Research on Inversion Resolution for ERT Data and Applications for Mineral Exploration

Zhang, Gang; Zhang, Gui Bin; Chen, Chien Chih; Jia, Zheng

doi:10.3319/tao.2015.05.06.01(t)

Cited by 8 publications

(3 citation statements)

References 35 publications

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“…From this study's results, the inversion models with narrower electrode spacing tend to describe the complexity of the model better than the wider spacings. This is due to the greater number of model blocks in the models with short electrode spacing than those with larger electrode spacing, a finding consistent with the study of Zhang et al, [30]. Overall, the greater the mesh density, the higher the inversion resolution.…”

Section: Resistivity Models From Forward Modelingsupporting

confidence: 83%

Evaluation of the Proper Electrode Spacing for ERI Surveys in Open Dumpsites Using Forward Modeling

Chungam¹,

Vinitnantharat²,

Wangyao³

2022

Pol. J. Environ. Stud.

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Electrical resistivity imaging surveys are widely conducted in waste disposal sites due to their ease of operation and accurate results; however, some essential measurement parameters, such as optimal electrode spacing, have not been thoroughly evaluated. Accordingly, this study aims to identify the optimal electrode spacing for electrical resistivity surveys in open dumpsites. An electrical resistivity survey was conducted at the Nonthaburi disposal site, Thailand, and the results were compared to synthetic cases simulated using the forward modeling technique. Electrode spacing values of 2, 2.5, 4, and 5 m were used. The models were evaluated using the Nash-Sutcliffe model efficiency coefficient, model sensitivity, and root mean square error. The real case survey results illustrate that small electrode spacings of 2 and 2.5 m provide a realistic model, however, the root mean square error is higher due to the use of more outlier electrodes during measurement. Consistent with the synthetic case studies, electrode spacing values of 2 and 2.5 m yielded accurate inverted models. Overall, this study illustrates the benefits of using a forward modeling technique for selecting the optimal electrode spacing for open dumpsite surveys.

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Section: Resistivity Models From Forward Modelingsupporting

confidence: 83%

Evaluation of the Proper Electrode Spacing for ERI Surveys in Open Dumpsites Using Forward Modeling

Chungam¹,

Vinitnantharat²,

Wangyao³

2022

Pol. J. Environ. Stud.

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“…The measurements of the electrical resistivity could in turn be used to determine the true resistivity of the subsurface. The DC resistivity techniques have been used over the years in groundwater exploration (Gautam and Biswas 2016;Oyeyemi et al 2018a, b), engineering investigations (Oladunjoye et al 2017;Oyeyemi et al 2017Oyeyemi et al , 2020, mineral exploration (Zhang et al 2015;Sanuade et al 2018), and environmental studies (Rosales et al 2012;Akinola et al 2018;Olaojo et al 2018;Olaseeni et al 2018). However, to obtain the electrical resistivity image that would be a representation of the subsurface, the electric potential data that are measured on the field must be inverted, and forward modeling is an important step for any inversion algorithms to be used (Gao et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Direct current electrical resistivity forward modeling using comsol multiphysics

Sanuade

Amosun

Fagbemigun

et al. 2020

Model. Earth Syst. Environ.

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Forward modeling of direct current (DC) resistivity is very important for the inversion of the resistivity data to obtain the true resistivity of the subsurface. In this study, we demonstrated finite-element forward modeling of DC resistivity method with point electric source using COMSOL Multiphysics. We employed the AC/DC module in COMSOL which often provides comparatively easy implementation of models and permits exterior boundaries to be placed at infinity, a boundary condition often experienced in most geophysical problems. The validity and effectiveness of the results of numerical simulation using COMSOL Multiphysics were evaluated by comparing the output of the numerical simulations with the calculated analytic solutions. The result reveals that the numerical simulation is in agreement with the analytic solution. This study shows that COMSOL Multiphysics can be used to simulate the distribution of electrical potentials of point source in 3D space in real life and the information from this study can be used for further studies, such as DC resistivity inversions. Keywords Forward modeling • COMSOL • resistivity • Simulation List of symbols ρ a Apparent resistivity ∆V Difference in electrical potential σ Electrical conductivity n Normal to the surface σ 2 Anomaly conductivity V Electrical potential E Error analysis G Geometrical factor I Current injected I o Current intensity σ 1 Electric background conductivity V ana Analytical potential r Radius x, y and z Points

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“…The direct current resistivity (DCR) method is one of the classical geophysical techniques, which is nowadays widely used in the mineral exploration (Oldenburg et al 1997;Schoor 2005;Zhang et al 2015), groundwater (Andrade 2011;Thompson et al 2012), engineering (Chambers et al 2014;Lysdahl et al 2017), and environmental problems (LaBrecque et al 1996;Rosales et al 2012). The method is often used both for ground measurements and in the boreholes (Loke et al 2013).…”

Section: Introductionmentioning

confidence: 99%

3-D DC Resistivity Forward Modeling Using the Multi-resolution Grid

Gao

Smirnov

Smirnova

et al. 2019

Pure Appl. Geophys.

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We implemented a novel multi-resolution grid approach to direct current resistivity (DCR) modeling in 3-D. The multi-resolution grid was initially developed to solve the electromagnetic forward problem and helped to improve the modeling efficiency. In the DCR forward problem, the distribution of the electric potentials in the subsurface is estimated. We consider finite-difference staggered grid discretization, which requires fine grid resolution to accurately model electric potentials around the current electrodes and complex model geometries near the surface. Since the potential variations attenuate with depth, the grid resolution can be decreased correspondingly. The conventional staggered grid fixes the horizontal grid resolution that extends to all layers. This leads to over-discretization and therefore unnecessary high computational costs (time and memory). The non-conformal multi-resolution grid allows the refinement or roughening for the grid's horizontal resolution with depth, resulting in a substantial reduction of the degrees of freedom, and subsequently, computational requirements. In our implementation, the coefficient matrix maintains its symmetry, which is beneficial for using the iterative solvers and solving the adjoint problem in inversion. Through comparison with the staggered grid, we have found that the multiresolution grid can significantly improve the modeling efficiency without compromising the accuracy. Therefore, the multi-resolution grid allows modeling with finer horizontal resolutions at lower computational costs, which is essential for accurate representation of the complex structures. Consequently, the inversion based on our modeling approach will be more efficient and accurate.

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Research on Inversion Resolution for ERT Data and Applications for Mineral Exploration

Cited by 8 publications

References 35 publications

Evaluation of the Proper Electrode Spacing for ERI Surveys in Open Dumpsites Using Forward Modeling

Evaluation of the Proper Electrode Spacing for ERI Surveys in Open Dumpsites Using Forward Modeling

Direct current electrical resistivity forward modeling using comsol multiphysics

3-D DC Resistivity Forward Modeling Using the Multi-resolution Grid

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