Composite Spoolable Pipe Development, Advancements, and Limitations

Abstract

Abstract Spoolable metallic pipe is an important established technology in the oil industry for downhole and pipeline applications. Efforts have been made in recent years to develop a complementary spoolable composite pipe technology capable of extending the performance boundaries characteristic of metal pipe. It is anticipated that light-weight, corrosionresistant, long-length composite pipe has the potential to significantly improve both onshore and deepwater exploration and production operations. Several applications are currently being explored to use spoolable composite tubulars including: onshore and offshore pipelines, subsea injection lines, well workover/intervention services, flowline cleanouts and surveys, wellbore completions and coiled tubing drilling. Large-diameter (> 6-inch), long-length, composite pipe is also being considered for future development as flexible risers and subsea pipelines. Concepts for fabricating long-length spoolable composite pipe were first introduced in the late 1960's, but the technology was not widely accepted nor applied. Research initiated by Conoco in the late 1980's developed composite design concepts which demonstrated the feasibility of the concept of spoolable composite pipe and explored application opportunities. The effort, working in cooperation with the composites industry, culminated in the formation of companies in the United States and Norway to manufacture spoolable pipe and ignited the interest of several other companies in the United States and Europe. The loads and strains imposed on spoolable pipe extend beyond classical boundaries resulting in complex design and mechanics issues. Combined mechanical and pressure loads imposed during spooling causes steel pipe to experience plastic yielding which eventually leads to failure. Although composite pipe has the potential to perform repeatedly at high loads better than steel, it can experience performance degrading effects as well, which must be addressed in design. The ability to repeatedly spool and deploy composite pipe, even when loaded by high pressure, is a unique characteristics of composites made possible through tailoring the mechanical properties to address specific design requirements. This paper provides a comprehensive review of spoolable composite tubular products under development for the oil and gas industry, discusses advanced design concepts, identifies current limitations, and describes additional opportunities for application development. Introduction Composite materials have been investigated during the last decade to explore how they could be designed and utilized to expand the performance limitations imposed by steel in spoolable pipe applications.1–41 Although the cost of composite pipe is expected to be greater than carbon steel pipe, the corrosion resistance, lighter weight, low thermal conductivity, design flexibility, long service life, and enabling capabilities promise to make composites cost-effective for many applications. Deployment from a spool saves time and expense and the elimination of a large number of connections provides a significant cost and reliability advantage for both steel and composite pipe. Composite tubing can be tailored to exhibit unique anisotropic characteristics which optimally address burst and collapse pressures and tensile and compression loads, as well as the high strains imposed by bending. Composites can be designed to be more resistant to fatigue than steel coiled tubing, especially when combined loads impose strains which force the steel tubing into plastic deformation.