Studying the TEM response of a 3-D conductor at a geological contact using the FDTD method

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Geophysics

DOI:https://doi.org/10.1190/1.1443859· OSTI ID:100757

Wang, T; Tripp, A C; Hohmann, G W ^[1]

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1. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Geology and Geophysics

Many mineral targets are located near contact zones. Since the change of resistivity across the contact can distort or obscure the transient electromagnetic (TEM) response of the target, it is important to understand the possible effects. Previous investigators have examined similar problems using scale models. For example, Spies and Parker (1984) studied the TEM responses of fixed-loop and moving-loop configurations to geological contacts with lateral resistivity variations. More recently, Wilt (1991) systematically studied TEM soundings near a geological contact and observed that different survey systems respond to the contact in different ways. This paper will illustrate the use of the finite-difference, time-domain (FDTD) algorithm of Wang and Hohmann (1993) for calculating the TEM response of a 3-D conductive body at a geological contact. The algorithm is based on the Yee staggered grid FDTD method for solving the transient electrical nonmagnetic field responses of a 3-D model. On a suitable computer, a wide range of model responses can be readily calculated, a versatility that scale modeling does not share. This study uses a fixed transmitter loop, roving-receiver configuration. Many other configurations can be regarded as special cases of this survey. It is commonly employed, for instance, by the Newmont EMP (Body and Wiles, 1984), UTEM (West et al., 1984), and Geonics EM37 systems. The configuration also facilitates finite-difference, time-domain modeling because it does not require frequent movement of the source.

• OSTI ID: 100757
• Journal Information: Geophysics, Journal Name: Geophysics Journal Issue: 4 Vol. 60; ISSN GPYSA7; ISSN 0016-8033
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
58 GEOSCIENCES
ALGORITHMS
DATA PROCESSING
ELECTROMAGNETIC SURVEYS
GEOLOGIC DEPOSITS
GEOTHERMAL SYSTEMS
MINERALIZATION