High-Speed Wired-Drillstring Telemetry

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 113157, "High- Speed Wired Drillstring Telemetry Network Delivers Increased Safety, Efficiency, Reliability, and Productivity to the Drilling Industry," by M. Hernandez, SPE, D. MacNeill, SPE, and M. Reeves, SPE, IntelliServ, and A. Kirkwood, S. Lemke, J. Ruszka, SPE, and R. Zaeper, SPE, Baker Hughes, originally prepared for the 2008 SPE Indian Oil and Gas Technical Conference and Exhibition, Mumbai, India, 4-6 March. The paper has not been peer reviewed. High-speed wired drillstrings enable two-way wireline communications between bottomhole assemblies (BHAs) and surface systems. Compared to even the most advanced mud-pulse telemetry (MPT), this new capability allows reliable communication with rotary-steerable systems (RSSs), measurement-while-drilling (MWD) systems, and logging-while-drilling (LWD) systems at data rates tens of thousands of times faster than before. The full-length paper describes the system development and discusses in detail the advantages immediately attainable when complete, memory-quality, drilling and evaluation data are provided instantaneously at surface while drilling. Introduction In 1964, a mud valve was suggested to transmit data up the mud column. In the 1970s, transmission of data from tools in the BHA to the surface was achieved. This system, MPT, used pressures pulses created in the downhole tools and transmitted through the continuous column of drilling fluid to surface where they were detected by use of a pressure transducer and then decoded. This revolutionized the directional-drilling industry by providing the directional driller with real-time information for determining the geometric position of the wellbore and steering-system performance. This resulted in significant gains in directional-drilling efficiency and accuracy while simultaneously reducing risk. Companies soon recognized the value of MPT and developed formation-evaluation devices within the BHA. Transmission of these data to surface in real time allowed the well trajectory to be referenced to geological features. Initially, natural gamma ray (GR) and basic resistivity devices were introduced, and this soon expanded to an ever-increasing range of sophisticated devices. These devices provide a wide range of data sets, equivalent to wireline-acquired data in quality but acquired in real time very soon after the formation was drilled. To take full advantage of these measurements to influence decisions in real time, a dramatic increase in data-transmission rates from downhole to surface was required. MPT technology continuously improved to allow transmission rates of up to approximately 20 bits/second (bps) in practice. This, however, still fell short of the transmission rates required to maximize real-time use of the latest LWD systems.