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Drilling rate of penetration (ROP) is one of the variables that influences well delivery timing and cost. ROP is affected by many factors, including but not limited to rock strength, well profile, bottom hole assembly (BHA) design, challenging formations per section, and drill bit selection. In one of the drilling projects in the Middle East, the primary method chosen to improve well delivery is to focus on optimizing the drill bit design to improve ROP while delivering other drilling objectives. As the project progressed, the ROP plateaued in most of sections in the field. The drilling team collaborated with the drill bit engineering to launch a drill bit optimization campaign in various hole sizes ranging from 16-in to 6⅛-in. Since fixed-cutter bits are predominantly used in these sections, improvements are made to the existing drill bit designs by replacing the cutting elements with more efficient 3D polycrystalline diamond compact (PDC) cutters or 3DC. 3DC cutters have different shapes, uniquely designed to tackle different drilling challenges. Using an in-house petrophysical log analysis program, each formation drilled in this field was analyzed and drilling challenges and ROP values were compared against previous performance. This information paired with finite element analysis (FEA) for dynamic drilling simulation was used to optimize drill bit selection. This conceptual workflow was followed to avoid costly field tests and ensure that the newly designed drill bit performs flawlessly downhole. Other design elements, such as choosing bit body material, were also incorporated by converting matrix-bodied to steel-bodied, which not only improved the ROP but also reduced the cost-per-foot (CPF). Initially the bit optimization program enabled ROP improvement in the 16-in section by 36% from 53 ft/h to 73 ft/h by replacing the roller-cone bit with a matrix-bodied fixed-cutter bit. Moreover, the drilling team further improved their performance, achieving 118 ft/hr. ROP when using the steel-bodied bit. With successful deployment of 3DC cutters in Middle East, ridged diamond element was introduced in the 8½-in section and successfully improved overall ROP by 11%. In addition, the 6⅛-in section showed 25% improvement in ROP following several design iterations that utilized two different types of 3DC cutters. By the end of the drill bit optimization campaign, the operator was able to improve the drilling curve and save up to 2.5 days per well. The 3DC cutters also helped eliminate the risk of bit failure in the 8½-in section, wherein offset wells several bits were required to complete the section. With the performance mindset, new technology deployment made it faster to test new bit designs. This helped with getting early data point for analysis before being able to test in the different fields in the area. |
