Leakage Detection Using Distributed Acoustic Sensing in Gas Pipelines

Area of Science:

• Pipeline integrity and safety
• Fiber optic sensing technologies
• Acoustic monitoring systems

Background:

• Gas pipeline leaks pose significant safety and environmental risks.
• Traditional leak detection methods have limitations, especially for unpiggable pipelines.
• Distributed Acoustic Sensing (DAS) offers a potential non-invasive monitoring solution.

Purpose of the Study:

• To evaluate the performance of DAS for gas pipeline leak detection.
• To compare different fiber optic cable types and deployment methods (internal vs. external).
• To assess the impact of leak characteristics and pipeline installation on detection accuracy.

Main Methods:

• Experimental setup with a 21m steel pipeline simulating leaks of various sizes, orientations, and flow velocities.
• Testing four fiber optic cable deployments: three internal and one external.
• Analyzing DAS data using time-domain vibration intensity and frequency-domain spectral methods.
• Comparing detection performance under supported and buried pipeline conditions.

Main Results:

• Leak detectability is influenced by flow rate, leak size/orientation, installation, and fiber optic setup.
• Internally deployed black and flat cables showed higher sensitivity, particularly for bottom leaks and high flow velocities.
• Buried pipeline configurations reduced leak detection due to damping effects.
• External cable performance varied based on mechanical coupling.

Conclusions:

• Internal fiber optic cable deployment for DAS leak detection is a novel and practical approach.
• This method is suitable for pipelines where conventional inspection is not feasible.
• DAS performance is highly dependent on the interplay between fiber optic sensing and pipeline environment.