Pipeline Acoustic Source Location Using Moving Pig
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Solution Overview
Problem
Monitoring large and complex pipeline networks, especially underground or sub-sea installations, is challenging due to their size and location, and existing methods like fibre optic distributed acoustic sensing struggle to accurately locate acoustic sources outside the monitored sections or with multiple sources.
Innovation Solution
The method involves using a fibre optic distributed acoustic sensor with a sensing optical fibre along the pipeline and introducing an object, such as a pig, to analyze acoustic signals as it moves, differentiating between signals from various locations by attenuating or blocking acoustic signals from upstream or downstream sections, allowing for precise source location even outside monitored areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If fibre optic distributed acoustic sensing is used to monitor pipelines, then monitoring coverage of large pipeline networks is improved, but the ability to accurately locate acoustic sources outside monitored sections or with multiple sources deteriorates
Solution Approach 1:
A pig is introduced as an intermediary object moving through the pipeline to actively modulate acoustic signals. The pig's movement creates time-varying acoustic attenuation that serves as a reference pattern, enabling the system to distinguish between acoustic sources at different locations along the pipeline, thereby improving location accuracy while maintaining extensive monitoring coverage
Solution Approach 2:
The system utilizes the periodic movement of the pig through the pipeline as a time-based modulation mechanism. By analyzing acoustic signals during different phases of the pig's movement (approaching, passing, and moving away from sensing locations), the system can discriminate between multiple acoustic sources and accurately locate them, resolving the precision issue while preserving broad coverage
2Loss of information
If acoustic signals are transmitted along the pipeline within pressurised fluid, then detection range of acoustic sources is improved, but discrimination of acoustic source locations deteriorates due to signals from remote locations being detected
Solution Approach 1:
The system uses the pig's movement as a feedback mechanism to actively probe the acoustic environment. By monitoring how acoustic signals change as the pig moves through different positions, the system receives feedback about signal attenuation patterns that reveal the locations of acoustic sources, enabling precise discrimination despite long-distance signal transmission
Solution Approach 2:
The system transitions from static acoustic monitoring to dynamic monitoring by introducing the moving pig. The pig's continuous movement creates time-varying acoustic conditions that allow the system to distinguish between acoustic sources at different locations based on when and how signals are attenuated, improving location discrimination while maintaining extended detection range
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively extends the sensing capability of distributed acoustic sensors to locate acoustic sources along pipelines, including leaks and persistent noise sources, enhancing leak detection and maintenance efficiency by discriminating between acoustic signals from different sections of the pipeline.
Implementation Method 1
monitoring at least part of a conduit using a fibre optic distributed acoustic sensor comprising a sensing optical fibre arranged along a path of the conduit
Implementation Method 2
acoustic signals may be transmitted along the conduit, for instance within the fluid within the conduit which may be pressurised
Implementation Method 3
analysing the acoustic signals detected at at least one sensing location of the sensing optical fibre as the object moves along the conduit so as to discriminate the location along the conduit of the acoustic sources of said acoustic signals
Data Source
AI summary
This application relates to methods and apparatus for monitoring of conduits, especially oil or gas pipelines, as an object such as pipeline pig moves within the conduit. The method comprises monitoring at least part of a conduit(206) using a fibre optic(202) distributed acoustic sensor (204) as the object (208) passes along the conduit. The acoustic signals detected from at least one sensing location (203) as the object moves along the conduit are analysed so as to discriminate acoustic signals received at said sensing location from different locations. The method allows the contributions to the acoustic signal at a given sensing portion from different locations to be separately identified, and can allow the detection of the location of acoustic sources along the conduit even if the source is outside the section of conduit which is monitored. The method provides a method of leak detection that can extend the monitoring of the pipeline beyond the location of the optical fibre.