Modelling of geomagnetic induction in pipelines

Abstract

Abstract. Geomagnetic field variations induce telluric currents in pipelines, which modify the electrochemical conditions at the pipe/soil interface, possibly contributing to corrosion of the pipeline steel. Modelling of geomagnetic induction in pipelines can be accomplished by combining several techniques. Starting with geomagnetic field data, the geoelectric fields in the absence of the pipeline were calculated using the surface impedance derived from a layeredEarth conductivity model. The influence of the pipeline on the electric fields was then examined using an infinitely long cylinder (ILC) model. Pipe-to-soil potentials produced by the electric field induced in the pipeline were calculated using a distributed source transmission line (DSTL) model. The geomagnetic induction process is frequency dependent; therefore, the calculations are best performed in the frequency domain, using a Fourier transform to go from the original time domain magnetic data, and an inverse Fourier transform at the end of the process, to obtain the pipe-tosoil potential variation in the time domain. Examples of the model calculations are presented and compared to observations made on a long pipeline in the auroral zone.

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“…Similar studies have also been conducted in the Tierra del Fuego region of South America [Osella et al, 1998;Osella and Favetto, 2000]. Large GICs have been correlated with the largest rate of change of the geomagnetic field [Viljanen, 1997;Viljanen et al, 1999;Trichtchenko and Boteler, 2004] and simulations of PSPs on Canadian and Scandinavian pipelines have also been conducted [Boteler and Seager, 1998;Pulkkinen et al, 2001b;Trichtchenko and Boteler, 2002;Fernberg et al, 2007]. GIC signals observed on low-latitude pipelines [Martin, 1993;Waters et al, 2006] are likely to have different ionospheric source fields to those observed on high-latitude pipelines and provide additional spectral information for comparison with model predictions.…”

“…At high latitudes the Birkeland current system produces large deviations in the geomagnetic field, particularly during disturbed periods. In Finland and Canada, a number of studies have examined GICs and their effects on power transmission lines and oil pipelines [Campbell, 1978[Campbell, , 1986Viljanen andPirjola, 1994a, 1994b;Pulkkinen et al, 2001a;Trichtchenko and Boteler, 2002;Pirjola, 2005;Pulkkinen et al, 2008]. Similar studies have also been conducted in the Tierra del Fuego region of South America [Osella et al, 1998;Osella and Favetto, 2000].…”

“…For an N-layer Earth conductivity model, the orthogonal geoelectric and geomagnetic field components are related using a frequency-dependent surface impedance [Trichtchenko and Boteler, 2002] given by…”

“…[19] Determination of the geoelectric field from the geomagnetic field data have been performed in both the time domain [Pirjola, 2002;Hejda and Bochnicek, 2005] and the frequency domain [Pirjola, 1982[Pirjola, , 2002Trichtchenko and Boteler, 2002]. In the frequency domain, the simplest model assumes the Earth is a uniformly conducting half-space and the magnetic source field can be represented by a vertically downward propagating plane wave.…”

“…The first step is to determine the geoelectric field and the next step involves applying the calculated geoelectric field to the engineering problem for the appropriate infrastructure. The geoelectric field has been applied to the calculation of GICs in power networks using Kirchhoff's current laws [Viljanen and Pirjola, 1994a] and Complex Image methods Viljanen et al, 1999], and to the calculation of PSPs using Distributed Source Transmission Line (DSTL) theory [Boteler and Seager, 1998;Boteler, 2000;Pulkkinen et al, 2001b;Trichtchenko and Boteler, 2002].…”