Abstract
Higher expectations for safety, well integrity and Coiled Tubing (CT) string durability have resulted in increasing demand for periodic inspections and continuous monitoring of CT strings. As such, leading companies in the Middle East are requiring more stringent inspections. In this paper, we outline the challenges presented by stricter inspection requirements amid the recent trend for heavier walled strings. We also discuss the engineering solutions we employ to address these new challenges and share concrete results that proved effective.
The new inspection requirements go beyond the stringent API-5ST-SR37 specification for new CT strings. The trend towards heavier wall thickness in CT strings makes the new specifications even more challenging as this increases the separation between the external inspection sensors and any internal flaws. This separation degrades the sensitivity of the inspection tools to internal flaws. To address these challenges, we revamped our CT inspection and continuous monitoring solutions. Specifically, we have developed the following solutions:
A new software version for our ECTAS III inspection system with advanced signal processing algorithms that improve sensitivity to difficult flaws, such as narrow longitudinally oriented mass losses on the outer or inner tubing surface.
Significant hardware and software enhancements to our continuous, real-time CT monitoring system.
These enhancements yielded significantly better results as proven by data collected upon scanning third-party certified reference standards. These standards come from CT samples supplied by various mills, are EDM machined with reference flaws and independently certified according to industry specifications that we aim to comply with.
We share the performance results of the scans through plots depicting the Magnetic Flux Leakage (MFL) response of the reference flaws. The results show an increase in tool sensitivity to flaws evidenced by a minimum increase of 63% in the signal to noise ratio (SNR) across key reference flaws. This increase in the SNR depends on the wall thickness of the reference standard as well as the flaw geometry.
Our results show that our probability of detection (POD) has improved dramatically. We are now for the first time able to detect the most difficult reference flaw of the new specifications: the longitudinal inner diameter (LID) flaw. The results highlight the unprecedented achievement of a minimum SNR of 3 to 1 on LID flaws in tubing 2 3/8 inch in diameter and up to 0.276 inch in wall thickness. Our technological improvements have ensured continuation in meeting industry requirements amid challenging changes in CT specifications. We continue to contribute to leading CT operators’ endeavor to ensure higher CT quality, enhance safety and drive operational excellence.
