Study On The Mechanism Of Earth Eddy Current And Its Effect On Pipeline

There are several PSP anomalies in the Gas Pipeline,especially when the geomagnetic disturbance occurs,the PSP anomalies of the pipeline are the most severe.This phenomenon affects the life of the pipeline,but also interferes with the normal operation of the pipeline.Based on the analysis of monitoring data of geomagnetic stations,this paper studies and calculates various situations of PSP anomaly during geomagnetic interference.It is proposed that the PSP anomaly of the Eastern Pipeline of Westto East Gas Pipeline is due to the existence of eddy current on the earth surface of North China,and the eddy current intensifies the influence of geomagnetic disturbance on the pipeline.The local electric field is calculated according to the original geomagnetic data of geomagnetic stations and the three-dimensional geoelectric structure of the earth.Then the PSP method for calculating the surface of geoelectric structures is presented.Based on the geoelectric data of the North China Plain,a three-dimensional geoelectric conductivity model of the North China Plain is established,and the equivalent current source at high altitude is constructed by using the geomagnetic H of the Beijing geomagnetic station on November 06,2016.The current source is applied to the three-dimensional earth conductivity model,and the formation mechanism of the eddy current and the factors affecting the eddy current are revealed by simulation.By calculating the electric field along the Rizhao-Dongming section,which is close to Eastern Pipeline of Westto East Gas Pipeline,the spatial PSP and the time-domain PSP along the pipeline are calculated.Through the analysis and comparison of the theoretical calculation,it is revealed that the pipeline is seriously affected by the eddy current,and the influence of the eddy current on the PSP of the pipeline when the geomagnetic disturbance occurs is explained.In this paper,a three-dimensional geoelectric conductivity model of the eastern Songnen Plain is constructed based on the electrical data of the area.By analyzing the frequency and azimuth of the equivalent current source,the results that the surface eddy current is affected by the frequency and azimuth of the air current source are given.By changing the conductivity structure of the area,the region is illustrated.The mechanism of eddy current in the domain.The air equivalent current source is constructed by using the data H of the geomagnetic station on November 10,2016.The PSP along the time and space distribution of Qingling pipeline is obtained by applying the three-dimensional geoconductivity model in this area.The reasons for the PSP anomaly in the area of eddy current are analyzed.In this paper,it is found that a specific geological structure can form a stable eddy current on the surface of the earth,and the influence of the change of the equivalent current source at high altitude and the ground conductivity on the movement and accumulation direction of the surface eddy is analyzed.The effect of eddy current on the PSP of pipeline is obtained by analyzing the PSP of pipeline in the eddy region and the PSP of time-domain variation.It shows that the reason of PSP abnormality of pipeline in the eddy region is probably due to the effect of the eddy current formed on the pipeline at the surface.