瓦斯抽采钻孔合理封孔深度关键技术研究

Research on key technologies for reasonable sealing depth of gas extraction drilling

对于单一主采煤层的突出矿井,主要采用抽采钻孔预抽煤层瓦斯的消突措施,抽采钻孔合理的封孔深度是确保高效抽采的关键因素,一旦钻孔封孔深度不够,导致钻孔漏气而封孔失效,将严重影响整个抽采系统的工作效率和煤矿安全生产。针对这一问题,采用声波法进行岩巷松动圈现场测试,并利用FLAC^(3D)数值模拟岩巷应力“三带”发育范围;采用钻屑法进行煤巷松动圈现场测试,对煤巷应力“三带”发育范围进行考察;在进行钻孔始封深度的理论分析的基础上,现场开展钻孔封孔的始封深度优化试验。研究表明,声波法测定岩巷松动圈范围为4.4~4.7 m,与FLAC^(3D)数值模拟结果4.2 m基本吻合;根据钻屑量指标在煤巷应力“三带”测定值的变化规律,现场测定煤巷卸压带范围为距孔口10 m;根据巷道应力“三带”分布,确定穿层钻孔与顺层钻孔的合理始封深度,并进行现场实验考察,将始封深度避开卸压带,抽采效果均有大幅度提高。

For the outburst mine of a single main coal seam,the outburst measures of pre-pumping coal seam gas are mainly used in the extraction drilling,and the reasonable sealing depth of the pumping drilling is the key factor to ensure efficient pumping,once the drilling sealing depth is not enough,resulting in the drilling leakage and the sealing hole fails,which will seriously affect the work efficiency of the entire extraction system and the safety production of coal mine.Regarding this issue,the acoustic wave method was used to test the loose zone of the rock roadway,and the development range of the"three zones"of stress in the rock roadway was simulated by FLAC^(3D)numerical method;the field test of the loose circle of the coal roadway was carried out by the drill cuttings method,and the development range of the"three zones"of stress in the coal roadway was investigated;on the basis of theoretical analysis of the initial sealing depth of drilling,on-site optimization experiments on the initial sealing depth of drilling were carried out.Research shows the range of the loose zone of the rock roadway measured by the acoustic wave method was 4.4-4.7 m,which was basically consistent with the FLAC^(3D)numerical simulation result of 4.2 m;according to the variation law of the measured values of the"three zones"of stress in the coal roadway based on the drill cuttings index,the range of the pressure relief zone of the coal roadway was determined to be 10 m from the orifice.Based on the stress distribution of the"three zones"in the roadway,the reasonable initial sealing depth for cross layer drilling and parallel layer drilling was determined,and on-site experimental investigation was carried out.The initial sealing depth was avoided from the pressure relief zone,and the pumping effect was greatly improved.