Magnetotelluric monitoring of geodynamic processes

Svetov, B. S.; Karinskij, S. D.; Kuksa, Yu.I.; Odintsov, V. I.

doi:10.4401/ag-3920

Cited by 5 publications

(2 citation statements)

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“…Understanding the structural and textural reorganization of rocks and changes in their physicoelectric properties during the development of geological media is an important research objective because it leads to variations in measured electromagnetic parameters (apparent resistivity). Active electromagnetic monitoring of modern geodynamic processes is a valuable tool for investigating these phenomena [17,19,42]. This section explains how the reorganization of rocks and changes could be reflected in geophysical fields in situ and the possible transition to EMA through description by effective electromagnetic parameters.…”

Section: Methodsmentioning

confidence: 99%

“…These factors include lunar-solar tides, fluid dynamics, tectonic processes, and anthropogenic impacts on the lithosphere, leading to changes in the stress-strain state of the geological media [18]. Observation systems with controlled sources of electromagnetic fields are employed, including methods of magnetotelluric sounding of the Earth [19][20][21], which provides information on the physicoelectric (electromagnetic, magnetochemical, physicochemical, etc.) parameters of the lithosphere.…”

Section: Introductionmentioning

confidence: 99%

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Electromagnetic Monitoring of Modern Geodynamic Processes: An Approach for Micro-Inhomogeneous Rock through Effective Parameters

2023

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This study focuses on microscale anisotropy in rock structure and texture, exploring its influence on the macro anisotropic electromagnetic parameters of the geological media, specifically electric conductivity (σ), relative permittivity (ε), and magnetic permeability (μ). The novelty of this research lies in the advancement of geophysical monitoring methods for calculating cross properties through the estimation of effective parameters—a kind of integral macroscopic characteristic of media mostly used for composite materials with inclusions. To achieve this, we approximate real geological media with layered bianisotropic media, employing the effective media approximation (EMA) averaging technique to simplify the retrieval of the effective electromagnetic parameters (e.g., apparent resistivity–inversely proportional to electrical conductivity). Additionally, we investigate the correlation between effective electromagnetic parameters and geodynamic processes, which is supported by the experimental data obtained during monitoring studies in the Tien Shan region. The observed decrease and increase in apparent electrical resistivity values of ρk over time in orthogonal azimuths leads to further ρk deviations of up to 80%. We demonstrate that transitioning to another coordinate system is equivalent to considering gradient anisotropic media. Building upon the developed method, we derive the effective electric conductivity tensor for gradient anisotropic media by modeling the process of fracturing in a rock mass. Research findings validate the concept that continuous electromagnetic monitoring can aid in identifying natural geodynamic disasters based on variations in integral macroscopic parameters such as electrical conductivity. The geodynamic processes are closely related to seismicity and stress regimes with provided constraints. Therefore, disasters such as earthquakes are damaging and seismically hazardous.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electromagnetic Monitoring of Modern Geodynamic Processes: An Approach for Micro-Inhomogeneous Rock through Effective Parameters

2023

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Continuous and time-lapse magnetotelluric monitoring of low volume injection at Rittershoffen geothermal project, northern Alsace – France

et al. 2018

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A layer stripping approach for monitoring resistivity variations using surface magnetotelluric responses

Ogaya

Ledo

Queralt

et al. 2016

Journal of Applied Geophysics

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The resolution of surface-acquired magnetotelluric data is typically not sufficiently high enough in monitoring surveys to detect and quantify small resistivity variations produced within an anomalous structure at a given depth within the subsurface. To address this deficiency we present an approach, called "layer stripping", based on the analytical solution of the one-dimensional magnetotelluric problem to enhance the sensitivity of surface magnetotelluric responses to such subtle subsurface temporal variations in resistivity within e.g. reservoirs. Given a well-known geoelectrical baseline model of a reservoir site, the layer stripping approach aims to remove the effect of the upper, unchanging structures in order to simulate the time-varying magnetotelluric responses at depth. This methodology is suggested for monitoring all kinds of reservoirs, e.g. hydrocarbons, gas, geothermal, compress air storage, etc., but here we focus on CO2 geological storage. We study one-dimensional and three-dimensional resistivity variations in the reservoir layer and the feasibility of the method is appraised by evaluating the error of the approach and defining different detectability parameters. The geoelectrical baseline model of the Hontomín site (Spain) for CO2 geological storage in a deep saline aquifer is taken as our exemplar for studying the validity of the 1D assumption in a real scenario. We conclude that layer stripping could help detect resistivity variations and locate them in the space, showing potential to also sense unforeseen resistivity variations at all depths. The proposed approach constitutes an innovative contribution to take greater advantage of surface magnetotelluric data and to use the method as a cost-effective permanent monitoring technique in suitable geoelectrical scenarios.

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Magnetotelluric monitoring of geodynamic processes

Cited by 5 publications

References 0 publications

Electromagnetic Monitoring of Modern Geodynamic Processes: An Approach for Micro-Inhomogeneous Rock through Effective Parameters

Electromagnetic Monitoring of Modern Geodynamic Processes: An Approach for Micro-Inhomogeneous Rock through Effective Parameters

Continuous and time-lapse magnetotelluric monitoring of low volume injection at Rittershoffen geothermal project, northern Alsace – France

A layer stripping approach for monitoring resistivity variations using surface magnetotelluric responses

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