Study on the Evolution of Cement Properties and Mechanical Behavior in Underground Hydrogen Storage Facilities

As the global energy structure transitions toward low-carbonisation, ensuring the long-term sealing integrity of underground hydrogen storage has emerged as a critical challenge. In particular, the integrity of cement barriers in hydrogen environments is potentially threatened. This study systematically investigated the effects of hydrogen exposure on cement specimens through wave velocity, nuclear magnetic resonance (NMR), and uniaxial compression tests. These analyses revealed the physical properties and mechanical characteristics changes of cement specimens under hydrogen influence. The results indicate that hydrogen exposure slightly enhances the wave velocity of cement stones. Additionally, the total porosity of the specimens decreased due to a reduction in large pores, accompanied by a slight increase in small pores. Furthermore, the uniaxial compressive strength and Poisson's ratio of the cement specimens exhibited slight decreases, while the latter showed no substantial variation. This study elucidated the mechanical evolution patterns of hydrogen-cement interactions, thereby providing a crucial foundation for optimizing cementing materials and evaluating the integrity of hydrogen storage reservoirs.