In heavy oil applications, drill bit body and PDC cutter erosion are frequently encountered challenges that can significantly affect the durability and overall drilling performance of the bit. Abrasive formations such as unconsolidated sands, drilling fluids with high solids content, and high hydraulic flow rates are all factors that limit the life of the drill bit, and consequently, there exists an opportunity to improve the economics of heavy oil wells through the development of more abrasion and erosion resistant body materials and PDC cutter substrates.
This paper will discuss the various stages of research and development performed on drill bit hardfacing and PDC cutter substrate materials to improve durability and minimize repair costs in Canadian Oil Sands applications. Hardfacing development was accomplished through microstructural analysis, experimentation with various carbide compositions and particle sizes, and the incorporation of superhard abrasives (hardness values in excess of 5800 ksi) dispersed throughout the hard metal matrix. Moreover, the development of erosion resistant PDC cutter substrates was achieved through novel manufacturing processes and material research. Close cooperation with operators and the ability for rapid field testing of new technologies has enabled the collection of valuable feedback and performance comparisons between close offset wells.
To date, a significant improvement in wear resistance has been achieved in hundreds of runs in the Canadian Oil Sands. These runs consisted predominantly of 10.625 in. and 8.750 in. diameter horizontal intervals, in which the operators typically observed a positive impact on drilling economics. For instance, reduced gage pad wear has resulted in fewer bits falling under-gage, thereby preventing the subsequent bit from having to ream the under-gage section to the correct diameter. Enhanced hardfacing life has reduced bit body erosion surrounding PDC cutters and other brazed components, thus decreasing the number of lost components due to the erosion of supporting material. Furthermore, PDC cutter substrate improvements have reduced the amount of observed carbide loss behind the diamond table in order to mitigate cutter breakage and preserve their formation shearing efficiency.
Additional efforts are currently underway to further develop wear resistant materials tailored to abrasive and erosive drilling environments. These technologies have potential to enhance drilling efficiency and repairability of drill bits in heavy oil applications including, but not limited to, the Canadian Oil Sands.