Comparison of DAS and FBG Sensitivity for Detecting and Quantifying Small Pipeline Leaks

Document Type

Conference Proceeding

Publication Date

1-1-2023

Abstract

Detecting leaks early and reliably is essential for preventing environmental contamination. However, very small leaks often go undetected using conventional gauges and sensors due to their low sensitivity and limitation to measuring only at discrete gauge locations. Leak detection using optical fiber-based sensors is becoming increasingly popular as they are immune to electromagnetic interference, do not require any electronics at the measurement location, are resistant to corrosion, and enable sensing capability at multiple locations simultaneously and in real-time, with high sensitivity. In this study, the authors experimentally investigate the sensitivity to detect and quantify leaks using two commonly used fiber-optic sensors: distributed acoustic sensors (DAS) and fiber Bragg grating (FBG)-based sensors. Controlled leaks at different flow rates were created in an experimental flow loop with DAS and FBG attached to the outer pipe walls. The strain rate data obtained from DAS was processed using time- and frequency-domain signal processing techniques to detect the location of the leak and quantify the volumetric leak rate as low as 0.07 gallons per minute (gpm). FBGs were used to localize the leak in a quasi-distributed fashion. Since FBGs are responsive to both strain and temperature, the two effects were decoupled using independent temperature measurements to separately study the strain and temperature response due to the leak. The sensitivity to detect leaks was evaluated by comparing the leak signature for both sensors. The effect of environmental noise and background signals on the ability to detect leaks was investigated for different pipe flow rates and leak volumes.

Publication Source (Journal or Book title)

Proceedings of SPIE - The International Society for Optical Engineering

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