Modeling of Hydrogeochemical Processes of Carbon Dioxide Interaction with Formation Water and Rock Minerals During Enhanced Oil Recovery and Underground storage

Application of hydrogeochemical modeling using PHREEQC software to study interaction of formation water, carbon dioxide and reservoir rock minerals during CO 2 injection for enhanced oil recovery or underground storage is discussed. Hydrogeochemical modeling is a powerful tool to evaluate the physicochemical processes occurring in the "gas phase – aqueous solution – solid phases" system depending on initial parameters such as temperature, pressure and reactant concentrations. The use of hydrogeochemical simulators provides a wide range of opportunities to analyze the processes of dissolution and precipitation of minerals, changes in the ionic composition and pH of the solution, which can affect the efficiency of CO 2 injection, fluid flow, well and equipment operation. A step-by-step method for modeling interactions in the "formation water – CO 2 – rock" system using the PHREEQC hydrogeochemical simulator provides good reproducing accuracy for the results of laboratory experiments and analysis of their correspondence to the processes occurring under different conditions. The obtained results are useful for optimization of oil and gas production processes involving carbon dioxide, planning and stability assessment of underground carbon dioxide storage facilities and other geological applications.