Coupled effects of the anisotropic permeability and adsorption-induced deformation on the hydrogen and carbon reservoir extraction dynamics
Linchao Wang, Wan Zhang, Zhengzheng Cao, Yi Xue, Fei Xiong
Abstract
Hydrogen and carbon energy reservoirs, critical resources for clean energy development, require precise characterization of their mechanical and fluid flow properties. This study investigates the coupled effects of anisotropic permeability and adsorption-induced deformation on gas extraction efficiency in such reservoirs. A comprehensive numerical model is developed to integrate matrix deformation, crack anisotropy, and adsorption-driven anisotropic swelling within coal reservoirs. The model extends the Langmuir isotherm to incorporate directional adsorption effects and employs a strain-ratio mechanism to quantify permeability evolution induced by non-uniform stresses. Finite element simulations reveal that declining gas pressure near the wellbore intensifies permeability gradients. This finding underscores the necessity of accounting for adsorption-induced volumetric strain to prevent overestimation of coal permeability in traditional models. Anisotropic stress confinement significantly affects gas extraction dynamics, with horizontal permeability (ku) increasing more gradually under depletion compared to vertical permeability (kv). The results highlight pronounced directional variations in extraction rates, with x-direction rates reaching only half of those in the y direction. These findings underscore the importance of addressing permeability anisotropy and adsorption effects to optimize reservoir performance. The study offers valuable insights into the sustainable development of hydrogen and carbon energy resources, providing a theoretical foundation for enhancing gas recovery strategies.