|Title||Use of geomagnetic data for evaluation of telluric effects on pipelines|
|Author||Trichtchenko, L; Fernberg, P; Harrison, M|
|Source||Proceedings of CORROSION 2010; 2010 p. 1-10|
|Links||Abstract - Résumé|
|Alt Series||Earth Sciences Sector, Contribution Series 20100385|
|Meeting||CORROSION 2010; San Antonio; US; March 14-18, 2010|
|Media||paper; on-line; digital|
|Subjects||geophysics; engineering geology; pipeline feasibility studies; pipelines; geomagnetic fields; geomagnetism; geomagnetic variations; magnetic disturbances; magnetic storms; magnetic field; models;
|Illustrations||profiles; location maps; plots|
|Program||Targeted Hazard Assessments in Northern Canada, Public Safety Geoscience|
|Abstract||Telluric currents interfere with cathodic protection systems and cause variations in pipe-to-soil potentials, which can exceed the levels recommended for protection of the pipeline steel. The amplitudes
of telluric currents observed in a pipeline depend on three factors: (1) the level of the geomagnetic activity, (2) conductivity of the underlying earth and (3) pipeline electromagnetic properties and geometric parameters. These factors have been
incorporated into mathematical models that are used to estimate the pipe-to-soil potential variations due to telluric activity.|
The time when pipe-to-soil potential variations exceed the recommended level can be different depending on the
different telluric activity at the pipeline locations. To evaluate this, a simple model for the telluric electric field has been set up, based on the geomagnetic data and an earth conductivity model. A statistical study based on the long records of
the geomagnetic data from Canadian magnetic observatories and conductivity structures of the deep earth allows evaluating telluric activity for 30 years period.
In order to show the geographical areas with different levels of activity, a set of
maps has been produced and is available through Atlas of Canada web page: http://atlas.nrcan.gc.ca/auth/english/maps/environment/naturalhazards/space weather.
The estimated telluric electric fields were used as an input to model pipe-to-soil
potential variations on a pipeline. In order to do this, the developed pipeline model has been incorporated to provide an on-line service for different users. The on-line service allows the user to evaluate the pipe-to-soil potential fluctuations at
a particular location for a user-defined pipeline.