To investigate the characteristics and mechanisms of gas migration and to predict the effective gas permeability in saturated bentonite within deep geological repositories, water saturation, gas injection, and mercury intrusion porosimetry (MIP) tests were conducted on GMZ bentonite specimens under a confining pressure of 8 MPa, taking temperature effects into account. The results indicate that the intrinsic permeability measured with water increases as temperature rises. During the gas injection test, the gas pressure recorded downstream exhibits a three-stage evolution process. Gas displaces pore water and induces pore shrinkage in the specimen, with the shrinkage ratio varying with temperature. As the gas injection pressure increases, mechanical gas breakthrough may ultimately be triggered by pore expansion. At the same injection pressure, effective gas permeability increases with rising temperature. A prediction model for effective gas permeability was developed based on the water-measured intrinsic permeability and the Hagen-Poiseuille model, validated by considering the influences of temperature, the Klinkenberg effect, and gas injection pressure.
Li et al. (Thu,) studied this question.
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