反循环取样技术在钻屑瓦斯解吸指标K1值测定中的应用

摘要

针对传统的麻花钻杆机械排渣取样测定K1值存在受孔壁残粉影响较大、煤样暴露时间无法准确界定的弊端,研究了双壁钻杆的反循环取样技术用于煤矿井下K1值的深孔预测,该技术可将孔底钻屑通过钻杆中心管输送至孔口实现快速、定点取样,避免了传统取样方式存在的有效深度浅、深孔预测可靠性低等问题.现场试验结果表明:反循环取样技术应用于乌兰煤矿K1值测定的有效预测深度可提高至30m,且不受钻孔倾角的影响.%As the traditional method of K1 determination using twist drill pipe mechanical sampling is greatly influenced by the residual powder of the hole wall and the coal samples exposure time can't be accurately defined,reverse circulation sampling technique based on double-wall drill pipe is proposed for the determination of K1 value for underground coal mine.This technique can transport the hole drilling cuttings at the bottom to the drilling external,so as to achieve rapid and fixed-point sampling,and avoid the problems existing in the traditional sampling method,such as small effective borehole depth and poor reliability for prediction of deep hole.K1 value determination test using reverse circulation sampling technique in Wulan Coal Mine showed that,the effective prediction depth of K1 value was up to 30m,and the result was not affected by borehole inclination.