漏失地层近水平钻孔水力反循环取心试验

基于煤矿井下陷落柱、小断层等地质异常体精确探查对漏失地层近水平孔取心钻进的迫切需要，采用双壁水力反循环连续取心技术进行井下地质异常体探查，分析其技术原理及特点，研制配套的ø89/42 mm双壁取心钻杆和反循环取心钻头，并在某地面矿山进行功能性试验，共施工完成3个近水平取心钻孔，单孔最高取心率为83.6%，最大回次进尺69 m，平均钻进效率为3.61~6.26 m/h。针对漏失地层冲洗液漏失严重的问题，提出双壁取心钻具的结构改进优化方案，采用改进后的取心钻具岩心上返通道返水流量和流速大幅提升，最后指出该套反循环取心施工中出现的钻孔环空排渣及岩心卡堵问题并提出了针对性的解决方案，包括采用正反循环排渣法解决钻孔环空排渣问题和采用中心通道打水解卡方法解决岩心卡堵问题。试验表明：该套双壁取心钻具满足煤矿井下地质异常体探查的施工需要，为煤矿井下地质异常体探查提供新的技术途径。

Test of near-horizontal drilling hydraulic reverse circulation coring in leakage formation

Based on the urgent need of accurate exploration of geological anomalous bodies such as collapse columns and small faults in underground coal mines for near-horizontal boreholes coring drilling of leakage formation, the double-wall hydraulic reverse circulation continuous coring technology was proposed, its technical principle and characteristics were analyzed, the matching ø89/42 mm double-wall coring drilling pipes and reverse circulation coring bits were developed. Three near-horizontal coring boreholes were drilled, the functional tests were carried out in a surface mine, the maximum core recovery rate of a single borehole was 83.6%, the maximum roundtrip footage was 69 m and the average drilling efficiency can be up to 3.61-6.26 m/h. The relevant improvement and optimization schemes of double-wall coring tool were put forward to solve the problem of serious flushing fluid leakage in leakage formation, and subsequent tests have shown that the return water flow and flow rate of the core return channel were greatly improved with adopting optimized coring tools. Finally, the problems of borehole annulus slagging and core blocked in the reverse circulation core construction was pointed out and the corresponding solutions were put forward, including using the method of positive and reverse circulation deslagging to solve the problem of hole annulus deslagging and using the method of hydraulic releasing stuck in the center channel to solve the problem of core stuck. The test shows that the double-wall coring drilling tool can meet the operation requirements of underground geological anomalous bodies exploration and provides a new technical approach for underground geological anomalous bodies exploration.