Numerical Simulation and Field Testing on Rock Breaking of Prismatic PDC Cutters

When drilling in hard and abrasive formations, conventional PDC bits with planar cutters have low ROP and short lifespans. In order to solve the above problems, domestic and foreign research institutions have developed a variety of PDC bits embedded with non-planar cutters. In this paper, the rock breaking characteristics of non-planar prismatic PDC cutters and planar PDC cutters and the rock breaking ability of PDC bits embedded with such two kinds of cutters are compared by numerical simulation and field test. When analyzing the stress distribution, it is found that planar PDC cutters break rocks mainly through shearing and extrusion. And the prismatic PDC cutters can superimpose the hitting and splitting of ridges and the shearing and extrusion of lateral surfaces to break rocks, which has a higher rock breaking efficiency. At the same cutting depth, the fluctuation of tangential forces for prismatic PDC cutters is smaller than that of planar PDC cutters, and the average tangential and axial forces are also lower, which is beneficial to improving the lifespans of PDC bits. Results of field tests show that when drilling in the Xujiahe Formation in adjacent Wells, the average ROP and average footage of the prismatic PDC bits are 55% and 5.68% higher than that of the planar PDC bits, respectively. This paper can provide theoretical and practical supports for the application of PDC bits with prismatic cutters.