滚轮式PDC钻头工作机理的试验研究

Experimental Study on Working Mechanism of Roller PDC Bit

针对页岩气钻采中定向钻进的PDC钻头扭矩波动大、冲击振动大、工具面不稳定等问题,笔者提出一种刀翼上设置有双侧支撑的滚轮新结构钻头,通过滚轮单元破岩实验以及全钻头钻进破岩实验来开展新型钻头减扭、缓冲机理研究,主要研究6种滚轮轮廓形状、4种滚轮的吃入深度、6种滚轮径向位置、7种PDC齿相对高度等因素对新型钻头扭矩、钻压的影响规律。结果表明:6种轮廓滚轮的等效摩擦系数均低于PDC齿,且为PDC齿的18.65%~43.73%,得出滚轮减扭能力高于PDC齿;6种不同径向位置的滚轮缓冲能力均强于PDC齿,为PDC齿的1.59~9.17倍,滚轮式PDC钻头的扭矩为常规PDC钻头的71.72%~98.33%;随着滚轮与PDC齿相对高度的减小,钻头扭矩逐渐减小,滚轮钻压的占比也逐渐增加,钻头减扭能力、缓冲能力均增加,为适用于页岩气钻采的新型钻头产品设计与研制提供理论支撑。

In view of the problems such as large torque fluctuation,large impact vibration and unstable tool surface of PDC bits for directional drilling in shale gas drilling and production,the author proposes a new roller structure bit with bilateral supports on the blade.Through rock breaking experiment of roller unit and rock breaking experiment of full bit drilling,the mechanism of new bit torque reduction and buffering is studied,mainly including 6 roller profile shapes,4 roller pressing depths,6 roller radial positions The influence of the relative height of 7 kinds of PDC teeth on the torque and WOB of the new drill bit.The results show that the equivalent friction coefficients of the six contour rollers are lower than those of the PDC teeth,and are 18.65%~43.73%of the PDC teeth;The buffering capacity of roller at six different radial positions is stronger than that of PDC teeth,which is 1.59~9.17 times of that of PDC teeth.The torque of roller PDC bits is 71.72%~98.33%of that of conventional PDC bits;With the reduction of the relative height of the roller and PDC teeth,the bit torque gradually decreases,the proportion of the roller weight on bit also gradually increases,and the bit torque reduction capacity and buffering capacity increase,providing theoretical support for the design and development of new bit products suitable for shale gas drilling and production.