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煤层透气性系数测定方法研究进展

Research progress on methods for determining the permeability coefficient of coal seams

  • 摘要: 煤层透气性系数是评价瓦斯抽采难易程度、保护层卸压增透效果、煤与瓦斯突出危险性大小的重要指标。简要回顾了煤层透气性系数测定方法的发展历程,重点讨论了实验室法、径向流量法、瓦斯压力恢复曲线法及注气法的研究进展及各自特点。分析结果表明:实验室法具有操作简单、成本低等优点,但难以构建与井下完全一致的模拟环境,未来可作为现场测定的重要辅助手段;径向流量法虽在现场应用比较广泛,但存在计算步骤繁琐、取值不连续等问题,诸多学者虽提出多种优化策略,却尚未建立统一计算标准;瓦斯压力恢复曲线法具有原位测试性强、数据解析直观等特点,但受封孔质量和测压精度影响较大,难以准确拾取中期径向流斜率段;注气法在复杂渗流煤层中展现出良好潜力,为各向异性透气性测定提供可行思路,但现场测定过程复杂,现场测试精度与数据稳定性受限。未来煤层透气性系数测定方法应重点从构建多场耦合与多尺度统一的理论模型、统一径向流量法行业标准与计算规范、提升压力恢复曲线识别与分析精度、优化注气介质选择与测点布局、提升现场监测精度与自动化水平等几个方面深化研究。

     

    Abstract: The permeability coefficient of coal seams serves as a crucial indicator for evaluating the difficulty of gas extraction, the effectiveness of pressure relief in protective layers to enhance permeability, and the severity of coal and gas outburst hazards. This paper briefly reviews the development of coal seam permeability coefficient determination methods, focusing on the research progress and respective characteristics of laboratory methods, radial flow methods, gas pressure recovery curve methods, and gas injection methods. Analysis indicates that laboratory methods offer advantages such as simplicity and low cost, but struggle to replicate underground conditions perfectly; they may serve as important supplementary tools for field measurements in the future. The radial flow method, though widely applied in the field, suffers from cumbersome calculation steps and discontinuous data values. Despite various optimization strategies proposed by scholars, no unified calculation standard has been established. The gas pressure recovery curve method offers strong in-situ testing capabilities and intuitive data interpretation, but it is significantly affected by plugging quality and pressure measurement accuracy, making it difficult to accurately capture the mid-term radial flow slope segment. The gas injection method demonstrates promising potential in complex seepage coal seams, offering a viable approach for anisotropic permeability determination. However, its field measurement process is complex, and its on-site testing accuracy and data stability are limited. Future research on coal seam permeability coefficient determination should focus on several key areas: developing unified theoretical models that integrate multi-field coupling and multi-scale analysis; establishing industry standards and computational specifications for the radial flow method; enhancing the accuracy of pressure recovery curve identification and analysis; optimizing gas injection medium selection and test point layout; and improving field monitoring precision and automation levels.

     

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