Intelligent-Drillstring Field Trials

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This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 92477, "Intelligent Drill String Field Trials Demonstrate Technology Functionality," by M.E. Reeves, SPE, Grant Prideco; M.L. Payne, SPE, and A.G. Ismayilov, SPE, BP plc; and M.J. Jellison, SPE, Grant Prideco, prepared for the 2005 SPE/IADC Drilling Conference, Amsterdam, 23-25 February. Intelligent-drillstring components capable of transmitting data at rates as high as 2 Mbit/sec have been developed and successfully tested in commercial drilling applications. The full-length paper details the lessons learned during intelligent-drillstring field trials and focuses on overall network performance during drilling operations, physical handling, and integration of existing downhole measurement-while-drilling (MWD) tools into the network. Introduction Seven years of engineering and development, funded in part by the U.S. Dept. of Energy, has produced an intelligent-drillstring network capable of transmitting data at rates as high as 2 Mbit/sec. This system makes it possible to obtain large volumes of data from existing MWD/logging-while-drilling (LWD) tools almost instantaneously. Additionally, the system design allows data to be transmitted both upward and downward from hundreds of distributed measurement devices, regardless of circulation conditions. Because every node is uniquely identifiable, the location where events occur along the length of the well can be determined. The bidirectional communication architecture means not only that high-speed transmission of downhole data to the surface is possible, but also that commands from the surface to devices downhole can be sent, received, and acted on. A server at the surface can be used to send information to locations on the rig or, in encrypted form, to operations engineers and managers throughout the world. Technology Overview The intelligent-drillstring system comprises conventional drilling tubulars modified to incorporate a high-speed, low-loss data cable running the length of each joint. The cable terminates at unique inductive coils that are installed in the pin nose and corresponding box shoulder of every connection and transmit data across each tool-joint interface. A second-generation, double-shoulder connection provides a good location for coil placement, with each coil installed in a protective groove in the secondary torque shoulder. When two connections are threaded together, the pin-end coil in one joint is brought into close proximity with the box-end coil of another. A carrier signal in the form of an alternating current flowing through the coil in either segment produces a changing electromagnetic field that induces current flow in the other coil, thereby transmitting the signal to the second joint. The data cable is encapsulated inside a pressure-sealed stainless-steel conduit. In a drillpipe configuration, the conduit passes through the body of the tool joint and then enters into the internal diameter of the drillpipe at the internal upset. Fig. 1 provides a cutaway view showing the location of the inductive coils and conduit in a made-up drillpipe connection. The conduit is held under tension in the drillpipe tube, maintaining its position against the tube wall under most conditions and minimizing interference with mud flow or tool deployment through the center of the drillpipe.