Electromagnetic response of a buried cylindrical conductor for sheet and line current sources

Ogunade, S. O.

doi:10.1007/bf00879433

Cited by 5 publications

(2 citation statements)

References 7 publications

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“…The electromagnetic (EM) response of buried line conductors such as cables and pipelines has attracted attention from the EM community for more than a decade (Wynn & Zonge 1975;Campbell 1977Campbell ,1978Campbell ,1980Campbell & Zimmermann 1980;Ogunade 1981Ogunade , 1982Chen, Xu & Yang 1991;Zhang & Luo 1991). Indeed, buried cables and pipelines are among the most common cultural conductors G encountered in E M exploration programs (Nekut & Eaton 1990).…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic modelling of buried line conductors using an integral equation

Qian

Boerner

1995

Geophysical Journal International

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S U M M A R YAn integral equation is derived to represent the electromagnetic response of line conductors buried below the surface of a horizontally stratified earth. By permitting several finite-length line conductors of arbitrary topology, this representation is free of the limitations imposed by analytic solutions. The integral equation is formulated in terms of excess electric current (scattering current) flowing along the line conductor and is solved numerically by dividing the line conductor into many small segments. In general, the excess electric current is controlled by both the internal and external impedance of the line conductor. The internal impedance is the longitudinal resistance of the line conductor. The exterpal impedance is caused by galvanic and inductive coupling between the line conductor and its local environment. The galvanic resistance to current channelling is spatially variable with a minimum in the centre of a uniform line conductor and is determined by conductor geometry and the host conductivity structure. The inductive external impedance is proportional to frequency and quadrature dominant. It is a function of lineconductor geometry, cross-section and burial environment. The inductive impedance effectively reduces the spatial dependence of the external impedance at high frequency by presenting a large reactance (which is uniform at all points along the conductor) to the exciting electric field.Within the quasi-static limit (i.e. where displacement current can be neglected), electromagnetic excitation by either horizontal electric or vertical magnetic dipoles produces a constant primary electric field at high frequencies (far field). The excess electric current in the line conductor will always be inversely proportional to frequency for these types of sources at sufficiently high frequencies where the inductive external impedance is dominant. Horizontal magnetic dipole and vertical electric dipole sources generate primary electric fields that are proportional to the square root of frequency in the high-frequency limit of the quasi-static domain and the excess electric current excited by such sources will decrease as the inverse of the square root of frequency.

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Section: Introductionmentioning

confidence: 99%

Electromagnetic modelling of buried line conductors using an integral equation

Qian

Boerner

1995

Geophysical Journal International

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“…It is in the light of these facts and observation that the assumption made by ONI and AGUNLOYE (1976) that a coupling between the equatorial electrojet and outer space would result in the presence of a secondary inducing source field in a region between 180 to 350km above the earth's surface, is being examined. This assumption resulted from their study of the induction effect at The finite difference model used in this study has been previously described by OGUNADE (1982). The relevant equations which give the electric and magnetic fields at the surface of a layered earth are obtainable from the elementary magnetic fields as starting or initial values.…”

Section: Introductionmentioning

confidence: 99%

A perspective of the induction studies in south western Nigeria.

Ogunade

1983

J. geomagn. geoelec

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Employing the finite difference technique the concept of a secondary inducing source field at an altitude between 180 to 350km in south western Nigeria has been examined. The study compared numerical results with field results obtained by ONI and AGUNLOYE (1976) at Ibadan, Okitipupa and Igbanke. At both Ibadan and Okitipupa the numerical results tend to support the presence of a secondary inducing source field at 210km and 320km respectively, while the secondary inducing source height at Igbanke was found to be closer to that of the equatorial electrojet.

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Induced fields due to a buried conducting cylinder excited by arbitrarily located localized source fields

Ogunade¹

1984

Physics of the Earth and Planetary Interiors

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Electromagnetic response of a buried cylindrical conductor for sheet and line current sources

Cited by 5 publications

References 7 publications

Electromagnetic modelling of buried line conductors using an integral equation

Electromagnetic modelling of buried line conductors using an integral equation

A perspective of the induction studies in south western Nigeria.

Induced fields due to a buried conducting cylinder excited by arbitrarily located localized source fields

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