Research On Optical Fiber Vibration Sensing Technology For Safety Monitoring Of Long-distance Oil Pipeline

Long-distance pipeline is one of the main modes of transportation of strategic resources such as oil and natural gas,and its safe operation and maintenance is very important.However,there are many problems such as oil stealing and pipeline leakage,which seriously endanger the safe operation of long distance pipeline,once a wide range of leakage or explosion accidents will cause huge economic losses and even serious environmental pollution,therefore,it is of great significance to carry out real-time monitoring of long distance pipeline.In this paper,the development of long distance petroleum pipeline and the research of pipeline safety monitoring are reviewed,and the existing pipeline monitoring technology is summarized.Due to the drilling of the pipeline and leakage phenomena can produce vibration signals,so we can use the pipeline vibration signals as the detection object,two method of vibration sensor based on fiber Bragg grating(FBG)and Fabry-Perot(FP)cavity vibration sensing based on fiber micro-cantilever are studied.The vibration sensing principle of FBG and FP cavity is analyzed,and the mechanical structure,signal acquisition and signal demodulation are analyzed and designed.The main contents of this thesis include:1.The research on the early warning technology of perforated oil stealing based on FBG vibration sensor is carried out,the real-time monitoring system of pipeline vibration signal is built,percussion and field drilling experiments with different diameters and different rotating speeds were carried out on the simulated pipelines.Partial least squares discriminant analysis(PLSDA)is used to identify different vibration signals on the pipeline.2.A simple vibration sensor based on fiber micro-cantilever beam is designed and fabricated,the feasibility of the scheme is analyzed theoretically.In the laboratory,the sensing system is used to detect the vibration signal,the processing of the cantilever beam,the vibration simulation of the cantilever beam,the encapsulation of the sensing head,the signal acquisition and demodulation are analyzed.The experimental results show that the method is feasible for the monitoring of the vibration signal.At the same time,construction of electronic microphone system to detect the pipeline vibration signal as a contrast experiment,the advantages and disadvantages of the two kinds of pipeline vibration detection methods are compared.The theoretical analysis and experimental results show that the vibration sensing based on FBG and vibration sensing scheme based on fiber micro-cantilever beam can detect the vibration signal of pipeline,compared with the traditional detection method,they have good sensitivity and high resolution.This paper provides a reference technical scheme for the monitoring of the destructive behavior of oil pipeline transportation.