Coiled tubing (CT) is increasingly becoming a viable and preferred alternative to joined pipe in a wide range of oil and gas well operations. Consequently, along with being suitable for use in more applications, CT must maintain its integrity under increased operational conditions of pressure, load, and depth. These operational conditions require extensive safety measures during all phases of a Ct project.

This paper presents the objectives, physical setup, procedures, and successful results of full-scale, low-cycle fatigue tests. Researchers tested two different grades of 2-in. CT to refine the CT fatigue-life prediction model and string management system. In addition, a powerful, automatic CT inspection and monitoring system with multiaxial outer diameter and wall-thickness measuring capabilities was tested and validated.

During the tests, the following models and systems have improved and validated:

  • tubing fatigue models

  • string management systems

  • real-time CT inspection and monitoring systems

In CT operations, these models and systems have to be continually improved and validated to better establish the safety margin and prolong the optimal working life of CT strings. This paper demonstrates how these models and systems can be successfully improved and validated.

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