Impact of Hydrogen Injection on the Hydromechanical Behavior of Limestones

Underground hydrogen storage (UHS) is a promising solution to address energy storage needs associated with the intermittent nature of renewable energy production. A key challenge in UHS is to understand how hydrogen interacts with minerals in reservoir rocks, and how these chemical interactions influence their poromechanical, hydraulic and petrophysical properties. While most studies on sandstones report negligible impacts on the poromechanical evolution to H2 exposure, the effects of H2 reactions with calcite-rich limestones remain unclear. This study examines the influence of hydrogen treatment on the hydromechanical behavior of a weathered limestone through triaxial testing and hydrogen injection experiments. The findings reveal that hydrogen treatment had minimal impact on the mineral composition of the limestone. However, it increased the compressibility of their poromechanical properties. We conducted hydrogen injection experiments - both drainage and imbibition experiments to assess the residual saturation for hydrogen. These findings provide preliminary insights for advancing UHS research, focusing on enhancing mechanical stability and storage efficiency.