顺层钻孔预抽瓦斯技术是降低煤层瓦斯含量的有效方法之一,合理的布孔参数是提高煤层瓦斯预抽效果的关键｡为提高顺层钻孔布孔精准性和科学性,建立了含瓦斯煤体流固耦合抽采模型,基于响应面法设计布孔参数优化方案,运用COMSOL Multiphysics 模拟软件分析了地质因素(煤层瓦斯含量､透气性系数)和工程因素(抽采负压､钻孔直径､布孔间距)交互作用对钻孔预抽煤层瓦斯的影响规律,提出钻孔间最大瓦斯压力与达标压力比(Pmax/Pb)的布孔参数判定指标,创新了煤层“分时分区”式顺层钻孔预抽煤层瓦斯精准布孔方法,得到适用于不同煤层瓦斯赋存特征的最优钻孔布置参数,并进行现场试验｡结果表明:预抽初期,相邻钻孔间抽采叠加效应不明显;随着预抽时间延长,抽采叠加效应越发显著,垂直钻孔方向的抽采达标区域逐渐由孤立向复合转变｡不同预抽时间下,Pmax/Pb对各因素的敏感性依次为:布孔间距>煤层瓦斯含量>透气性系数>钻孔直径>抽采负压｡不同预抽时间下,煤层瓦斯含量和透气性系数的交互作用响应等值线分布密集,2者对Pmax/Pb影响非常显著,并且对Pmax/Pb数值影响较大;工程因素中抽采负压与钻孔直径的交互作用响应等值线呈圆形分布,说明二者交互作用不明显;在布孔间距与地质因素交互作用下,响应等值线沿布孔间距方向更为密集,布孔间距对Pmax/Pb影响仍然是显著的,与单因素分析结果相互佐证｡试验工作面采用“分时分区”式顺层钻孔精准布孔方法确定的合理布孔参数依次为:抽采负压24.0 kPa､钻孔直径113 mm､布孔间距6.0 m;经优化预抽钻孔参数后,现场瓦斯预抽效果良好且预抽达标检验合格,实现了煤层瓦斯精准预抽｡

One of the most effective methods to reduce the gas content of coal seam is to pre⁃drain gas by drilling a⁃long the seam. Rational borehole layout parameters are the key to improve the effectiveness of coal seam gaspre⁃drainage. In order to improve the accuracy and scientificity of borehole layout in seam drilling,a fluid⁃solid cou⁃pling model of gas⁃containing coal was established. Based on the response surface method,an optimization scheme ofborehole arrangement parameters was designed. The COMSOL Multi⁃physics simulation software was used to ana⁃lyze the influence of the interaction between geological factors (coal seam gas content,gas permeability coefficient)and engineering factors (drainage negative pressure,borehole diameter,borehole spacing) on the pre⁃drainage of coalseam gas by drilling. The determination index of the ratio of the maximum gas pressure between boreholes to the stand⁃ard pressure (Pmax / Pb ) was proposed. The precise distribution method for pre⁃draining coal seam gas by “time⁃sharing partition” type of boreholes was developed. The optimal borehole layout parameters suitable for different coalseam gas occurrence characteristics were obtained. Finally,the field test of gas pre⁃drainage was carried out. The re⁃sults show that the superimposition effect of drainage between adjacent boreholes was not obvious at the initial stage ofpre⁃drainage. As the pre⁃drainage time was extended,the superimposing effect of draining became more and more sig⁃nificant,and the drainage standard area in the vertical borehole direction gradually changed from isolated to composite.Under different pre⁃draining times,the sensitivity of Pmax / Pb to various factors was as follows:borehole spacing > coalseam gas content > gas permeability coefficient > borehole diameter > drainage negative pressure. The interaction re⁃sponse contours of coal seam gas content and permeability coefficient were densely distributed,which indicated thatboth have a very significant effect on Pmax / Pb and greater impact on the value of Pmax / Pb. Among the engineering fac⁃tors,the interaction response contours of negative pressure and borehole diameter were distributed in a circular shape,indicating that the interaction between the two was not obvious. Under the interaction of borehole spacing and geolog⁃ical factors,the response contours were denser in the borehole spacing direction,and the effect of borehole spacing onPmax / Pb was still obvious,which was mutually corroborated by the results of single factor analysis. The reasonable bore⁃hole layout parameters determined by the time⁃sharing district type of accurate borehole layout method in the test work⁃face were as follows:drainage negative pressure was 24.0 kPa,borehole diameter was 113 mm,and borehole spacingwas 6.0 m. After optimizing the parameters of pre⁃drainage borehole,the on⁃site gas pre⁃drainage effect was goodand the pre⁃drainage compliance test was qualified,which realized the accurate pre⁃drainage of coal seam gas.