The Evolutionary Journey of Completion Tubing to 100% Non-Metallic Composite Material

Abstract

AbstractNon-metallic tubing manufactured from fiberglass have been around for decades, and for good reason with multiple physical advantages over carbon steel tubing. However, this has also came with certain physical constraints such as the type of tubing connections and material brittleness with resultant low-pressure ratings. This has restricted a more widespread use of the material, particularly for downhole applications. In recent years, extensive research and development has evolved to manufacture 100% non-metallic composite tubulars with increased mechanical strength combined with high performance machined threads.The development of non-metallic composite tubulars have been in progress for many years, obstacles to the manufacturing process to deliver a material that was suitable for downhole conditions were numerous. The fully non-metallic fiberglass tubular is manufactured with aromatic amine cured epoxy resin, which not only provides the required strength but also an effective resistance to the harsh downhole conditions. Deep water supply wells that provide water injection are ideal candidates for this technology. The material is corrosion resistant, lightweight, zero maintenance, extremely durable with a superior hydraulic performance over carbon steel.The challenges of using carbon steel tubulars in harsh water environments are well known, and can lead to premature failure of the completion. Such failure can result in flow circulation across the electrical submersible pump (ESP) eventually leading to pump failure due to excessive heat in the motor. Fiberglass lined carbon steel protects the inner part of the tubing but still leaves the external side exposed to the harsh environment. The next step in the evolution for tubulars exposed to harsh conditions is 100% non-metallic manufactured tubulars. A custom designed resin system and manufacturing process with precise winding angle patterns delivered this high strength and chemically stable product. These properties allow for a maximum running depth of 12,000 ft, a maximum working pressure of 2500 psi and an expected life expectancy in the 10's of years. The tubing joints have API specification composite machined threads and are made up similar to traditional carbon steel tubing but requiring less torque.The successful deployment of 100% non-metallic composite tubulars in ESP powered water supply wells is another step towards increased utilization of this technology. A review has been completed of the manufacturing process, flow assurance, design integrity improvements and economic analysis of the 100% non-metallic fiberglass tubular. This completion design ensures well integrity & prolongs the lifetime of the assets and is in-line with the adoption of circular economy practices, simultaneously providing cost effective solutions and ensuring continuous improvement.