煤层钻孔瓦斯抽放与漏气耦合模型建立及现场应用研究

Modeling and Field Application of Coupled Coal Seam Borehole Gas Drainage and Air Leakage

煤层钻孔周围漏气导致抽采瓦斯质量差,瓦斯突出危险难以消除,还可能引起煤炭自燃、瓦斯爆炸等灾害。建立了基于基质收缩和有效应力对煤层渗透性影响的双介质耦合模型,对影响瓦斯抽采质量的关键因素进行了研究,瓦斯浓度随密封长度和钻孔直径的增大而升高,随抽采负压和煤层渗透率的增大而降低。因此,研发了新型钻孔密封技术,可以完全密封钻孔周围的各种裂缝,现场试验表明,改进后的密封技术瓦斯浓度是传统密封方法的1.91倍,且在后续的抽采阶段仍保持较高的抽采水平,应用效果较好。

Air leakage around coal seam drill holes leads to poor quality of gas extraction,and the danger of gas protrusion is difficult to be eliminated,and it may also cause spontaneous coal combustion,gas explosion and other disasters.A two-media coupling model based on the effects of matrix shrinkage and effective stress on the permeability of coal seams was established,and the key factors affecting the quality of gas extraction were investigated.The gas concentration increases with the increase of sealing length and drilling diameter,and decreases with the increase of negative pressure of extraction and permeability of coal seams.Therefore,a new type of drilling sealing technology was developed,which can completely seal all kinds of cracks around the drilling hole.Field tests show that the gas concentration of the improved sealing technology is 1.91 times higher than that of the traditional sealing method,and it still maintains a higher level of extraction in the subsequent extraction stage,which has a better application effect.