New Hybrid Bit Technology Provides Improved Performance in Conventional Intervals

Abstract The increasing emergence of hybrid drill bit technologies in recent years is pushing drilling performance to new levels that were previously unattainable by conventional designs. One example of a hybrid bit technology uses a combination of gouging inserts and shearing PDC cutters to increase the overall effectiveness of rock removal. In two and a half years of development, this hybrid gouging / shearing cutting structure has consistently demonstrated a superior average ROP over rollercone bits, as well as improved PDC cutter durability and lower reactive torque compared to traditional PDC bits. Until recently, the majority of gouging / shearing hybrid bit applications were in surface intervals drilled by six-bladed, 16mm cutter designs. This configuration is adept in enhancing ROP and durability in challenging formations such as gravel and boulders, which normally cause severe impact damage to PDC cutters. However, to push the benefits of the hybrid technology into new territory, significant design changes were made to optimize its performance in the newly targeted applications. In high ROP intervals, lowering the blade count of the bit has been shown to provide two key benefits: firstly, reduced cutter density increases the depth of cut and work rate for each PDC cutter, thereby increasing the aggressiveness and ROP potential of the design. Secondly, it enables more geometrical freedom for a hydraulic configuration that better suits high ROP and thermal demands. Unlike the six- bladed designs, the hydraulic layout of the reduced blade count designs incorporates separate nozzles dedicated to both the gouging inserts and PDC cutters on each blade. The ability to direct high velocity drilling fluid to both cutting structures promotes more effective cooling and removal of cuttings. The first instance of the updated hybrid technology was realized with a four-bladed, 12.25 in. diameter design used in a series of runs in Western Canada, drilling competent formations consisting primarily of shale with interbedded sandstones. The hybrid runs in these areas have exceeded the ROP typically achieved by six-bladed PDC bits in offset wells, and in certain cases, recorded average ROPs of over 310 ft/hr while still maintaining superior torque management throughout the entire run. Additionally, the dull conditions of the bits have repeatedly demonstrated reduced PDC cutter impact damage and thermal wear compared to conventional PDC designs. More development is currently underway to further expand lighter-set hybrid designs into more diverse applications.