下沟煤矿本煤层预抽钻孔合理封孔长度研究

Study on Reasonable Sealing Length of Pre-drilled Hole in the Coal Seam of Xiagou Coal Mine

封孔长度的合理性对于煤层预抽钻孔的抽采质量影响较大,当封孔长度较大时,不利于封孔段瓦斯的抽采,同时封孔成本增加,反之当封孔段长度较小时,若未封孔部分与煤壁裂隙导通,钻孔发生漏气又影响钻孔抽采质量。为确定合理的封孔长度,针对下沟煤矿302工作面特定的地质条件,采用单孔声波发射对巷道卸压区和应力集中区范围进行了研究,通过分析卸压区范围,确定了合理的封孔长度,并结合试验孔周边的预抽钻孔抽采数据,进行了验证分析,得出该工作面的合理封孔深度为8 m。

The rationality of the length of hole sealing for the seam drainage borehole in the extraction of a greater influence on the quality,when the hole sealing length is bigger,does not favor the hole sealing section of the gas extraction,and hole sealing cost increases,whereas when the hole sealing length is small,without hole sealing part and the coal wall fracture conductivity,borehole leakage and affect the quality of borehole extraction.In order to determine a reasonable length of hole sealing,in view of the ditch coal mine 302 working face under the specific geological condition,the single-hole acoustic emission on the pressure relief area and the stress,high range are studied,through the analysis of unloading zone,the reasonable hole sealing length,and combining the test hole drainage borehole surrounding extraction data,verified analysis,it is concluded that the reasonable hole sealing depth of the working face is 8 m.