Parallel Simulation of Audio- and Radio-Magnetotelluric Data

This paper presents a novel numerical method for simulation controlled-source audio-magnetotellurics (CSAMT) and radio-magnetotellurics (CSRMT) data. These methods are widely used in mineral exploration. Interpretation of the CSAMT and CSRMT data collected over an area with the complex geology requires application of effective methods of numerical modeling capable to represent the geoelectrical model of a deposit well. In this paper, we considered an approach to 3D electromagnetic (EM) modeling based on new types of preconditioned iterative solvers for finite-difference (FD) EM simulation. The first preconditioner used fast direct inversion of the layered Earth FD matrix (Green’s function preconditioner). The other combined the first with a contraction operator transformation. To illustrate the effectiveness of the developed numerical modeling methods, a 3D resistivity model of Aleksandrovka study area in Kaluga Region, Russia, was prepared based on drilling data, AMT, and a detailed CSRMT survey. We conducted parallel EM simulation of the full CSRMT survey. Our results indicated that the developed methods can be effectively used for modeling EM responses over a realistic complex geoelectrical model for a controlled source EM survey with hundreds of receiver stations. The contraction-operator preconditioner outperformed the Green’s function preconditioner by factor of 7–10, both with respect to run-time and iteration count, and even more at higher frequencies.

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Mineral exploration with 3-D controlled-source electromagnetic method: a synthetic study of Sukhoi Log gold deposit

Geophysical Journal International ◽

10.1093/gji/ggz390 ◽

2019 ◽

Vol 219 (3) ◽

pp. 1698-1716 ◽

Cited By ~ 3

Author(s):

M Malovichko ◽

A V Tarasov ◽

N Yavich ◽

M S Zhdanov

Keyword(s):

Finite Difference ◽

Gold Deposit ◽

Large Scale ◽

Mineral Exploration ◽

Mineral Deposit ◽

Hydrocarbon Exploration ◽

Contraction Operator ◽

Inversion Algorithm ◽

Controlled Source ◽

Regularized Inversion

SUMMARY This paper presents a feasibility study of using the controlled-source frequency-domain electromagnetic (CSEM) method in mineral exploration. The method has been widely applied for offshore hydrocarbon exploration; however, nowadays this method is rarely used on land. In order to conduct this study, we have developed a fully parallelized forward modelling finite-difference (FD) code based on the iterative solver with contraction-operator preconditioner. The regularized inversion algorithm uses the Gauss–Newton method to minimize the Tikhonov parametric functional with the Laplacian-type stabilizer. A 3-D parallel inversion code, based on the iterative finite-difference solver with the contraction-operator preconditioner, has been evaluated for the solution of the large-scale inverse problems. Using the computer simulation for a synthetic model of Sukhoi Log gold deposit, we have compared the CSEM method with the conventional direct current sounding and the CSEM survey with a single remote transmitter. Our results suggest that, a properly designed electromagnetic survey together with modern 3-D inversion could provide detailed information about the geoelectrical structure of the mineral deposit.

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Relationship of the self‐potential Green’s function to solutions of controlled source direct‐current potential problems

Geophysics ◽

10.1190/1.1440945 ◽

1979 ◽

Vol 44 (11) ◽

pp. 1879-1881 ◽

Cited By ~ 5

Author(s):

David V. Fitterman

Keyword(s):

Green’S Function ◽

Green's Function ◽

Direct Current ◽

Streaming Potential ◽

The Self ◽

Simple Relationship ◽

Controlled Source ◽

Source Mechanisms ◽

Vertical Contact ◽

Self Potential

This note presents a simple relationship between the self‐potential (SP) Green’s function and the solution of the controlled‐source direct‐current (dc) potential problem which allows a simplified means of determining the SP Green’s function. An example of its application to the vertical contact problem will be presented. The case of a streaming potential source mechanism will be considered, although any of the SP source mechanisms described by Nourbehecht (1963) could be substituted.

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Interferometric correlogram-space analysis

Geophysics ◽

10.1190/1.3519875 ◽

2011 ◽

Vol 76 (1) ◽

pp. SA9-SA17 ◽

Cited By ~ 8

Author(s):

Oleg V. Poliannikov ◽

Mark E. Willis

Keyword(s):

Green’S Function ◽

Green's Function ◽

The Other ◽

Seismic Interferometry ◽

Controlled Source ◽

Space Analysis

Controlled-source seismic interferometry is a method of obtaining a virtual shot gather from a collection of physical shot gathers. The set of traces corresponding to two common receiver gathers from many physical shots is used to synthesize a virtual shot located at one of the receivers and a receiver at the other. An estimate of the Green’s function between these two receivers is obtained by first crosscorrelating corresponding pairs of traces from each of the shots and then stacking the resulting crosscorrelograms. We studied the structure of crosscorrelograms obtained from a VSP acquisition geometry using surface sources and downhole receivers. The model is purely acoustic and contains flat or dipping layers and/or point inclusions that act as diffractors. We propose a semblance analysis based on moveout curves for both point diffractors and flat or dipping layers, which can be used to improve the quality of redatumed traces either by rejecting certain events prior to stacking or by enhancing them.

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