This paper describes this first commercial deployment of a third-generation double-shouldered, double-start, rotary connection run on the Discoverer Deep Seas drill ship at Walker Ridge 678 in 7,016 feet of water. The 5–7/8 inch OD, 26.30 ppf, S-135, Range-2 drill string was used to drill the planned 28,000 feet vertical well. Lessons learned and future recommendations are presented.
New developments in drilling tubulars are rapidly evolving and represent enabling technologies for the industry's continued advancement of drilling deeper, further and more cost-effective wells. The current trend to drill offshore in deeper waters, longer extended reach wells and record setting ultra-deep wells continues. Some operators have wells of 40,000 to 45,000 TMD in the planning stages. In response to this need, the development of third generation, ultra-high torque connections were developed and released in 2006. These third generation double-shouldered connections are the industry's first family of connections designed to meet the specific and different needs of each pipe size. The thread form is a doublestart thread that reduces the number of revolutions to assemble the connection by 50%. The thread form also provides a unique dual-radius thread root that offers a step-change improvement in fatigue resistance. The new connection provides increased mechanical and hydraulic performance compared to earlier high-performance connections while also providing fatigue performance greater than standard API connections.
These connections can facilitate more challenging wells, provide increased cost savings and reduce risk during the well construction process. Conservative estimates suggest that the new connections will save approximately 7–1/2 hours in cumulative trip time for a 20,000 foot well.
The first third-generation double-shouldered rotary connection was announced and released on September 25, 2006 at the SPE Annual Technical Conference and Exhibition. At that time market activity had created an extended backlog of 14–16 months for new drill pipe production delaying the first deployment until early December of 2007. Since the industry first began rotary drilling, wells have continued to be more challenging: greater total depth, further extended reach, in deeper water, in areas with increased environmental sensitivity, and through various formation challenges in order to reach hydrocarbon targets. Drill string components have evolved, as well, enabling operators to meet these challenges. The development of rotary-shouldered connections has also had an impact on rig operations.
This paper will review the evolution of rotary-shouldered connection with emphasis on the effects of operations on the rig floor. The first deployment of the third-generation double-shouldered rotary connection will be covered in detail with focus on the effect of the connection features on drill stem running operations. A primary benefit of using the third-generation double-shouldered rotary connection is the increased speed of make-up and breakout compared with the second generation connection. Rig time savings on the first deployment will be evaluated and expected saving for future operations forecasted. Finally, connection damage and repair cost resulting from the deployment will be evaluated.