The Effect of Tidal Geoelectric Fields on GIC and PSP in Buried Pipelines

Compared with the investigation of geomagnetically induced currents (GIC) in power grids, there is less study about the effect of geomagnetic disturbance (GMD) on buried oil and gas pipelines in mid-low latitude areas, which includes GIC and pipe-to-soil potentials (PSP) effects. Therefore, it is of great significance to research the GMD effect in the mid-low latitudes. For this purpose, we performed the observation experiments on GMD influencing the GIC and PSP in China’s oil and gas pipelines. The data of GIC and PSP in the pipelines are obtained, which do not pertain to the characteristics of the geomagnetic storms caused by solar activity, as well as the GIC and PSP monitoring data deriving from geomagnetic storm on May 21, 2016. By analyzing the characteristics of waveform, frequency and phase of the geoelectric fields data from Lingyang Geomagnetic Observatory ( $35^{\circ } 32^\prime \text{N}$ , $118^{\circ } 52^\prime \text{E}$ ) 60 km away in northeast from the pipeline observation site, the study corroborated that GIC and PSP variations are driven by tidal geoelectric fields (TGF) during the geomagnetic quiet days in this paper. The mechanism of GIC generated by tidal geoelectric field is analyzed. Likewise, an analysis of GMD data from the Maling Mountain Geomagnetic Observatory ( $34^{\circ } 42^\prime \text{N}$ , $118^{\circ } 27^\prime \text{E}$ ), the GIC and the PSP have been done, it is illustrated that the GIC and PSP effects are caused by TGF and geomagnetic storm induced geoelectric field together during a geomagnetic storm. The results demonstrated that, near large areas of water, the effect of tidal geoelectric field on pipeline corrosion is persistent and serious. TGF impacts the calculation accuracy of GIC in pipelines and PSP. Therefore, we should account for the errors caused by TGF when calculating GIC and PSP in pipelines near seashores and a large body of water.