顺层钻孔瓦斯抽采半径及布孔间距试验研究

Experimental study on both gas drainage radius and bedding borehole space

为准确测定瓦斯有效抽采半径,确定合理的顺层钻孔布置间距,提出采用测定钻孔周围煤体特定时刻的瓦斯含量的方法。对蒋家河煤矿4号煤层有效抽采半径及钻孔间距进行试验研究。通过监测钻孔抽采流量,并根据采掘计划、钻孔施工情况,来预算工作面钻孔的最短抽采时间和平均抽采时间。试验结果表明,当抽采流量衰减到稳定值及钻孔抽采时间达到预先算得的最短抽采时间、平均抽采时间时,单孔有效抽采半径分别为3.5,4和4.5 m;通过对比3个时刻2钻孔中心位置与钻孔另一侧等距离位置的瓦斯含量,确定3个时刻的钻孔间距比2倍的单孔有效抽采半径分别增加了1.1-2.2,0.8-1.6和0.6-1.2 m,并且相邻2钻孔叠加的效果取决于抽采时间和钻孔间取样点距两侧抽采孔的距离是否小于钻孔的有效抽采半径。

A method was worked out for determing the radius gas extraction effective radius and determining the rational bedding borehole space.On the basis of measuring the gas content of the coal around the borehole at a specific time. Experimental researches were carried out on the radius and the space for the Jiangjiahe coal mine 4th coal seam. Through the results, it was found that when borehole drainage flow rate reduces to theequilibrium value and borehole drainage time reachs the shortest gas drainage time and average gas drainage time, the effective extraction radius of the coal seamare 3.5, 4and 4.5 m respectively.