A Tapered OD Coiled Tubing System (TODCTS) enabling the deployment of multiple outer diameter (OD) coiled tubing sections in a single string is being developed.1 By employing larger OD tubing sections near the top of the string and smaller OD sections near the bottom of the string, the tension along the string length is reduced while maintaining sufficient flow capacity for well intervention operations. The TODCTS can enable intervention service in deeper wells or installation of multiple OD velocity strings with the diameters optimized based on well production requirements.

This paper describes the development plan, system and component design, and the results of analyses and tests conducted to verify that the the tapered connector and surface equipment meets the requirements necessary to deploy the connector and adjoining strings of different ODs.

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