Impact of thermo-hydro-mechanical process coupling for CO2-water multiphase flow during geothermal energy extraction

Abstract This study investigates the potential of multiphase water - carbon dioxide (CO 2 ) systems for geothermal energy extraction, emphasizing their enhanced efficiency and reduced environmental impact. Through numerical simulations, it explores the coupled thermo-hydro-mechanical (THM) processes that influence reservoir behavior. During operation, the pressure distribution evolves, reflecting CO 2 plume maturation, while temperature and permeability changes highlight the importance of coupled THM processes in predicting mechanical response and fluid dynamics. The study also exemplifies the impact of reservoir heterogeneity, showing how THM driven variations in permeability, porosity, and capillary entry pressure affect heat extraction and CO 2 distribution. Sensitivity analysis identifies key factors such as injection rate, wellbore perforation length, reservoir thickness, permeability and initial temperature as critical to CO 2 trapping, energy extraction, surface deformation and pressure development. These findings emphasize the need for fully coupled THM models to ensure accurate reservoir behavior predictions and effective geothermal energy system design. • A fully coupled THM multiphase water - CO 2 systems for geothermal energy extraction is modeled. • THM modeling is needed over TH and HM coupled modeling for accuracy. • Sensitivity analysis identifies the importance of operational and geological features. • CO 2 trapping, energy extraction, surface deformation and pressure development are assessed.