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<p>Methane deflagration fracturing is an emerging stimulation technique that enhances reservoir permeability by igniting a mixture of injected combustion aids and in situ methane to generate detonation waves, thereby creating complex fracture networks. However, the existing experimental studies have predominantly focussed on open-hole wells, paying insufficient attention to wellbore integrity. This study systematically examines the failure mechanisms of cement sheath integrity during methane deflagration fracturing and proposes optimization strategies based on the large-scale unconfined deflagration experiments and 3D finite element simulations. The mechanical properties of oil well cement and shale-like materials, along with interfacial bond strengths, were first characterized. Deflagration experiments under varying initial pressures were conducted on perforated wellbores, with real-time pressure monitoring and post-test integrity evaluation. A corresponding 3D numerical model was developed and validated experimentally. Results show that detonation waves propagate directionally through perforations, generating fractures aligned with the 60° perforation phasing and forming radially and axially extended fracture networks. Simulations reveal complete debonding at the casing–cement interface due to insufficient tensile bond strength, and full debonding at the cement–formation interface within perforation zones, though bonding remains intact outside these areas. Parametric analysis indicates that larger perforation diameters and higher initial pressures increase fracture complexity, damage extent, and debonding area. Mitigation strategies—such as toughened cement systems, optimized perforation parameters, and controlled deflagration pressures—are proposed to maintain wellbore integrity. This study confirms the feasibility of rationally designing fracturing devices and demonstrates the technical potential of methane deflagration fracturing, providing crucial theoretical and practical guidance for field applications.</p>

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Evaluation of Perforated Wellbore Integrity During Methane Deflagration Fracturing by Integrating Large‑Scale Experiments and Numerical Simulations

  • 期刊论文

  • 发表日期：

    2025年9月26日

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  • Kun Jiang,
  • Shouchun Deng,
  • Weiqi Li,
  • Xiaofang Jiang,
  • Yixuan Li,
  • Haibo Li

摘要

Methane deflagration fracturing is an emerging stimulation technique that enhances reservoir permeability by igniting a mixture of injected combustion aids and in situ methane to generate detonation waves, thereby creating complex fracture networks. However, the existing experimental studies have predominantly focussed on open-hole wells, paying insufficient attention to wellbore integrity. This study systematically examines the failure mechanisms of cement sheath integrity during methane deflagration fracturing and proposes optimization strategies based on the large-scale unconfined deflagration experiments and 3D finite element simulations. The mechanical properties of oil well cement and shale-like materials, along with interfacial bond strengths, were first characterized. Deflagration experiments under varying initial pressures were conducted on perforated wellbores, with real-time pressure monitoring and post-test integrity evaluation. A corresponding 3D numerical model was developed and validated experimentally. Results show that detonation waves propagate directionally through perforations, generating fractures aligned with the 60° perforation phasing and forming radially and axially extended fracture networks. Simulations reveal complete debonding at the casing–cement interface due to insufficient tensile bond strength, and full debonding at the cement–formation interface within perforation zones, though bonding remains intact outside these areas. Parametric analysis indicates that larger perforation diameters and higher initial pressures increase fracture complexity, damage extent, and debonding area. Mitigation strategies—such as toughened cement systems, optimized perforation parameters, and controlled deflagration pressures—are proposed to maintain wellbore integrity. This study confirms the feasibility of rationally designing fracturing devices and demonstrates the technical potential of methane deflagration fracturing, providing crucial theoretical and practical guidance for field applications.