@Article{fhmt.2026.078050,
AUTHOR = {Zeliang Liang, Jia Tan, Jiachao She, Fengnian Wang, Yi Wang, Donghao Li, Rugang Duan, Haotian Chu},
TITLE = {Regulation of Critical Capillary Number: High-Efficiency Displacement Mechanism of Deep Coalbed Methane Considering Wettability Heterogeneity of Proppants between Fractures},
JOURNAL = {Frontiers in Heat and Mass Transfer},
VOLUME = {},
YEAR = {},
NUMBER = {},
PAGES = {{pages}},
URL = {http://www.techscience.com/fhmt/online/detail/27605},
ISSN = {2151-8629},
ABSTRACT = {Significant wettability differences between proppants and coal matrices in deep coal reservoirs limit gas–water mass transfer, a key factor for coalbed methane recovery. This study develops a hybrid wettability fracture model using <i>in-situ</i> data, coupling Navier–Stokes equations with a phase-field method to simulate multi-scale gas–water flow. A random wettability mapping technique captures spatial heterogeneity. The critical capillary number (<i>Ca</i>)-balancing capillary and viscous forces-serves as the key threshold governing flow pathways. At low <i>Ca</i>, capillary forces dominate, causing liquid film aggregation and gas blockage; at high <i>Ca</i>, viscous forces break films and open pathways. Wettability gradients drive asynchronous phase transitions through force competition, dynamically reconstructing flow paths. We propose an optimized strategy: operating near the critical <i>Ca</i> breaks confined liquid phases, while a hydrophilic-hydrophobic balanced system enables synergistic film pre-reconstruction and secondary breakage to maximize gas transfer efficiency. This work clarifies how critical <i>Ca</i> regulates flow via wettability heterogeneity, providing a theoretical and optimization framework for enhanced mass transfer in porous media relevant to energy applications.},
DOI = {10.32604/fhmt.2026.078050}
}