The Research On Integrity Evaluation Method Of Oil And Gas Pipeline Based On Distributed Optical Fiber Sensor

Through more than 150 years of development in modern pipeline transportation industry,by twenty-first Century,pipeline transportation has become one of the five major means of transportation including highway,railway,aviation and water transportation.It has become an important pillar of economic development.With the expansion of the pipeline network,the pipeline network is becoming more and more complex.At the same time,the working hours of the pipeline are growing,and the leakage and destruction of the pipeline due to its own aging,human destruction and natural factors are often seen.Due to the special conveying mode of the high pressure,once the pipeline is damaged,there will be a risk of explosion and a threat to the safety of people's lives and property.Therefore,the research of pipeline health inspection technology and integrity evaluation method is of great practical significance.According to the special laying environment of pipes,combined with the advantages of distributed optical fiber sensors.In this paper,the evaluation method of pipeline integrity based on distributed optical fiber technology is studied,and the structure state evaluation method and leakage detection method of pipeline are studied respectively.The distributed temperature measurement technology based on Fiber Raman scattering(DTS)can monitor the anomaly of the temperature field caused by the leakage of the pipeline,thus realize the identification of the leakage of the pipeline,and become an effective technique for the leakage monitoring of the oil and gas pipeline.This technology does not need to fix the sensor on the pipe,which is simple and convenient for construction.Based on the brief introduction of the principle of pipeline leakage monitoring based on DTS,a test system for leakage monitoring of buried pipelines is designed.Through the test simulation of the leakage of the foot size oil pipeline,the influence of the internal medium temperature,leakage flow,the damage degree of the insulation layer and the position of the sensor on the leakage identification is studied.The method of pipeline leakage identification based on DTS real-time monitoring data is proposed,and the test data are analyzed in depth.Based on the "outlier" concept and linear regression analysis method in mathematical statistics and analysis,the test data are further processed,and the leakage index setting is made according to the test data.The leakage judgment and location are more comprehensive and accurate.In this paper,a monitoring scheme of buried pipeline based on distributed optical fiber sensor is proposed,and a quantitative evaluation method for the structure state of buried pipeline based on distributed monitoring data is established.In the actual project,a monitoring scheme based on distributed optical fiber sensor is designed and implemented,which is seamless connecting with the buried pipeline construction technology.The distributed optical fiber sensor can accurately obtain the time and space evolution behavior of the bending strain and temperature of buried pipeline,overcome the limitation that the common point sensor can not cover the whole pipe,and can evaluate the structure state of the buried pipeline in real time and quantitatively.This method can provide a basis for evaluating the life cycle structure of buried pipelines.The pipeline monitoring scheme,leakage identification method and structure state evaluation method proposed in this paper have very positive significance for the evaluation of the state of the pipeline operation and the detection and positioning after the leakage.