutions.