The Detection Of Leakage And Location Based On The Distributed Fiber-Optic On Underwater Pipeline And Date Analysis Methods

The working environment of underwater pipeline is even worse than the pipeline on the land,it will lead to a higher rate of pipeline leakage accident.Pipeline storage and transportation of crude oil pipeline,petroleum,natural gas and other media.If the pipeline is leak it will not only causes the environmental pollution,and huge losses to the economy,but also a threat to the local people.In this paper,take the underwater oil and gas pipelines as a detection object,use the interferometric distributed optical fiber sensors and choose the applicable signal demodulation technology,to study the leakage detection and location and data analysis methods of the distributed optical fiber underwater pipeline.(1)Study the mixed interference principle based on Sagnac and Mach-Zehnder,according to the pattern of the leakage detection and the principle of location.Design the simulation equipment to detect the underwater pipeline leakage,to improve the experimental testing environments.Study the signal demodulation method of optical fiber interferometer.Analyze the mathematical model of PGC demodulation.Design the PGC demodulation circuit module and make it.(2)Based on the leakage detection methods and positioning technology of the underwater oil and gas pipeline.Do the experiments and analysis for the detection system in different experimental environment,different leakage points position,and different pipeline pressure.Propose the technology index of the pipeline leakage detection experimental system.And analyze the stability,the accuracy and the sensitivity of the system.(3)Since the traditional positioning method is not accurate,and the positioning error is large.So establish the regression model of the leakage sample which is based on the principle of SVM.Optimize the relevant parameters of the SVM based on the method of the grid search method and PSO.Analyze the corrected samples of the leakage points.After optimization of grid search method,the average absolute error of experimental samples is 118.85 m,and the error is reduced by 30 m.By optimizingparameters of PSO,the error is reduced by 79.7m,and improve the positioning accuracy.(4)In the experiments,the leakage detection can detect the leakage hole which is more than 2.5 mm.The length of the pipeline in the experiments is 1.3m.Meanwhile,its outer diameter is 40 mm,its wall thickness is 3 mm,and the pressure in the pipeline is more than 0.2 MPa.Besides,propose the ways to improve the detection system performance and positioning accuracy,and solve the optimization of the underwater pipeline detection system.