Innovative Non-Planar Face PDC Cutters Demonstrate 21% Drilling Efficiency Improvement in Interbedded Shales and Sand

Abstract

Traditional polycrystalline diamond cutter (PDC) technology has made tremendous gains over the past decade with corresponding footage and rate of penetration (ROP) improvements in drilling performance. The remaining challenge is managing interbedded formations with competent stringers while maintaining drilling efficiency and the highest ROP potential, such as those present in the 6 to 6⅛-in. Pinedale Anticline production hole and the 12¼-in. Cana intermediate section. By modifying the standard planar PDC cutter face geometry with novel shallow recessed features, a demonstrated improvement in drilling efficiency was observed in these applications and an increase in attained footage. Extensive analysis in Pinedale runs indicated this cutter design benefits a lower mechanical specific energy (MSE) in the shale and sand, shorter day curves, and higher average ROP per unit of motor horsepower. Initial runs in the Tonkawa sands of the Cana intermediate have started to show similar trends. The successful field runs have been supported by in-depth analysis and study of cutting efficiency including, single-point cutter testing in a pressurized vessel, atmospheric vertical turret lathe testing, and full-scale PDC bit laboratory testing in a state-of-the-art downhole drilling simulator. The results of this work improved the understanding of the thermo-mechanical behavior of cuttings formed by the drilling action of a PDC cutter in these applications. This study is part of an innovative approach to manage rock cuttings, cutting efficiency, and thermal loads as it applies to PDC durability in state-of-the-art drill bit designs. The design changes have improved cutting efficiency and aggressivity, which has improved the ROP of bits in abrasive sand and in the shale sections. This paper provides documentation and visual demonstrations of the features and benefits seen in the single-point test apparatus, the downhole simulator in the laboratory and in the field with case studies compared to offsets of standard bits with planar PDC cutters.

Failure analysis and optimum structure design of PDC cutter

“…Wang et al [11] analyzed the relationship of the cutting angle of PDC bit cutter and broken rock effect. David et al [12] designed a kind of non-planar face PDC cutters, and won a good test effect. However, although the failure causes were presented in a qualitative analysis way for many years, little attention has been paid to the quantitative analysis.…”

“…For the failure of conventional cylindrical PDC cutter, the usual solution is to groove on the surface of WC or change process, shape and structure of the proportion of PCD, so as to improve the performance of composite sheet itself, but on the combined surface of internal stress and shear stress distribution and the improvement of the size are very limited [12]. Therefore, this article in-depth analysis of the failure mechanism, proposed the multi-face (i.e., Non-planar) PDC strengthen cutter in the view of the structure and relative process skill, will extend the service life of PDC bit, and have important practical application value and engineering significance.…”

Numerical modeling on drilling fluid and cutter design effect on drilling bit cutter thermal wear and breakdown

“…The previous studies on PDC drill bit crown and PDC drill bit cutter had proposed several design optimizations based on laboratory experiments (Curry et al 2015;Oliveira et al 2015;Stockey et al 2014;Azar et al 2013;Yahiaoui et al 2013) and finite element modeling (FEM) (Oliveira et al 2015;Rani et al 2015;Stockey et al 2014;Al-Muhailan et al 2013;Ju et al 2014;Freeman et al 2012). Oliveira et al (2015) proposed a new drill bit cutter design called dual-chamfer cutters for drilling in interbedded formations.…”

“…Their work limitations were the nonexistence of experiments on the effect of different drilling fluid types on cutter thermal wear. Stockey et al (2014) had modeled the FEM-CFD to analyze the thermal wear on planar and nonplanar cutters. Stockey et al (2014) applied a uniform heat flux to both cutters, but they did not perform any modeling on the drilling fluid cooling effect on the drill bit cutter to reduce the thermal wear.…”

“…Stockey et al (2014) had modeled the FEM-CFD to analyze the thermal wear on planar and nonplanar cutters. Stockey et al (2014) applied a uniform heat flux to both cutters, but they did not perform any modeling on the drilling fluid cooling effect on the drill bit cutter to reduce the thermal wear. Others (Oliveira et al 2015;Rani et al 2015;Al-Muhailan et al 2013;Ju et al 2014) also did not consider the drilling fluid cooling effect on drill bit cutter.…”