Innovation in Designing Drilling Bits: Integrating Simulations and Bit Cutter Re-Design to Improve Bit Performance

Abstract In deep, abrasive, highly interbedded reservoirs with compressive strengths ranging from 15,000 – 30,000 psi, drilling long drain holes sections with current drilling bit designs proved ineffective. Bit interactions with the formation resulted in high erratic torque, requiring reduction of drilling parameters to a conservative level. This resulted in low rate of penetration (ROP) and ultimately impacting drilling performance. This necessitated the re-evaluation of the bit-formation compatibility to derive possible bit deign augmentations to improve ROP. A detailed analysis was performed on previous bit runs with emphasis on the bits design, cutter technology and dull gradings. This revealed that the bit design could be optimized for drilling longer laterals across these formations while improving ROP performance and bit life. New bit design models based on innovative cutter geometry and bit structural design were run through intensive simulation programs to test their durability and torque levels during drilling. The simulations showed improved results from existing runs, and new trial test bits were manufactured from these designs. These new bits were ultimately deployed in selected wells for evaluation. The trial runs with these newly engineered bits yielded a 70% improvement in drilling ROP across the formations in question. The bits also showed better torque stability throughout the drilling run and drilled longer footage compared to previous runs. The bit life also improved, as these bits drilled over 5000 ft of hole section in a single run, unlike in previous wells that required multiple bit-trips to drill the same footage. Previous wells also required additional reaming trips prior to pulling out of hole due to irregular wellbore geometry. However, on the trial runs with the newly designed bit, the wellbore geometry was considerably better and did not require reaming trips. This was mainly due to the reduced erratic torque and improved bit stability. Post-run bit dull grade analysis showed increased frontal impact resistance, improved durability and higher resistance to wear. Open hole logs were performed without encountering any obstructions or tight spots and subsequent completions were run across the open hole without issues. Ultimately, this re-engineered bit solution led to a 5-day average reduction in well delivery time per well when fully implemented. This resulted in substantial cost savings and improved well delivery performance across the field. This paper will discuss the entire bit re-design and implementation process, from initial analysis of previous bit runs to the actual bit re-design and manufacturing, the successful trial runs, and review of the trial run results. The success achieved with this bit re-design process will open doors for further improvements in bit design and ultimately result in improve drilling performance and drilling cost reduction.