Analysis of failure modes and impact resistance factors of PDC cutters

The service life of PDC cutters directly affects the overall drilling performance. In hard and heterogeneous formations, PDC cutters often fail prematurely due to dynamic impacts, leading to short footage and slow penetration rates. Enhancing the dynamic impact resistance of PDC cutters is crucial for achieving one-run drilling and reducing costs. This paper systematically studies the main factors influencing and optimizing the impact resistance of PDC cutters. First, the failure modes of hundreds of returned PDC drill bits were statistically analyzed, revealing that dynamic impact failure, wear failure, thermal damage, and erosion are the primary failure modes. Among these, dynamic impact failure is the most prevalent, with dynamic impact load being the main cause. Following the successful practices of leading international drill bit companies, a set of dynamic impact test and evaluation devices for PDC cutters was designed, and corresponding testing standards were established. Based on this, 19 types of PDC cutters were tested for impact resistance, exploring the effects of cutter diameter, diamond layer thickness, chamfer, cobalt removal, and cutter design on impact resistance. An optimized design methodology to enhance impact resistance was summarized, leading to the proposal of a new arch-axe cutter design. Indoor impact test data verified the superiority of this cutter. The research results indicate that cutter design (non-standard cutters) can significantly improve the dynamic impact resistance of PDC cutters. Additionally, increasing the cutter diameter and chamfer size while reducing the diamond layer thickness also enhances the dynamic impact resistance of PDC cutters. Through the optimization of the arch-ridge design, the independently developed arch-axe cutter improved the dynamic impact resistance by 106.45% and 71.43% compared to flat circular cutters and axe-shaped cutters, respectively.