Brine geochemistry changes induced by CO2 injection observed over a 10Â year period in the Weyburn oil field

► Solubility trapping is an important geochemical trapping mechanism for injected CO2. ► Changes in downhole pH indicate ionic and solubility trapping of injected CO2. ► Increases in calcium and total alkalinity concentrations are due to ionic trapping of injected CO2. ► Geochemical monitoring provides information about time scales required for solubility and ionic trapping of injected CO2. ► Brine resistivity is used to indirectly trace movement of injected CO2 in Weyburn.