Experimental Study on Working Mechanism of Roller PDC Bit

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.