Project Description
Intrinsically safe sensing of structural response is one of the important challenges for condition monitoring of long-distance oil and gas pipelines. The distributed acoustic sensing (DAS) using coherent Rayleigh backscattering in an optical fibre offers an attractive technique to meet this challenge. In this project, DAS technique is applied to measure the distributed vibration of a laboratory pipeline, which can be subject to the excitation of unsteady flow, operating pump and motor, and impact hammer. By attaching strain-sensitive optic fibre cables to the pipeline, the Distributed Acoustic Sensing (DAS) technique measures the strain rate along the optic fibre as an indication of the dynamic response of the pipeline to external impact and flow excitation, allowing real-time and global monitoring of the health status of the pipeline.
The results by DAS are compared with that sensed by accelerometers. The focus of this comparative study was to understand the sensitivity of the DAS to spatial variations in the pipeline vibration, the relevance of DAS results to the radial response determined by accelerometers, the effect of attachment conditions on DAS, and the accuracy in determining the location of an impact force by DAS.
The final results were promising, with signs that DAS is capable of indicating dynamic stress distribution along the pipeline from the distributed vibration measured, as well as being capable of detecting the location of external impacts and possible failure of supports in the pipeline
