Abstract: Accurately revealing the evolution patterns of pressure and temperature in salt caverns is essential for analyzing the stability and safety of hydrogen storage facilities. A model was developed to describe the evolution of temperature and pressure in the cavern, based on the thermo-hydro-mechanical coupling effects during cyclic injection and production. Additionally, methods for calculating the temperature influence zone and thermal stress in the surrounding rock were proposed. The model’s validity and accuracy were verified using on-site temperature and pressure monitoring data from the Melville salt cavern storage facility in Canada, achieving over 90% consistency. The research results indicate that, under cyclic injection and production, the temperature in the salt cavern hydrogen storage facility exhibits a wave-like periodic variation over time, described by a piecewise bi-exponential function. In contrast, the pressure varies periodically in the form of an irregular sawtooth wave, represented by a piecewise combination of linear and bi-exponential functions. Both temperature and pressure initially experience synchronous increases (during injection) or decreases (during production), followed by a synchronous stabilization phase after injection and production cease. The duration of each phase is primarily influenced by the injection and production pressures, flow rate, and the convective heat transfer effects in the surrounding rock. Under daily injection and production modes, the pressure during the stabilization phase changes very slowly in the short term, evolving into a periodic trapezoidal wave pattern. During cyclic injection and production, the surrounding rock experiences thermal stress and additional displacement due to temperature changes in the cavern. The temperature fluctuations in the salt cavern primarily affect the surrounding rock within 5 m of the cavern wall under single injection and production conditions ranging from 8 MPa to 16 MPa. Due to hydrogen’s superior heat transfer and convective efficiency, the temperature influence zone in the surrounding rock during hydrogen injection and production is significantly larger than that of other energy storage gases.

Key words: salt cavern hydrogen storage, cyclic injection and production, thermo-hydro-mechanical coupling, temperature and pressure evolution