Electromagnetic inversion using quasi‐linear approximation

Zhdanov, Michael S.; Fang, Sheng; Hursán, Gábor

doi:10.1190/1.1444839

Cited by 84 publications

(35 citation statements)

References 13 publications

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“…(1) It requires a fast, accurate and reliable forward 3-D problem solution. Approximate forward solutions (Zhdanov et al, 2000;Torres-Verdin and Habashy, 2002;Tseng et al, 2003;Zhang, 2003; among others) may deliver a rapid solution of the inverse problem (especially, for models with low conductivity contrasts), but the general reliability and accuracy of this solution are still open to question. (2) The inverse problem is large-scale; usually with thousands of data points (N) to be inverted in the tens of thousands of model parameters (M).…”

Section: Why Is It Numerically Tough?mentioning

confidence: 99%

Three-Dimensional Electromagnetic Modelling and Inversion from Theory to Application

Avdeev

2005

Surv Geophys

236

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The whole subject of three-dimensional (3-D) electromagnetic (EM) modelling and inversion has experienced a tremendous progress in the last decade. Accordingly there is an increased need for reviewing the recent, and not so recent, achievements in the field. In the first part of this review paper I consider the finite-difference, finite-element and integral equation approaches that are presently applied for the rigorous numerical solution of fully 3-D EM forward problems. I mention the merits and drawbacks of these approaches, and focus on the most essential aspects of numerical implementations, such as preconditioning and solving the resulting systems of linear equations. I refer to some of the most advanced, state-of-the-art, solvers that are today available for such important geophysical applications as induction logging, airborne and controlled-source EM, magnetotellurics, and global induction studies. Then, in the second part of the paper, I review some of the methods that are commonly used to solve 3-D EM inverse problems and analyse current implementations of the methods available. In particular, I also address the important aspects of nonlinear Newton-type optimisation techniques and computation of gradients and sensitivities associated with these problems.

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Section: Why Is It Numerically Tough?mentioning

confidence: 99%

Three-Dimensional Electromagnetic Modelling and Inversion from Theory to Application

Avdeev

2005

Surv Geophys

236

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“…Wannamaker et al (1984) and Anderson (1984) also greatly contributed to its development. In recent years, many people have put tremendous efforts into the improvement of the integral equation method (San Filipo and Hohmann, 1985;Newman and Hohmann, 1988;Wannamaker, 1991;Dmitriev and Nesmeyanova, 1992;Xiong, 1992;Xiong and Kirsch1 1992;Singer and Fainberg, 1997;Hursan and Zhdanov, 2002;Zhdanov et al, 2000;Zhdanov, 2002).…”

Section: Introductionmentioning

confidence: 98%

3D modeling and born approximation inversion for the borehole surface electromagnetic method

Wang

He²,

Wei

2007

Appl. Geophys.

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We present a 3D approach to numerical modeling of the borehole-surface electromagnetic (BSEM) method. The 3D electromagnetic response created by a vertical line current source in a layered medium is modeled using the 3D integral equation method. The modeling results are consistent with analytical solutions. 3D Born approximation inversion of BSEM data is also conducted for reservoir delineation. The inversion method is verified by a synthetic reservoir model.

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“…Consequently, the current state-of-the-art for magnetotelluric (MT) data interpretation is 3-D trial-and-error forward model fitting that is being used more frequently for hypothesis testing, and routine 3-D inversions are on the horizon (Mackie and Madden, 1993;Alumbaugh and Newman, 2000;Newman and Alumbaugh, 2000;Zhdanov et al 2000;Sasaki, 2001;Newman et al, 2002;Siripunvaraporn et al, 2005). Data acquisition on highly dense 2-D grids has been undertaken to study geothermal (e.g., Park and Torres-Verdin, 1988;Takasugi et al, 1992) and mining-scale problems (e.g., Zhang et al, 1998;Tournerie et al 2000), but regional-scale field experiments on a 2-D grid are often impractical due to high cost and inaccessibility.…”

Section: Introductionmentioning

confidence: 99%

2-D Versus 3-D Magnetotelluric Data Interpretation

Ledo

2005

Surv Geophys

103

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In recent years, the number of publications dealing with the mathematical and physical 3-D aspects of the magnetotelluric method has increased drastically. However, field experiments on a grid are often impractical and surveys are frequently restricted to single or widely separated profiles. So, in many cases we find ourselves with the following question: is the applicability of the 2-D hypothesis valid to extract geoelectric and geological information from real 3-D environments? The aim of this paper is to explore a few instructive but general situations to understand the basics of a 2-D interpretation of 3-D magnetotelluric data and to determine which data subset (TE-mode or TM-mode) is best for obtaining the electrical conductivity distribution of the subsurface using 2-D techniques. A review of the mathematical and physical fundamentals of the electromagnetic fields generated by a simple 3-D structure allows us to prioritise the choice of modes in a 2-D interpretation of responses influenced by 3-D structures. This analysis is corroborated by numerical results from synthetic models and by real data acquired by other authors. One important result of this analysis is that the mode most unaffected by 3-D effects depends on the position of the 3-D structure with respect to the regional 2-D strike direction. When the 3-D body is normal to the regional strike, the TE-mode is affected mainly by galvanic effects, while the TM-mode is affected by galvanic and inductive effects. In this case, a 2-D interpretation of the TM-mode is prone to error. When the 3-D body is parallel to the regional 2-D strike the TE-mode is affected by galvanic and inductive effects and the TM-mode is affected mainly by galvanic effects, making it more suitable for 2-D interpretation. In general, a wise 2-D interpretation of 3-D magnetotelluric data can be a guide to a reasonable geological interpretation.

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Electromagnetic inversion using quasi‐linear approximation

Cited by 84 publications

References 13 publications

Three-Dimensional Electromagnetic Modelling and Inversion from Theory to Application

Three-Dimensional Electromagnetic Modelling and Inversion from Theory to Application

3D modeling and born approximation inversion for the borehole surface electromagnetic method

2-D Versus 3-D Magnetotelluric Data Interpretation

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