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<p>Methane in situ explosive fracturing (MISEF) aims to create efficient fracture channels in perforations by utilizing detonation loading to facilitate methane migration, yet the confined propagation of methane–oxygen explosive loading and its control on through-going fracture formation in bedding shale remain insufficiently understood. In this study, core-scale methane–oxygen explosive fracturing experiments were combined with high-fidelity numerical simulations to investigate the multiscale fracture evolution and dynamic failure mechanism of bedding shale. Post-fracturing fracture networks were quantitatively characterized using μ-CT three-dimensional reconstruction, fracture surface morphology analysis, multifractal characterization, and seepage evaluation. A physically consistent explosive-loading model was further established by coupling a modified JWL equation of state with a bedding-resolved shale constitutive model, enabling the reproduction of explosive-wave propagation, reflection, superposition, and stress evolution within the explosion tube–shale borehole system. The results indicate that, under low confining pressure, explosive loading induces a three-dimensional fracture network dominated by a bedding-controlled through-going main fracture and supplemented by secondary bedding-parallel fractures, whereas elevated confining pressure markedly suppresses fracture propagation and connectivity. Increasing explosion intensity enhances fracture volume, connectivity, and spatial complexity, while the pore–throat system within the through-going fracture evolves from fine short-range channels to a composite network with multiscale apertures and flow pathways. Multifractal and seepage analyses reveal that fracture complexity is mainly intensified in localized high-damage zones rather than through uniform spatial expansion, and that through-going fractures serve as preferential flow conduits. Numerical results further show that confined explosive waves sustain energy transmission through reflection-induced amplification, generating coupled radial compressive and hoop tensile stresses perpendicular to bedding, while fracture initiation and coalescence along bedding planes are governed by short-duration, high-amplitude hoop tensile stress pulses. This study clarifies the dynamic mechanism of bedding-controlled through-going fracture formation and provides a mechanistic basis for optimizing MISEF in bedding shale.</p>

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Dynamic Mechanisms and Multiscale Characterization of Bedding-Controlled Fracture Formation Driven by Methane Explosive Loading

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Yabo Chai,
  • Ning Luo,
  • Cheng Zhai,
  • Yucheng Wei,
  • Jianan Zhou,
  • Guofeng Liang,
  • Yu Wang

摘要

Methane in situ explosive fracturing (MISEF) aims to create efficient fracture channels in perforations by utilizing detonation loading to facilitate methane migration, yet the confined propagation of methane–oxygen explosive loading and its control on through-going fracture formation in bedding shale remain insufficiently understood. In this study, core-scale methane–oxygen explosive fracturing experiments were combined with high-fidelity numerical simulations to investigate the multiscale fracture evolution and dynamic failure mechanism of bedding shale. Post-fracturing fracture networks were quantitatively characterized using μ-CT three-dimensional reconstruction, fracture surface morphology analysis, multifractal characterization, and seepage evaluation. A physically consistent explosive-loading model was further established by coupling a modified JWL equation of state with a bedding-resolved shale constitutive model, enabling the reproduction of explosive-wave propagation, reflection, superposition, and stress evolution within the explosion tube–shale borehole system. The results indicate that, under low confining pressure, explosive loading induces a three-dimensional fracture network dominated by a bedding-controlled through-going main fracture and supplemented by secondary bedding-parallel fractures, whereas elevated confining pressure markedly suppresses fracture propagation and connectivity. Increasing explosion intensity enhances fracture volume, connectivity, and spatial complexity, while the pore–throat system within the through-going fracture evolves from fine short-range channels to a composite network with multiscale apertures and flow pathways. Multifractal and seepage analyses reveal that fracture complexity is mainly intensified in localized high-damage zones rather than through uniform spatial expansion, and that through-going fractures serve as preferential flow conduits. Numerical results further show that confined explosive waves sustain energy transmission through reflection-induced amplification, generating coupled radial compressive and hoop tensile stresses perpendicular to bedding, while fracture initiation and coalescence along bedding planes are governed by short-duration, high-amplitude hoop tensile stress pulses. This study clarifies the dynamic mechanism of bedding-controlled through-going fracture formation and provides a mechanistic basis for optimizing MISEF in bedding shale.