Study on Mechanical Properties and Rock Breaking Effect of Ridge-Shaped Cutters

Based on the formation characteristics, the targeted selection of shaped cutters can reduce the probability of PDC cutters failure and increase the rate of penetration (ROP) and footage. In order to comprehensively compare the mechanical properties and rock-breaking effect of ridge-shaped PDC cutters, three kinds of ridge-shaped PDC cutters (165-axe, 135-axe, and triple-edged) were firstly studied for wear resistance and impact resistance, and then granite was selected to conduct single-cutter cutting experiments at three depths of cut (DOC), and simulated drilling experiments of full-size bits under different weight of bit, and compared with round cutter. The results show that: ① The wear resistance of ridge-shaped PDC cutter is better than that of round cutter. ② The impact resistance of 165-axe and three-edged cutter is better than that of round cutter, and 135-axe has poorer impact resistance due to the lack of support at the point of impact. ③ At the same DOC, the tangential force and normal force of ridge cutter are lower than that of round cutter, and the smaller the angle of the ridge is, the smaller the cutting force is. ④ The 135 axe shape has the fastest ROP and is suitable for high WOB, the triple-edged cutter have a faster ROP in the low drilling pressure range (less than 20 kN) and a slower ROP in the high drilling pressure range (more than 20 kN) compared to the 165-axe. The rounded cutter have the slowest ROP and are suitable for lower WOB. The experimental results show that when the ridge angle changes, the support material at the impact point also changes, which affects its impact resistance, and at the same time, the change of the ridge angle will change the stress concentration inside the rock in front of it, which will change the effect of rock breaking. The results of this paper can provide a reference for the optimal design of ridge cutter design, bit cutter placement and drilling parameter selection.