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Focused resolution of thin conducting layers by various dipole EM systems

Saurabh Kumar Verma and S. P. Sharma
Focused resolution of thin conducting layers by various dipole EM systems
Geophysics (April 1995) 60 (2): 381-389


Electromagnetic sounding in the frequency domain can be performed in two ways--either by changing frequency at a location (frequency sounding) or by changing the transmitter-receiver (T-R) separation using a fixed frequency (geometric sounding). These changes in frequency or separation parameters effect vertical scanning of conductivity distributions below the earth's surface. In case of thin conducting layers, there could be an optimum range of frequencies or T-R separations that provide maximum resolution of the layer parameters. Thus, for a given buried target layer, it should be possible to find ranges of frequencies or separations that yield the best focusing. The present study deals with the focused resolution of a thin conducting layer in frequency sounding with variable T-R separation for four different dipole configurations.It is observed from the inversion of the data from various dipole electromagnetic (EM) systems that different T-R separations have different resolutions for the same target layer. It is also observed that for a particular loop system, the best resolution is observed at an optimum T-R separation. The resolution becomes poorer when the T-R separation is either increased or decreased from this particular separation. Thus it has been possible to propose a 'zone of focusing' for various dipole EM configurations. The study reveals that this zone is broadest for the horizontal coplanar loops system, implying that this system yields good resolution over a wide range of T-R separations. Compared to this, the perpendicular loops system yields a very sharp peak implying that it resolves the target over a very narrow range of separations. However, the perpendicular loops system provides resolution most parsimoniously requiring the least T-R separation. This is followed by the vertical coplanar, vertical coaxial, and horizontal coplanar loops systems.

ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 60
Serial Issue: 2
Title: Focused resolution of thin conducting layers by various dipole EM systems
Affiliation: National Geophysical Research Institute, Hyderabad, India
Pages: 381-389
Published: 199504
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 23
Accession Number: 1995-032929
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Secondary Affiliation: Rajasthan Ground Water Department, IND, India
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 199512
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