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.

The Brazil ultra-deepwater, pre-salt application has been a very challenging drilling environment since exploration activity began in 2005. The initial pre-salt section contains limestone with random silicified nodules. Over the last few years, operators have collected large amounts of data for service companies to analyze to improve drilling performance through bit design. Using this information, a hybrid bit design with the most advanced cutter and bit technology was developed successfully increasing the distance drilled by 138% and the rate of penetration (ROP) by 171%.Prior to advanced hybrid bit technology, a variety of other drill bit technologies such as polycrystalline diamond compact (PDC) bits and impregnated designs were used in the pre-salt. Historically, impregnated bits had longer runs, but with high mechanical specific energy (MSE) and low ROP, drilling with these bits was not economical. Contrarily, PDC bits can deliver higher ROP but cannot drill as far as impregnated bits. Three hybrid designs, the last one using dual-chamfer technology, were brought into this application to reduce cost-per-meter through better drilling efficiency and ROP. Each successive design managed to exceed customer expectations.Extensive laboratory tests were conducted on the hybrid designs to address the demanding needs of pre-salt applications. These unique bits showed promising results on atmospheric surface rig tests and in pressurized bottomhole simulator testing. Hybrid bits produced much less torque, with smoother torque fluctuations and faster ROPs than roller-cone and PDC bits through the simulated interbedded formations in laboratory testing. Novel dual-chamfer cutters used in the bit have been lab tested on a vertical turret lathe (VTL), a visual pressurized single-point-cutter (VSPC) test machine and a monotonic loading test. Cutter testing showed positive VTL results and increased resistance to diamond fractures.Ultra-deepwater drilling is very demanding and expensive, so operators want to achieve total depth in just one run by avoiding trips to change out the bit or bottomhole assembly (BHA). The improved bit and cutter technology resulted in significant cost savings and confidence for the customer. The performance of the hybrid bit with dual-chamfer cutters was significantly better than offsets, saving the operator approximately USD 9769/m.

The development of improved synthesis techniques for polycrystalline diamond compacts (PDC) positively impacted fixed cutter drill bit performance. Coupled with these advances, recent developments in cutter geometry show improved cutter performance in many applications. Laboratory and field testing has demonstrated that modifying the face geometry of the PDC cutter used in a fixed cutter bit is one of the most direct ways to affect the efficiency and longevity of the bit's cutting structure. This paper describes a new non-planar cutter face geometry that has increased footage drilled, rate of penetration (ROP), and improved the bit dull condition in the Meramec formation in western Oklahoma's STACK play. A drilling mechanics focused team created a finite element analysis (FEA) model of the rock cutting process to optimize cutter face geometry for improved cutting efficiency. The new non-planar geometry enabled better cutting efficiency and improved cutter cooling. Multiple lab tests were then used to verify the model's predictions. Results from single cutter lab tests showed an 11% increase in cutting distance as measured in a vertical turret lathe test, a 30% decrease in cutting edge temperature from a pressurized cutting test, and a 10% increase in load capacity compared to a previous non-planar geometry in a face load test. Full-scale pressurized drilling tests in the lab showed that a PDC bit with the new geometry was 15% less aggressive with equivalent-to-lower mechanical specific energy (MSE) when compared to the same PDC bit with a previous generation non-planar cutter. Field tests were conducted with the new non-planar geometry applied to a commercial 0.529 inch [13mm] cutter on a standard 8-1/2 in. drill bit design used in the Meramec Lateral application. The paper reviews in detail three test cases in this multiple bit lateral section using the same bit design with and without the new non-planar cutters. In two test wells, we saw direct improvement of 185% distance drilled on average and an18.3% boost in ROP. At least 17 bit runs have been completed in this application using the new non-planar feature, proving it to be a beneficial enhancement. Similar performance improvement has been observed in other applications as well. The optimized cutter geometry has led to further and faster runs, resulting in significant time savings and improved consistency. The use of advanced cutter geometries provides a significant boost in drilling performance beyond that normally achieved through fixed cutter bit design optimization and materials improvements.

The oil-and-gas drilling industry has been utilizing modified PDC cutter geometry for improving performance. One of the first reinforcements of beliefs in positive effects of edge geometry changes was in report by Lin et al. in 1992 from conducting laboratory experiments on cutters. Currently, certain geometries are being favored based on limited testing and analysis of the design space. The detailed effect of geometry on attributes such as strength, cutting, wear and the tie to performance has not been fully understood. This paper reports results of laboratory studies, numerical models, and field runs towards building such understanding. Single cutter edge-loading tests, pressurized cutting and wear tests were carried out alongside full-scale PDC bit tests and field runs. Improved analysis techniques were utilized to extract meaningful information from the tests. Numerical models were used to exploit the design space for the geometry. The optimized geometry was selected with greater than 50% strength improvement as indicated by the numerical model. For the optimized geometry, pressurized single cutter lab tests indicated greater than 25% performance improvement in several aspects. Of the field runs in various applications, the largest dataset was in Norway with an ROP increase of 18% among greater than 187 bits run. This study is part of a holistic approach to understanding the thermo-mechanical behavior of PDC cutter drilling as it applies to improving design as demonstrated and drilling practices. The improved cutter geometry has helped customers drill further and faster, which has helped reduce the cost of drilling. There are still improvements that can be made to cutter geometries that will push performance even further. The methods discussed in this paper will help expedite the learning process and help build better insights.