Novel Wire-Woven Elastic Structure Enabling Reliable and Cost-Effective Adaptive PDC Drill Bits
Authors: Zhao L. , Cheng C. , Ren J. X. , Li C. X. 
Published: April 2024

AbstractShock loading and damage to drill bit cutters caused by changes in rock formations has long been a challenge, especially for shoulder cutters that are subjected to the highest cutting forces. To overcome this problem, a breakthrough solution is emerging—the "Adaptive" polycrystalline diamond compact (PDC) bit, designed with cutters mounted onto a specially engineered elastic structure. This innovation aims to mitigate damaging vibrations, extend bit lifespan, and improve penetration rates in highly heterogeneous formations. However, the development of this elastic structure presents unique requirements—limited size, high force tolerance, low compression set, fast frequency response, and resistance to downhole corrosion and erosion. Current commercial solutions are inadequate, requiring the development of a novel, reliable, and cost-effective elastic material or structure for this purpose-built application.In this study, Finite Element Analysis (FEA) is conducted to determine the necessary properties of the elastic material for achieving optimal adaptive drill bit performance. Based on this criterion, several technical routes, including rubbers, enhanced rubber structures, shape memory Belleville, metal discs, and wire-woven structures, were thoroughly investigated. A significant number of samples, each designed with different material selections and structures, were fabricated and tested to determine the most appropriate solution for this purpose-driven application. This rigorous screening process aims to identify the ideal elastic material or structure that will revolutionize drill bit technology and pave the way for improved drilling efficiency in various rock formations.Throughout the investigation, rubber and enhanced rubber structures proved inadequate due to their limited elastic force and compression set issues. Similarly, shape memory alloys, despite various designs, were unsuitable due to their non-linear elastic properties and poor machinability. Conventional metal discs faced fatigue issues, particularly under high frequency conditions. As a result, wire-woven structures emerged as the most promising candidates after meticulous testing, involving proper raw material selection and an optimized braiding method. In drill bit cutting tests, this novel elastic structure demonstrated exceptional performance compared to traditional designs. It significantly stabilized cutter impact, effectively reducing wear rates by half. This remarkable improvement in drill bit longevity and stability brings a transformative advancement to drilling operations in various rock formations.To the best of our knowledge, this study marks the first successful implementation of the Wire-Woven Elastic Structure in an adaptive drill bit, revolutionizing drilling operations in highly heterogeneous rock formations with improved reliability and cost-effectiveness. This breakthrough also establishes a material-structure-performance relationship for this low-cost elastic material, opening up possibilities for its application in various downhole tools, including drilling, completion, workover, and more.