王家岭煤矿高位定向长钻孔抽采顶板卸压瓦斯技术

Technology of pressure-relief gas drainage by highly oriented level boreholes from roof fracture zone in Wangjialing coal mine

王家岭煤矿是典型的低瓦斯煤层高强度开采引起的高瓦斯矿井,由于煤层瓦斯含量不高且透气性差,所以瓦斯抽采顶板难度大。为了得到适合于王家岭煤矿的高位定向水平钻孔抽采卸压瓦斯工艺参数,现场跟踪考察了12318综放工作面高位定向钻孔的瓦斯抽采体积分数、纯流量等工艺参数,分析了布孔垂直层距、水平错距等关键参数与抽采效果的关联特性。依据实测的顶板岩层力学参数及经验公式,计算得到顶板冒落带高度,为19.11~24.10 m;裂隙带高度,为57.06~74.86 m。分析抽采效果认为:同一钻场中的钻孔抽采瓦斯纯流量随着钻孔垂直层距的增大而增大,钻孔抽采瓦斯纯量随水平错距的减小而增大,垂直层距最大的2个钻孔瓦斯抽采纯量占钻场抽采总量的70%以上。钻场钻孔垂直层距在25~41 m时,对工作面上隅角瓦斯防治效果明显优于垂直层距20 m的钻场。

Wangjialing coal mine is a typically high gas coal mine caused by high strength mining in low gas coal seam,and it is difficult to drain gas from the coal seam due to the poor gas content and permeability of coal seam. In order to study the technical parameters of highly oriented level boreholes suitable for pressure-relief gas drainage in Wangjialing mine,the gas drainage process parameters such as gas concentration,pure gas flow rate and so on were investigated in fully mechanized top coal caving face 12318,and the relationship between key parameters such as level location on vertical,horizon offset distance from return airway and drainage effect were analyzed. Based on coal seam roof mechanical parameters,the heights of roof caved zone and fractured zone were calculated by empirical formula,whose ranges were 19. 11 ~ 24. 10 m and 57. 06 ~ 74. 86 m respectively. The analysis of drainage effect showed that drainage pure gas flow value of the borehole increased with the increase of drilling horizon in the same drill site,while the value increased with the decreasing of the horizon offset distance from return airway; the drainage pure gas flow value from the highest tow borehole was more than 70% of the total of the drill site. When boreholes vertical height range was 25 ~ 41 m,gas drainage effect for reduce gas concentration of top corner was significantly better than those boreholes of horizon height less than 20 m.