https://doi.org/10.1140/epjp/s13360-025-07247-3
Regular Article
Mechanisms of gas–water relative permeability evolution in rough fractures: the coupling controls of shear displacement and confining pressure
1
Shanxi Railway Vocational and Technical College, 030013, Taiyuan, Shanxi, China
2
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, 174 Shazhengjie Street, Shapingba District, 400044, Chongqing, China
3
Geofluids, Geomechanics and Geoenergy (3G) Research Group, Chongqing University, 400044, Chongqing, China
a
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Received:
4
November
2025
Accepted:
20
December
2025
Published online:
13
January
2026
Abstract
To investigate the two-phase flow patterns in rough fractures under the coupled effects of in situ confining pressure and shear displacement, this study selected shale samples from Sichuan for seepage experiments. The findings reveal that for both mated and non-mated fractures, increased confining pressure leads to fracture closure, significantly reducing the equivalent hydraulic aperture. However, under identical confining pressure, the equivalent hydraulic aperture of non-mated fractures remains significantly higher than that of mated fractures. As confining pressure increases and fractures close, the local flow paths of the two-phase fluids change, interfacial resistance increases, and the relative permeability of the water phase shows a marked downward trend. Shear displacement effectively expands flow channels within fractures. When shear displacement reaches 0.6 mm, the relative permeability of the water phase increases by 80%, while that of the gas phase increases by 40%. Based on the analysis of relative permeability evolution under the combined effects of fracture roughness, confining pressure, and shear displacement, we established a relative permeability prediction model accounting for these factors. This model accurately describes the flow behavior of two-phase fluids in rough rock fractures under varying confining pressures and shear displacements.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
