Development and Verification of Triple-Ridge-Shaped Cutter for PDC Bits

Abstract

Summary Polycrystalline diamond compact (PDC) cutter is the key component of PDC bits, whose rock-breaking characteristics are particularly crucial for the bit performance. Based on the understanding on rock-breaking characteristics of various shaped cutters, the multiridge-shaped cutter has been developed to improve the cutting efficiency and durability of PDC cutters. The design of multiple ridges combines the advantages of both the shaped cutter and the reasonable narrow cutter spacing of the bit cutting structure. More specifically, a triple-ridge-shaped cutter (TSC) was compared with the widely used axe-shaped cutter (ASC) in this work to recognize the superiority of the novel multiridge cutter shape. Numerical simulation, laboratory experiments, and field testing were performed to investigate the cutter-rock interactions of TSC and ASC. Numerical simulations were carried out using nonlinear finite element software LS-DYNA and verified by the single cutter testing. Both numerical and experimental results proved that the stress concentration caused by the triple-ridge cutter shape of TSC is significantly greater than that of ASC during the cutter-rock interaction. And the tangential force of TSC is much less than that of ASC under the same cutting conditions, indicating that the PDC bit equipped with TSCs requires less torque while drilling. According to the results of the fractal analysis model of cuttings and the mechanical specific energy (MSE), TSC consumed less drilling energy than ASC to break the same volume of rock, which demonstrated that the TSC has greater cutting efficiency than ASC. Beneficially, the greater cutting aggressivity of TSC in turn improves the wear resistance. The laboratory wear and impact tests presented that TSC outperforms ASC in both wear resistance and impact resistance, indicating better durability under downhole. Although only one controlled experiment was conducted in the field, the field test result showed over 100% improvement in average rate of penetration. In short, the numerical, laboratory, and field testing have confirmed a great potential of TSC in improving the cutting efficiency and durability of PDC bits. The results of this work will provide valuable guidance for the development of shaped PDC cutters to overcome engineering limitations.