Numerical Modeling of Ground Stability Around Potential Geothermal Energy Storage Wells in a Canadian Subarctic Zone

Research over the past twenty years shows that borehole geothermal energy storage (BTES) systems are viable for heating buildings in cold climates, such as those found in Northern Quebec, Canada. However, BTES systems can increase temperatures in surrounding soil formations, potentially inducing ground deformation and causing unexpected accidents. This study objective is to investigate the effect of BTES systems with a 50-year service life on the mechanical response of surrounding soil formations in Northern Quebec, where potential BTES sites are covered by large quantities of over-consolidated soil formations. Fully coupled thermal-hydro-mechanical finite element modeling is conducted for cases with different configurations and operating temperatures. Processes of thermally induced pore pressure production and dissipation are simulated and analyzed, along with thermally induced large deformations of soil formations. Our results demonstrate that BTES systems with larger geometric scales or higher operating temperatures (60°C in this study) significantly influence ground responses, manifesting in changes of pore water pressure and ground deformations. Despite the marine soil in the studied subarctic region being over-consolidated, thermal disturbances can still result in plastic deformation when the maximum operating temperature reaches 60°C.