A robust and efficient numerical method for multiphase equilibrium calculations: Application to CO2-brine-rock systems at high temperatures, pressures and salinities

► We develop a method for chemical equilibrium calculations in multiphase systems. ► We show that the method is capable of determining the stable phase assemblage. ► A general approach for specifying equilibrium constraints is developed. ► The method is applied to solve equilibrium problems relevant to carbon storage. ► We demonstrate its potential to be integrated in reactive transport simulators.