Technology Focus: Coiled Tubing Applications (June 2010)

Abstract

Technology Focus I guess it is no surprise to the people who manufacture coiled tubing (CT) or to those of us in the CT-service industry who actually buy it, but CT is getting bigger. After a decade during which the most common size was 1½ in., the position changed in 2008 when 1¾ in. finally took top spot. Only 1 year later, 2-in. CT took the pole position. What, might you ask, is driving this growth in pipe diameter? The answer is: “Horizontal wells.” In the past few years, we have seen explosive growth in the number of horizontal wells drilled, with much of that growth occurring in the North American shale market. However, the increase in pipe size is driven not only by an increased number of horizontal wells but also because lateral reach is increasing and because completion methods are evolving. Tight-gas-completion methods routinely encompass techniques that use CT for perforating, composite-plug mill-outs, fracture-port ball-seat mill-outs, and fracture-sand cleanouts. The larger-diameter CT is required for greater lateral reach and to enable adequate weight on bit for effective milling operations. Also, because solids removal still requires the same fluid-circulation rates while strings are getting longer, then inevitably, CT diameters must increase to keep surface injection pressures manageable. Bigger, heavier strings inevitably cost more; and because of equipment-size limitations, these strings are subjected to greater bending strain, which in turn results in a shorter working life. One might imagine that we could be reaching an economic limit on string size, but in fact there currently is no sign that this trend is abating. So, is the answer just to build bigger and bigger equipment? One risk of concentrating solely on the CT handling equipment is that the equipment becomes increasingly focused on specific well types and applications, and, in turn, CT loses its versatility for everyday intervention operations. Right now, the jury is still “out,” but it remains a question of whether the various technology initiatives aimed at extending CT horizontal reach will ever meet the operators’ expressed desire for ever-longer horizontal wells and, in turn, how that will influence the CT industry. Coiled Tubing Applications additional reading available at OnePetro: www.onepetro.org SPE 130632 • “Deliquefication of South Texas Gas Wells Using Corrosion-Resistant Coiled Tubing: A 6-Year Case History” by K.L. Poppenhagen, SPE, ConocoPhillips, et al. SPE 130625 • “New Field in East Siberia: Challenges of Performing CT Operations in Vankorskoe Field” by V. Bochkarev, Rosneft, et al. SPE 130579 • “Laminar and Turbulent Friction Factors for Annular Flow of Drag-Reducing Polymer Solutions in Coiled-Tubing Operations” by C.C. Ogugbue, SPE, University of Oklahoma, et al.