Specification of geomagnetically induced electric fields and currents in pipelines

Abstract

Variations of the Earth's magnetic field induce electric fields in pipelines. These induced electric fields drive electric currents along the pipelines that can interfere with the cathodic protection systems installed to prevent corrosion of the pipelines. For design of systems to counteract these effects it is necessary to be able to calculate the size of the currents that will be produced by different geomagnetic conditions. In this study we present the results of numerical modeling of the induced electric fields and currents produced in a long, coated pipeline buried in the Earth. We investigate the effects of the frequency dependence for the electric field and current in the pipe. Calculations are made for different frequencies of the source fields in two extremum cases, E and H polarizations of the incident geoelectromagnetic field. It is shown that at low frequencies (<0.01 Hz) the effects of frequency dependence on electric fields and currents in the pipe are negligible but that they should be taken into account at higher frequencies (1 Hz). Copyright 2001 by the American Geophysical Union.