Why use distributed sensing for critical pipeline monitoring
Distributed optical fibre sensing offers continuous pipeline monitoring at a spatial resolution not available using any other technology. Measurements of the ground temperature adjacent to the pipeline can provide an efficient and reliable method to monitor for leaks continuously in distance and time.
By simultaneously detecting the acoustic field in the same cable, external threats or seismic events to the integrity of the pipeline can be detected, identified and located before they breach the pipeline.
Strain measurements at all locations along the pipeline allow for early detection external stresses or movement whether from ground subsidence, the melting of permafrost, impacts from seismic events, or anthropogenic activities.
Alarms and alerts can be displayed on a proprietary user interface or output to central control systems.
How it works
Leak monitoring works by detecting a localised change of temperature at a point along the pipeline induced by a release of the contents in the pipeline into the surrounding soil. For liquids, such as oil, the measured change is usually a rise in temperature, whereas for high pressure gases there is a decrease in temperature due to the Joule-Thompson effect.
The heart of the leak detection system is the ULTIMA™ DTS distributed temperature sensor. The instrument continuously monitors the temperature at all points along a fibre optic cable. When a leak causes a change in temperature, the location of any leak can be pinpointed to within a few metres over many kms of pipeline.
Hotspot development can cause rapid and catastrophic failure, while external stresses can lead to pipeline displacement and ultimately breakage. Through continuous temperature monitoring using Silixa’s ULTIMA DTS, temperature can be monitored continually every 1 sec, allowing rapid operator response to developing hotspots.
By monitoring the strain at all points along the pipeline using Silixa’s DSS systems, movement that would lead to failure can be determined proactively, allowing mitigative measures to be taken before catastrophic failure occurs.
Event detection works by sensing the true acoustic field simultaneously at 1,000’s of points along the fibre optic cable as if it were a string of microphones then processing this data to recognise and locate the threats along the pipeline route.
The Silixa intelligent Distributed Acoustic sensor (iDAS™) operates by analysing the backscatter from an optical pulse which is launched into the fibre optic cable. The system can use this information to detect the event and determine its nature. By measuring the time between the laser pulse being launched and the signal being received the location along the pipeline can be calculated.