Innovative Dual-Chamfer Edge Technology Leads to Performance Gains in PDC Bits

Abstract

Abstract The dual-chamfer diamond cutter is a new technology combining a primary chamfer with a secondary edge, enabling greater footage to be drilled without compromising rate of penetration (ROP). The average distance drilled in the Mississippi Lime formation was increased by 40% while maintaining comparable ROP to offsets and with significantly improved dull bit conditions, resulting in greater reliability. Since 2013, more than 1, 500 runs with bits utilizing dual-chamfer technology were performed in Oklahoma. The dull state was significantly improved, resulting in reduced incidence of ring outs, core outs and other deleterious bit damage. The data presented in this paper are based on over 130 laboratory drilling tests. Chip flow analysis was conducted using a unique visual pressurized single-cutter test machine. Full-bit testing was carried out in a pressurized drilling simulator to compare drilling performance. Cutter wear life testing was conducted using an aggressive granite wear test protocol where a 100 to 200% increase in cutter life was documented by edge geometry changes. Chamfering polycrystalline diamond compact (PDC) cutters has a significant positive effect on edge durability and overall longevity. This concept has not changed over several decades since the introduction of chamfered PDC cutters. Many investigations were conducted with either a singular change to the chamfer height or chamfer angle or with combined edge geometries. These investigations, however, showed only limited success. The new geometry is based on a thorough understanding of historic investigations and failures observed on how diamond cutter wear flats are formed and degrade. Developments in the drilling sector with greater use of high-power directional motors results in more intermittent off-center drilling with high cutter edge loading. In addition, cutter developments now use leaching methods to reduce cutter wear and better control thermal cyclic loading. A leached diamond layer makes diamond cutters more susceptible to impact damage, resulting in greater premature and catastrophic failures. For the customer, the improved cutter technology resulted in significant cost savings and more confidence in tool life, enabling greater endurance and durability. Ultimately, the new cutter technology enables lower drilling costs and opens more drilling frontiers that were previously unprofitable.