Mechanism of earth eddy current in North China and its effect on pipeline pipe-soil potential

The specific electrical structure around the homogeneous earth can generate eddy current in this homogeneous geology. In this paper, the equivalent current source is inverted from the data of several geomagnetic stations and the geoelectric model is constructed according to the actual topography. The research explores the influence caused by equivalent current and electrical structure on eddy current characteristics where the eddy current exists, and the mechanism of eddy current generation and eddy current movement in the specific area is revealed. Finally the distribution characteristics of pipe-soil potential (PSP) of oil pipelines laid in the area are calculated. The consistency between the calculated PSP and the observed PSP shows that the eddy can aggravate the influence of geomagnetic disturbance on the pipeline. (authors)