Field Performance of New Coiled Tubing Manufacturing Technology and Comparisons With Laboratory Performance

Abstract

New coiled tubing manufacturing technology comprising new coiled tubing materials and new manufacturing processes was developed and commercialized recently. The new technology uses new steel chemistries and new heat treatment processes for full microstructure transformation to produce improved and uniform microstructure and properties along the entire coiled tubing string, including bias and seam welds. Coiled tubing strings based on the new technology showed major coiled tubing performance improvements in laboratory and test-well testing. This paper evaluates performance of the new coiled tubing technology in real-life field operations to determine effects of field usage on behavior and properties of the new coiled tubing materials. Additional laboratory testing and evaluation following the field use provide insight into the remaining life of coiled tubing strings, effects of field use on material properties and behavior, and relationship between laboratory testing and actual field use. Coiled tubing produced by the new manufacturing technology has been put through extensive field use in various field operations and environments. Field usage data and results have been collected during commercial operations with coiled tubing made of the new 125-ksi grade material. At the end of field use the coiled tubing was retrieved for laboratory testing and evaluation. Residual and total fatigue life, mechanical properties, ballooning, and effects of operational environments were evaluated along the coiled tubing string and related to bending cycling, pressure, and environmental exposure. The new 125-ksi grade coiled tubing field operations and subsequent laboratory testing and evaluations confirmed major coiled tubing performance improvements previously observed in laboratory and test-well testing. Usable coiled tubing string life, including the life of bias welds, was more than twice the life of a comparable conventional 110-ksi grade coiled tubing string.