Technology Focus: Coiled Tubing (June 2019)
Authors: Crabtree Alex 
Published: May 2019

Technology Focus
During the past several years, lean philosophies, methods, and techniques have been applied steadily and increasingly within the upstream segment of the oil and gas industry. Perhaps one of the more notable areas for this growth has been in unconventional well completions and field development with references to such endeavors as the “well factory.” In part, this has been focused on optimizing well and pad construction to establish a uniformity of processes and equipment. This allows a greater focus on elimination of the various forms of waste, as defined in lean concepts, to drive various efficiency gains.
However, applying these concepts to well interventions proves challenging. The coiled-tubing (CT) industry, like other well-intervention segments, has applied lean philosophies to some aspects of its management, operations, processes, and equipment. When it comes to CT application to specific in-well operations, no two wells are the same. Even though the operations may be nominally similar, well variables such as temperature, pressure, depth, and fluids can make it difficult to understand the cause and effect. The continued high activity level in the unconventional and shale well segments in the US has provided a unique opportunity to apply the scientific method to CT interventions because of a reduced number of variables and the fact that the plan/do/check/adjust cycle can be applied. Paper SPE 191689 exemplifies the use of the scientific method for in-well CT operations.
Another way to bring efficiency to operations is through the sharing or compounding of data to increase the sample group. Conflicts of interest or fair-competition concerns can make this approach difficult. One paper in the recommended additional reading list, SPE 194277, may offer a practical solution.
Part of the operational challenges for CT in unconventional wells is the lateral length that must be accessed. Paper SPE 194300 also shows that these challenges are being encountered similarly offshore and how they are being addressed. Additionally, the continued development of high-performance CT steels and workstring designs (paper SPE 194255) drives these significant enabling technologies in meeting the challenges.
The continuing general trend to operate with larger-diameter CT at higher tensile loads brings other operational issues, such as avoiding imparting mechanical damage to the CT’s surface by handling the equipment. Examining how the CT injector might be optimized by design, or by usage, from a finite-element-analysis and a mathematical perspective is discussed in paper SPE 194254 and introduces an interesting factor to the discussion. I am sure that there will be diverse opinions on this work.
SPE 194300 Highly Engineered 2.375-in. Coiled Tubing Provides Effective and Reliable Interventions on 30,000-ft Megareach Wells Offshore Abu Dhabi by Irma Galvan, Global Tubing, et al.
SPE 194277 Remote Monitoring and Modeling of Coiled-Tubing Operations in Real Time by Paul Brown, CoilData, et al.
SPE 192000 Rigless Intervention To Secure Internal Blowout Monitoring Gas Wells Offshore Brunei by Axemi Leong, Halliburton, et al.