Fast approximate solutions of transient electromagnetic response to a target buried beneath a conductive overburden

Guimin Liu, Michael Asten

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Abstract

Here we derive fast transient electromagnetic (TEM) solutions for the simplified model of a thin-plate conductive target buried in a resistive host rock overlain by a thin conductive overburden. For this model, the total TEM field is composed of the overburden response, which is known analytically, and the target response which is derived approximately here. In the derivation, the target is represented using a wire loop and the transient response of the target in free space is thus approximated with a single exponential function. The primary electromagnetic interaction between the target and the overburden is accounted for in the computation of the current in the target loop by the convolution of the overburden-delayed driving field with the exponential function. For a first-order approximation, the target response can be computed from the target loop current by the Biot-Savart law as if the target is in freespace, neglecting the second overburden-delay effect. The second-order approximation that accounts for the second overburden-delay effect does not yield significantly improved results. The approximate solutions agree reasonably well with scale model and numerical results published in the geophysical literature. Because the approximate solutions are given in simple analytical forms, their computation is more than 100 times faster than conventional methods and can be easily done on a personal computer.

Original languageEnglish
Title of host publication1992 SEG Annual Meeting
Subtitle of host publication1992 Society of Exploration Geophysicists Annual Meeting; New Orleans; United States; 25 October 1992 through 29 October 1992
Pages481-483
Number of pages3
Publication statusPublished - 1 Jan 1992
Externally publishedYes
Event1992 Society of Exploration Geophysicists Annual Meeting - New Orleans, United States of America
Duration: 25 Oct 199229 Oct 1992

Conference

Conference1992 Society of Exploration Geophysicists Annual Meeting
CountryUnited States of America
CityNew Orleans
Period25/10/9229/10/92

Cite this

Liu, G., & Asten, M. (1992). Fast approximate solutions of transient electromagnetic response to a target buried beneath a conductive overburden. In 1992 SEG Annual Meeting: 1992 Society of Exploration Geophysicists Annual Meeting; New Orleans; United States; 25 October 1992 through 29 October 1992 (pp. 481-483)