China Safety Science Journal ›› 2025, Vol. 35 ›› Issue (4): 51-58.doi: 10.16265/j.cnki.issn1003-3033.2025.04.1040

• Safety engineering technology • Previous Articles     Next Articles

Study on explosion overpressure and deflagration-to-detonation transition characteristics of shale gas in fractures

SHAO Hao1,2(), CAI Yi1,2, YANG Tao3,**(), WU Zhengyan1,2, HU Huan1,2, YAO Zhiyuan1,2   

  1. 1 School of Safety Science Engineering Management, China University of Mining and Technology, Xuzhou Jiangsu 221116, China
    2 National Engineering Research Center for Coal Mine Gas Control, China University of Mining and Technology, Xuzhou Jiangsu 221116, China
    3 School of Mining Safety, North China Institute of Science and Technology, Langfang Hebei 065201, China
  • Received:2024-12-05 Revised:2025-02-27 Online:2025-04-28 Published:2025-10-28
  • Contact: YANG Tao

Abstract:

To investigate the methane DDT distance and maximum explosion pressure (Pmax) in shale fractures, a multi-scale adjustable 3D planar slit detonation system was developed. Experiments with methane-oxygen premixed gas under 4 different hydraulic diameters, along with numerical simulations, were conducted to examine shale gas combustion under high pressure. Results show that methane-oxygen premixed gas can sustain self-propagating explosion within a hydraulic diameter range of 1.9 to 11.43 mm. Both Pmax and peak pressure rise rate increase linearly with initial pressure. Under a hydraulic diameter of 11.43 mm, Pmax closely approaches theoretical detonation pressure. As the hydraulic diameter decreases, the Pmax-to-initial pressure ratio decreases. The initial pressure and the DDT distance follow a power-law relationship. Increasing the initial pressure or reducing the hydraulic diameter can shorten the DDT distance, thereby accelerating the DDT. The simulation shows that methane-oxygen premixed gas explosions can produce an overpressure of 330 MPa, capable of fully fracturing rock cracks.

Key words: shale gas, methane, fractures, explosion, deflagration-to-detonation transition (DDT)

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