Drillstring Technology for World-Class Extended-Reach Drilling

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 18512, "Drillstring Technology Vanguard for World-Class Extended-Reach Drilling," by M.J. Jellison, SPE, and R.B. Chandler, SPE, Grant Prideco; M.L. Payne, SPE, BP; and J.S. Shepard, SPE, GlobalSantaFe, prepared for the 2007 Offshore Technology Conference, Houston, 30 April-3 May. Projects that will expand the extended-reach-drilling (ERD) envelope are in the planning stage in various parts of the world. Drilling engineers no longer are wondering if 50,000-ft ERD wells can be drilled but how this can be accomplished safely and efficiently. It has been estimated that the last 10% of the drilled interval can account for 50% of the total drilling cost. The full-length paper discusses the latest drillstring technologies that are essential to achieve the ERD targets planned for the future. Advanced Material Technologies Industry publications have presented the idea of using nonsteel drillstrings for reduction of torque and drag loads in extended-reach (ER) wells. Other torque- and drag-reduction and management tools and techniques that have proved successful are lower in cost, thus being the preferred methods for meeting current ER torque and drag challenges. The competition of these alternative technologies has inhibited the development of commercially available nonsteel drillpipe. The direction toward longer-departure ER wells has led to increased consideration recently for commercially available nonsteel drillpipe. Generally, three advanced materials should be included in this consideration—carbon-fiber-based composites, titanium, and aluminum. Each has been used in drillstrings with varying degrees of success. Each material has strengths and weaknesses relating to its use for drillpipe to drill ER wells and other critical applications such as ultradeep drilling and deep water. Carbon-Fiber-Based Composites. Composite drillpipe (CDP) is manufactured by winding carbon fibers over a mandrel while applying an epoxy matrix to encase the fibers and seal the assembly. CDP manufactured to date has had steel pin-and-box tool joints similar in design to conventional steel-drillpipe connections. The steel tool joints are attached to the composite tube during the winding process in which the carbon fibers are placed over specially designed ends of the tool-joint members to bond with the composite tube and resist fatigue in service. Currently produced CDP is approximately three times the cost of conventional steel drillpipe. As the technology improves and the capabilities of carbon-fiber manufacturers advance, this price differential may decrease. CDP offers several potential advantages over conventional steel drillpipe that could make CDP particularly well suited to ERD and other critical drilling applications.