Study On Key Technology And System Development Of Oil And Gas Pipeline Stress Monitoring

With the vigorous development of China’s oil and gas industry,as one of the most important methods of oil and gas transportation,the safe operation of pipelines is of self-evident significance.However,pipeline accidents caused by environmental or human factors occur frequently,which seriously threaten the safety of people’s life and property.In view of the need to grasp the operating status of oil and gas pipelines in time to prevent pipeline accidents,this paper studies the key technology of online stress monitoring of oil and gas pipelines,develops a new type of vibrating wire dual-coil strain sensor,and proposes a new monitoring and early warning system.The study contents mainly include:(1)Theoretical analysis of vibrating wire strain sensor and monitoring and early warning.Based on the theory,the theoretical model,working principle,excitation mode,vibration pickup principle and mode of the vibrating wire strain sensor are analyzed.Combined with the pipeline site and mechanics theory,the composition of the axial stress of the pipeline and the causes of each stress are analyzed.And according to the standard specification,an early warning model of the stress state of oil and gas pipelines is proposed.(2)Simulation analysis and development of vibrating wire strain sensor.Through the modal simulation of the vibrating wire,the influence of the length and wire diameter of the vibrating wire on its natural frequency is analyzed,and the correctness of the basic theory of the vibrating wire is verified.The simulation model of the vibrating wire sensor was established based on COMSOL finite element software,and the effects of the excitation current,the number of coil turns,the size of the magnet static magnetic field and the load on the resonance signal of the vibrating wire sensor in the simulation model were studied.The results show that the resonance waveform of the sensor changes regularly with each influencing factor.On the basis of the sensor simulation analysis and combined with the actual situation,a new type of vibrating wire double-coil strain sensor is developed.(3)Study on testing and testing of vibrating wire strain sensor.The detection signal of the vibrating wire sensor is analyzed,and the influence of the load on its resonance signal is explored from the time domain and frequency domain respectively.The load and temperature test of the vibrating wire sensor is studied,and the influence of the two on the detection performance is analyzed combined with the sensor theory.The results show that the applied load has a positive correlation with the natural frequency of the vibrating wire sensor,the natural frequency has a quadratic polynomial fitting relationship with the microstrain,and the modulus has a linear relationship with the microstrain,the fitting results of the temperature and the microstrain have a linear positive correlation.The test results show that the vibrating wire sensor has good detection performance.(4)Design and development of oil and gas pipeline stress monitoring and early warning system.According to the requirements of obtaining the stress state of oil and gas pipelines,a stress monitoring and early warning system for oil and gas pipelines is developed based on Lab VIEW platform.The designed monitoring system is tested on site.The test results show that the system can obtain pipeline monitoring data stably and accurately in real time.Combined with the oil and gas pipeline strain monitoring and early warning model,the pipeline status and early warning level can be more accurately evaluated.In addition,a pipeline early warning state discrimination method based on BPNN is proposed,which can accurately predict the percentage of pipeline strain state according to the real-time monitoring data of the system,and realize the judgment of pipeline risk level.