The Side Exhaust Liner Running Tool: A Tool for Liner Running and Cementing Using E-Line Coiled Tubing

Abstract

A new system for running and cementing liners using Electric line coiled tubing has been proven on the North Slope of Alaska. The SELRT, the Side Exhaust Liner Running Tool, gives the functionality to run and release a liner while utilizing a liner wiper plug system to ensure good cement quality. A jointed pipe liner is conveyed and cemented with the coiled tubing containing an electric umbilical.This innovative equipment has proven to be a substantial HSE benefit and savings in rig time when compared to a more conventional liner running system. Older systems used in Alaska required switching to an electric line free coiled tubing reel prior to running and cementing liner. Jointed pipe liners up to 3,700' long have been successfully run and cemented with electric line coil using the SELRT system, saving an average of 19 hours of rig time per well. This paper will describe the system development including pumping test slurries of cement through electric line coiled tubing, confirming that dropping balls is possible through electric line coiled tubing and the development and use of the new liner running equipment. Several successful liner running and cementing jobs will be reviewed. This is now the standard liner running equipment used for wells drilled with coiled tubing in the Prudhoe Bay field. IntroductionThere has been a continuous coiled tubing drilling campaign on the North Slope of Alaska since 1994. This program reenters existing vertical wells and drills horizontal sidetracks in the Prudhoe Bay, Kuparuk, Endicott and Milne Point fields. These sidetracks are typically drilled thru 4-1/2" production tubing without pulling the tubing or removing the existing production tree. (See Figure #1). Over 575 new sidetrack wells have been drilled in these fields since 1994. Prior to 2001 conventional 2-3/8" OD coiled tubing (electric line umbilical free) was in use. When a well reached TD the typical completion was a solid/cemented liner followed by coiled tubing conveyed perforating guns. The liner running tool used a ball drop system to release the liner and a coil dart/liner wiper plug system to ensure that uncontaminated cement was accurately placed behind the liner. This system proved quite reliable and robust and accounted for the majority of wells drilled up to 2001. In 2001 a new MWD BHA was tested. This BHA required an electrical umbilical inside the coiled tubing to operate. There were significant advantages to this drilling system. It provided higher data telemetry rates, more real time downhole information and better directional control using an electrical downhole orienter instead of a mechanical orienter. This system proved to be especially beneficial in managed pressure and under balanced drilling applications. The electric orienter minimized shale damage by eliminating the pump cycles needed to operate a mechanical orienter. This new equipment provided enough time savings to enable a 30% increase in effective ROP.Unfortunately, some of the productivity gains realized from using the e-line coil BHA wer...