Three-dimensional magnetotelluric modeling and inversion
Article Abstract:
Finite difference formulations of Maxwell's equations are used to solve forward 3-D modeling problems of subsurface geometry data obtained through magnetotelluric (MT) modeling. MT is the determination of the nature and distribution of subsurface rock through measurement of the apparent resistivity of the varied rock to a spectrum of natural, low-level electromagnetic radiation. A central problem of the MT process is obtaining a 3-D image of rock distributions. A critical step in validating a 3-D MT technology is developing a 'forward' model that will predict the electrical response of the varied mineral distributions to the electromagnetic radiation. The quality of interpretation of the measured MT data is vital to the development of a realistic model. Details of the development and validation of a 3-D model are described.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1989
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Comments on "Magnetotelluric Exploration for Hydrocarbons." (technical)
Article Abstract:
An earlier paper erred in stating that the worst case for an incident wave field is at glancing incidence (theta = pi/2). The plane wave spectrum for a source at some finite distance includes complex angles, the magnitude of which may be much greater than pi/2. The statement that it is sufficient to consider only normally incident waves is an oversimplification. The source dependence should be known when using the surface impedance technique. The author of the original paper has no disagreement with the points brought up and admits the lack of 'rigor' in several instances. He claims the paper was intended as a broad overview to a general audience, and he wanted to concentrate on practical implementations of the technique. He reiterates the importance of source dependence and of fiber in the diet.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1989
User Contributions:
Comment about this article or add new information about this topic:
Magnetotelluric exploration for hydrocarbons
Article Abstract:
Magnetotellurics (MTs) is a useful geophysical exploration method for locating hydrocarbon resources by determining rock electrical resistivity as a function of measurements of natural, low-level (0.0005-500Hz) electromagnetic frequencies in the subsurface. Rock types significant in hydrocarbon exploration must be thoroughly known to enable interpretation of signal impedances (as a function of apparent resistivity), as MT can not identify oil directly. Typically, the MT data acquired is used in conjunction with other methods for the assessment of subsurface hydrocarbon presence. Details of MT theory, practices, strengths and weaknesses are described. Several case histories of the use of MT in hydrocarbon exploration are briefly described.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1989
User Contributions:
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