Hybrid Bit Technology Expands Application Range in Harsh Rock Environments

Abstract

When drilling in extreme environments, the integration of the latest advancements in materials engineering and cutter technology are crucial to maximizing drilling efficiency and reducing trips. Recent advances in hybrid bit technology have expanded the application range into lithology intervals that feature high compressive strength, high abrasivity and low drillability. By fusing existing technologies such as PDC and diamond impregnated cutting structures, designers have improved existing designs so they feature both optimized cutting element placement for extending bit durability and an engineered mix of diamond impregnated material strategically placed in critical wear-prone areas of the bit to increase exposure on hard and abrasive lithologies. These design changes also take into account the effects of a progressive combination of shearing and grinding rock failure mechanisms to maximize drilling efficiency.After initial applications in the Sub-Saharan region of the Congo, this bit technology has been featured in several applications across the world. These cases include runs onshore Jordan with highly interbedded lithologies; foothills area of Colombia drilling in rocks exceeding 25ksi UCS and offshore runs in Mexico within the middle and lower cretaceous areas with lithologies containing up to 10% Chert.In these case studies, the use of hybrid drill bit technology has reduced costs and NPT in situations where it would typically take a number of impregnated, PDC and tungsten carbide insert bits, many using different drive systems, to reach total depth. These cases also describe the different characteristics and drillability of the rock types, as each demands specific bit design features and parameters to be failed in the most effective manner.During the evolution of the hybrid design, the importance of PDC cutter selection played a crucial role in the design's success. Cutter technology was adapted to provide superior abrasion and thermal resistance, better suited to combat the high abrasivity of the formations. Additionally, the cutting edge geometry was modified to provide increased toughness, avoiding premature cutter edge overload to maximize the length of the bit run.