Evaluation of low- to moderate-enthalpy shallow sedimentary reservoirs for CCS-CPG systems

Combining geothermal energy extraction from hydrothermal sedimentary reservoirs with carbon capture and storage (CCS) can be very beneficial to recover initial costs. Numerous thermal power plants and other CO₂-producing industries are globally located in low- to moderate-enthalpy hydrothermal reservoirs. Previous studies on the modeling of combined CO₂ plume geothermal (CPG) and CCS systems have focused on deeper and hotter reservoirs and highlighted the advantage of higher CO₂ mobility compared to water. Using reservoir simulations, we demonstrate that significant variations of CO₂ density, mobility, and heat capacity with temperature (between 30°C and 80°C) and pressure (around 10 MPa) contribute to improved energy production and CO₂ sequestration in low-enthalpy and shallow reservoirs. In a 125°C reservoir, energy production is reduced after the CO₂ plume reaches the production well. However, this does not happen in a 75°C reservoir due to the higher CO₂ heat capacity between 35°C and 55°C. After CPG, for higher reservoir temperatures, the dissolution rate is lower as the CO₂ solubility decreases with temperature, but the CO₂ plume migrates faster.