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The Analysis Of Distributed Optical Fiber Monitoring Pipeline In The State Method

Posted on:2016-05-30Degree:MasterType:Thesis
Country:ChinaCandidate:X ZhangFull Text:PDF
GTID:2191330461977783Subject:Water conservancy project
Abstract/Summary:PDF Full Text Request
The operation safe of oil and gas pipelines has always been the focus of the people. By the analysis of domestic and international long-distance pipeline failure accident, we find that the lateral buckling damage and the subsidence damage account for a large proportion of pipeline damage. It is seriously harm to the safe operation of the pipeline, so the research of the lateral buckling damage and the subsidence damage is particularly important. This paper describes a distributed optical fiber monitoring system, based on Brillouin scattering theory. The system has many advantages in monitoring pipeline operation, which can realize a long distance, real-time, distributed monitoring. The main work includes the following aspects:(1)The exploration of laying program of distributed optical fiber. Pipe bending may exist in either one direction, then the neutral axis of pipe section is on uncertain position, resulting the strain at the point of maximum deformation is likely to not be monitored by laying one fiber sense. Based on the monitoring principle of this paper develops a rational layout-fiber plan:along pipeline lay three parallel angled fiber, which can be used to solve the maximum strain,considering pipeline may happen deformation in any direction.(2)The research of continuous pipeline buckling based on distributed optical fiber monitoring. In the measurement, select bare fiber as the sensing fiber, which has a higher measurement accuracy. Then use the pipeline buckling theory and separate bending strain and axial compressive strain from the collected strain. Through the bending strain diagram, we can find the evolution of the pipeline buckling. The development trend of strain collected by RST311L Laser Station and BOTDA coincides, which can prove the feasibility of optical fiber monitoring pipeline buckling.(3)The analysis of the subsidence of segments pipeline based on distributed optical fiber monitoring. Under normal circumstances, there is no significant change of the strain of pipeline body. And once subsidence and other geological disasters occur, the strain of pipeline will change obviously and suddenly. This phenomenon can be monitored by the optical fiber sensor. Through the subsidence experiments of the two-socket-type buried pipeline, we can find the model of pipe stress changes from simply supported beam structure to cantilever structure due to the different ranges of subsidence, and the pipeline joints mainly transfer shear.(4)The study of numerical modeling of the segments buried pipeline. The ANSYS modeling process mainly analysis the subsidence experiments of segments pipeline, and compared with the results of optical monitoring, indicating the feasibility of optical fiber monitoring. Meanwhile, we studied the material parameters of pipeline joints and found the pipeline deformation determines the axial displacement, angle and the value of shear at the pipeline joints. Therefore, when selecting interface connecting material, be sure the material have a certain deformation capacity to accommodate the deformation at the interface.
Keywords/Search Tags:lateral buckling damage, subsidence damage, fiber monitoring, BOTDA, ANSYS analysis
PDF Full Text Request
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