煤矿井下水力反循环连续取芯用PDC钻头设计与应用

Design of PDC bit for hydraulic reverse circulation continuous coring in underground coal mine

为提高煤矿井下水力反循环连续取芯钻进施工效率,结合其取芯原理,采用流体力学原理对钻头水路进行设计,使反循环过程中岩心顺利运移,同时保证孔底岩粉顺利排出。通过流场分析,验证了钻头水力参数的合理性;对卡断器与岩心相互作用进行力学分析,优选了卡断器结构参数,保证岩心顺利卡断;采用刀翼式圆弧形钻头切削结构,提高钻头切削效率。现场试验表明,该取芯钻头能够满足岩心运移要求,综合岩心采取率达到78%,岩层段钻进效率可达7.5~9 m/h,煤层段钻进效率达到9~18 m/h,满足了水力反循环连续取芯高钻进效率、钻进中连续取芯、纯钻时间长、“实时”取样等要求。本研究拓宽了水力反循环连续取芯工艺的应用范围,为煤矿井下相关取芯钻孔施工提供了钻头方案。

In order to improve the construction efficiency of hydraulic reverse circulation continuous core drilling in underground coal mine,combining with its technological principle,through the design of hydraulic parameters of drill bit,the principle of fluid mechanics is used to allocate the water of drill bit reasonably,which not only ensures the smooth migration of core,but also ensures the smooth discharge of rock powder.The hydraulic parameters of the design are verified by flow field analysis to ensure the rationality of hydraulic parameters.Through the mechanical analysis of the interaction between the clipper and the core,the structural parameters of the clipper are optimized to ensure that the core can be successfully clipped.The cutting structure of the bit is designed,and the blade type circular arc cutter structure is used to ensure that the bit has higher cutting efficiency.Field tests are carried out with the designed drill bit,and the result shows that the hydraulic reverse circulation continuous coring bit can meet the flow distribution requirements of cooling drill bit and carrying core,and the comprehensive core taking rate reaches 78%.The drilling efficiency of rock section can reach 7.5~9 m/h,and that of coal section can reach 9~18 m/h.It meets the requirements of high drilling efficiency,continuous coring during drilling,long pure drilling time and real-time sampling.This study broadens the application scope of hydraulic reverse circulation continuous coring technology,and provides a drill bit scheme for coring drilling construction in underground coal mine.