煤层瓦斯抽采钻孔密封理论模型与工程技术研究

Research on the theoretical model and engineering technology of the coal seam gas drainage hole sealing

瓦斯抽采浓度低是由孔内漏气和孔边裂隙漏气共同导致的,为分析钻孔漏气机理,基于多物理场耦合理论建立了考虑孔内漏气和孔边裂隙漏气的数学模型.采用COMSOL Multiphysics对其进行数值求解,结果表明采动影响区漏气裂隙的宽度越大,钻孔瓦斯抽采浓度衰减得越快,漏气裂隙特性是影响瓦斯抽采浓度的重要因素.为了保障封孔质量、增强瓦斯抽采效果,现代钻孔密封技术不仅要实现孔内密封,更要有效封堵钻孔周边煤岩体漏气裂隙,重点介绍了囊袋注浆封孔和二次封孔2种封堵裂隙的新技术及应用效果.

Low gas drainage concentration was caused by the leak in the borehole and the leak- age fracture around the borehole. Based on the multi-physics field coupling theory, the mathe- matical model considering the leak in the borehole and the leakage fracture around the borehole was established for analyzing borehole leakage mechanism. The model was solved by COMSOL Multiphysics software. The results show that the bigger the width of the leakage fracture in the mining area is, the faster the decay rate of the gas drainage concentration is. The leakage fracture characteristic is an important factor to influence the concentration of gas drainage. In order to ensure sealing quality and improve the gas drainage results, the modern hole sealing technology not only needs to achieve the sealing in the borehole, but also seal the the leakage fracture field of coal mass around the borehole. Accordingly, two new fracture sealing technol- ogies, namely bag-type grouting hole sealing and secondary hole sealing, were introduced em- phatically in this paper with their application effects.