The Khurais project, located in the central part of Saudi Arabia near Riyadh, is the largest project in Saudi Arabia. Comprising drilling and completion of 168 horizontal producer wells at 12,000 ft measured depth (MD) each, one of the success measures of this project revolves around its expeditious completion. With the focus on this objective, a collaborative effort was implemented to analyze and assess the drilling challenges, how best to address them, and to apply the lessons learned throughout the duration of the project. This collaboration included service companies, drilling engineers and rig foremen coupled with an on-site bit design engineer. As a result of this teamwork, improvements were achieved in a short period of time, providing the confidence that the objective will be met. One of the primary objectives was to produce a drill bit that would provide the highest rate of penetration (ROP) possible without compromising steerability. The 12¼-in. hole section of the wells is particularly demanding, with a build section from 0° to 87° through interbedded formations. Achieving a desired buildup rate with good ROP can be negated by a bit that may be too aggressive and that has poor directional control.
Through the group effort, the team was able to develop an optimized 12¼-in. polycrystalline diamond compact (PDC) bit that resulted in a ROP increase by over 40% since the project’s onset, in only three months. With the ultimate goal of increasing ROP more than 50%, the new bit design is proving to be a definitive solution. The authors will describe the process and design analyses that were used to develop the PDC bit design for the application, from the collaboration to the use of post-design/parameter analysis after the run. They will also illustrate the importance of post-action reviews of lessons learned to apply the correct operating practices, the desired bottom-hole assembly (BHA), and bit design in the achievement of record ROPs.