<p>Scientific Understanding of Overlying Strata Fracture Development and Distribution Characteristics of High-Permeability Zones for Pressure-Relieved Gas: A Key Approach to Optimizing Gas Drainage Location Selection. Taking the 26 Middle 06 working face in Lvtang Coal Mine as a case study, this research investigates the evolution of mining-induced fractures and high-permeability zones through physical similarity simulation and field borehole observation, leading to optimized parameters for gas drainage borehole layout. The results indicated that as the working face advanced, the periodic weighting interval ranged from 8 to 13 m, with the heights of the caved zone and fractured zone determined to be 11.7 m and 33.9 m, respectively. The distribution pattern of fractal dimension under different periodic weighting conditions was analyzed, revealing that the fractal dimension increases with the occurrence of periodic weighting and decreases with increasing height from the coal seam floor. A fractal dimension threshold of 1.2 was utilized to delineate the overlying strata fracture field into high-permeability zones for pressure-relieved gas and compacted zones. The final development height and width of the high-permeability zone were identified as 43.2 m and 21.9 m, respectively. The evolutionary process of the high-permeability zone was observed to undergo four distinct stages: "integrated region, initial emergence, cross fusion, and regional separation." A quantitative characterization equation for the high-permeability zone, based on fractal dimension, was established. Field borehole observations yielded a caved zone height of approximately 12.75 m and a fractured zone height ranging from 30.8 m to 34.2 m. Based on the experimental and observational results, borehole layout parameters were optimized and validated in the field. The optimized scheme resulted in a 30% increase in pure gas drainage volume, and the average daily power generation from gas rose from 56,605.22 kWh to 71,187.34 kWh.</p>

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Evolution of fractal dimension and efficient extraction of gas in high-permeability zones under mining-induced pressure relief at Lvtang coal mine

  • Chao Wang,
  • Ze-chen Chang,
  • Lei Li,
  • Peng-xiang Zhao,
  • Zhu-chun Wang,
  • Xu Guo,
  • Jian-kai Dong

摘要

Scientific Understanding of Overlying Strata Fracture Development and Distribution Characteristics of High-Permeability Zones for Pressure-Relieved Gas: A Key Approach to Optimizing Gas Drainage Location Selection. Taking the 26 Middle 06 working face in Lvtang Coal Mine as a case study, this research investigates the evolution of mining-induced fractures and high-permeability zones through physical similarity simulation and field borehole observation, leading to optimized parameters for gas drainage borehole layout. The results indicated that as the working face advanced, the periodic weighting interval ranged from 8 to 13 m, with the heights of the caved zone and fractured zone determined to be 11.7 m and 33.9 m, respectively. The distribution pattern of fractal dimension under different periodic weighting conditions was analyzed, revealing that the fractal dimension increases with the occurrence of periodic weighting and decreases with increasing height from the coal seam floor. A fractal dimension threshold of 1.2 was utilized to delineate the overlying strata fracture field into high-permeability zones for pressure-relieved gas and compacted zones. The final development height and width of the high-permeability zone were identified as 43.2 m and 21.9 m, respectively. The evolutionary process of the high-permeability zone was observed to undergo four distinct stages: "integrated region, initial emergence, cross fusion, and regional separation." A quantitative characterization equation for the high-permeability zone, based on fractal dimension, was established. Field borehole observations yielded a caved zone height of approximately 12.75 m and a fractured zone height ranging from 30.8 m to 34.2 m. Based on the experimental and observational results, borehole layout parameters were optimized and validated in the field. The optimized scheme resulted in a 30% increase in pure gas drainage volume, and the average daily power generation from gas rose from 56,605.22 kWh to 71,187.34 kWh.