A Tool for Liner Running and Cementing Using Electric-Line Coiled Tubing
Authors: Bybee Karen 
Published: February 2015

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 120992, "The Side Exhaust Liner-Running Tool: A Tool for Liner Running and Cementing Using E-Line Coiled Tubing," by Greg Sarber, SPE, and Mark Johnson, SPE, BPXA; Bob Harris, SPE, and Carl Diller, Northern Solutions; and John Milne and Alan Holloway, Baker Hughes, originally prepared for the 2009 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, 31 March-1 April. The paper has not been peer reviewed.

A new system for running and cementing liners using electric-line coiled tubing (CT) has been proved on the North Slope of Alaska. The side-exhaust liner-running tool (SELRT) provides the functionality to run and release a liner while using a liner wiper-plug (LWP) system to ensure good cement quality. A jointed-pipe liner is conveyed and cemented with the CT containing an electric umbilical. This innovative equipment has proved to be a substantial health, safety, and environment (HSE) benefit and yields savings in rig time.

Introduction

There has been a continuous CT-drilling (CTD) campaign on the North Slope of Alaska since 1994. This program re-enters existing vertical wells and drills horizontal sidetracks in the Prudhoe Bay, Kuparuk, Endicott, and Milne Point fields. These sidetracks typically are drilled through 4 1/2-in. production tubing without pulling the tubing or removing the existing production tree. More than 575 new sidetrack wells have been drilled in these fields since 1994. Before 2001, conventional 2 3/8-in.-outside-diameter CT (electric-line-umbilical free) was in use. When a well reached total depth (TD), the typical completion was a solid/cemented liner followed by CT-conveyed perforating guns. The liner-running tool used a ball-drop system to release the liner and a CT dart/LWP system to ensure that uncontaminated cement was placed accurately 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 measurement-while-drilling (MWD) bottomhole assembly (BHA) was tested. To operate, this BHA required an electrical umbilical inside the CT. This drilling system 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 underbalanced-drilling (MPD and UBD) applications. The electric orienter minimized shale damage by eliminating the pump cycles needed to operate a mechanical orienter. This new equipment provided sufficient time savings to enable a 30% increase in effective rate of penetration.

Unfortunately, some of the productivity gains realized from using the electric-line CT BHA were lost when it came to completing the wells. To run and cement the liner, the CT reel containing the electric line had to be replaced with an electric-line-free reel to use the existing liner-running equipment. Reel swaps are an HSE risk when conducted in the middle of drilling operations, especially when conducted in Arctic winter conditions; the reel exchange consumed some of the time-savings benefits of using the new drilling BHA, additional operating costs were required to inventory two types of CT, and exchanging reels caused a delay from when the well reached TD until the liner was on bottom.