In volatile times, when oil prices are in a decline, efficiencies and asset utilization are critical elements to ensure sustainability in the market for both operators and service companies. However, maximizing utilization and pushing equipment to the maximum could potentially have negative repercussions and ultimately result in failures causing loss of time and other potential damages. Thus is it critical to closely monitor and evaluate the assets conditions to ensure both safe and efficient operations are performed.

In the case of coiled tubing (CT) strings, monitoring and proper evaluation can be performed by utilizing an infield nondestructive evaluation (NDE) device that employs magnetic flux leakage (MFL) to detect flaws and monitor, wall thickness, outer diameter, and various other properties. The real-time device requires no direct contact with pipe, and its compact design allows it to be run continuously throughout the life of the CT. Damage can then be detected and managed before a failure occurs. The ultimate goal is to reduce CT failures while increasing CT longevity throughout the operations.

This paper covers three specific examples of NDE inspection conducted on site that increased the utilization of the CT string without compromising the service quality delivery. It also reviews the various parameters that were monitored and evaluated on location and the decision-making process used to keep the strings in service longer than previous methods would have allowed thus safely increasing the utilization and improving the efficiency.

The first two cases are out of Texas, USA. The objective of the NDE was monitoring the pipe for corrosion or physical plastic deformation. This region regularly performs high-pressure cycling operations and in the past relied mostly on calculated fatigue models with significant derated values and safety factors to retire strings from use. Utilizing the scanning devices from after manufacturing through the strings' life allowed both the operator and the service company get more useable footage and still retire the strings after getting indications of irreversible geometric changes. They were able to plan and control the CT retirement around operational well plans to ensure no delays were seen in the field.

The third example is out of Alberta, Canada. A CT string being used on a long-term project was damaged. The NDE inspection allowed for continued use of a pipe that had visible surface damage. In the past, this string would have been immediately retired and removed from service after a mechanical defect of the same nature was observed; however, the NDE device aided in adressing the severity of the damage, by MFL, and monitored its progress while continuing to use the string. The 2.375-in. string was able to be run an additional 53,203-m [174,550-ft] in a safe and controlled manner before reaching retirement.

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