Accounting for spatially variable resolution in electrical resistivity tomography through field-scale rock-physics relations

Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. A25-A28 ◽  
Author(s):  
Kamini Singha ◽  
Stephen Moysey
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
A Priori ◽  
Rock Physics ◽  
Solute Concentration ◽  
Field Scale ◽  
Measurement Sensitivity ◽  
Resistivity Tomography ◽  
Variable Resolution ◽  
And Inversion

A number of issues impact electrical resistivity tomography (ERT) inversions: how ERT measurements sample the subsurface, the nature of subsurface heterogeneity, the geometry selected for data collection, the choice of data-misfit criteria, and regularization of the inverse problem. Lab-scale rock-physics models, typically used to estimate solute concentration from ERT, do not accommodate or account for these issues and therefore produce inaccurate geophysical estimates of solute concentrations. In contrast, the influence of measurement sensitivity and inversion artifacts can be captured by pixel-based rock-physics relationships, determined using numerical analogs that recreate the field-scale ERT experiment based on flow and transport modeling and a priori data. In the 2D synthetic example presented here, where ERT is used to monitor the transport of a saline tracer through the subsurface, improved estimates of concentration are obtained when field-scale rock-physics relationships based on numerical analogs are used.

scholarly journals A review of open software resources in python for electrical resistivity modelling

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Yonatan Garkebo Doyoro ◽  
Ping-Yu Chang ◽  
Jordi Mahardika Puntu ◽  
Ding-Jiun Lin ◽  
Tran Van Huu ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Geophysical Research ◽  
Resistivity Tomography ◽  
Subsurface Structures ◽  
Data Inversion ◽  
Scripting Language ◽  
And Inversion ◽  
Geoelectric Data ◽  
Insight Into

AbstractGeophysical modelling performs to obtain subsurface structures in agreement with measured data. Freeware algorithms for geoelectrical data inversion have not been widely used in geophysical communities; however, different open-source modelling/inversion algorithms were developed in recent years. In this study, we review the structures and applications of openly Python-based inversion packages, such as pyGIMLi (Python Library for Inversion and Modelling in Geophysics), BERT (Boundless Electrical Resistivity Tomography), ResIPy (Resistivity and Induced Polarization with Python), pyres (Python wrapper for electrical resistivity modelling), and SimPEG (Simulation and Parameter Estimation in Geophysics). In addition, we examine the recovering ability of pyGIMLi, BERT, ResIPy, and SimPEG freeware through inversion of the same synthetic model forward responses. A versatile pyGIMLi freeware is highly suitable for various geophysical data inversion. The SimPEG framework is developed to allow the user to explore, experiment with, and iterate over multiple approaches to the inverse problem. In contrast, BERT, pyres, and ResIPy are exclusively designed for geoelectric data inversion. BERT and pyGIMLi codes can be easily modified for the intended applications. Both pyres and ResIPy use the same mesh designs and inversion algorithms, but pyres uses scripting language, while ResIPy uses a graphical user interface (GUI) that removes the need for text inputs. Our numerical modelling shows that all the tested inversion freeware could be effective for relatively larger targets. pyGIMLi and BERT could also obtain reasonable model resolutions and anomaly accuracies for small-sized subsurface structures. Based on the heterogeneous layered model and experimental target scenario results, the geoelectrical data inversion could be more effective in pyGIMLi, BERT, and SimPEG freeware packages. Moreover, this study can provide insight into implementing suitable inversion freeware for reproducible geophysical research, mainly for geoelectrical modelling.

Measurement and inversion schemes for single borehole-to-surface electrical resistivity tomography surveys

2011 ◽  
Vol 8 (4) ◽  
pp. 487-497 ◽  
Author(s):  
Panagiotis Tsourlos ◽  
Richard Ogilvy ◽  
Constantinos Papazachos ◽  
Philip Meldrum
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Resistivity Tomography ◽  
And Inversion

scholarly journals Archaeological investigations in the shallow seawater environment with electrical resistivity tomography

2021 ◽  
Author(s):  
Kleanthis Simyrdanis ◽  
Nikos Papadopoulos ◽  
Jung-Ho Kim ◽  
Panagiotis Tsourlos ◽  
Ian Moffat
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
A Priori ◽  
Simulation Models ◽  
Burial Depth ◽  
Electrode Arrays ◽  
Resistivity Tomography ◽  
Priori Information ◽  
Target Characteristics ◽  
Special Environment

This work explores the applicability and effectiveness of electrical resistivity tomography in mapping archaeological relics in the shallow marine environment. The approach consists of a methodology based on numerical simulation models validated with comparison to field data. Numerical modelling includes the testing of different electrode arrays suitable for multi-channel resistivity instruments (dipole–dipole, pole–dipole, and gradient). The electrodes are placed at fixed positions either floating on the sea surface or submerged at the bottom of the sea. Additional tests are made concerning the resolving capabilities of electrical resistivity tomography with various seawater depths and target characteristics (dimensions and burial depth of the targets). Although valid a priori information, in terms of water resistivity and thickness, can be useful for constraining the inversion, it should be used judiciously to prevent erroneous information leading to misleading results. Finally, an application of the method at a field site is presented not only for verifying the theoretical results but also at the same time for proposing techniques to overcome problems that can occur due to the special environment. Numerical and field electrical resistivity tomography results indicated the utility of the method in reconstructing off-shore cultural features, demonstrating at the same time its applicability to be integrated in wider archaeological projects.

Effects of spatially variable resolution on field-scale estimates of tracer concentration from electrical inversions using Archie’s law

Geophysics ◽  
2006 ◽  
Vol 71 (3) ◽  
pp. G83-G91 ◽  
Author(s):  
Kamini Singha ◽  
Steven M. Gorelick
Keyword(s):  
Electrical Resistivity ◽  
Synthetic Data ◽  
Field Scale ◽  
Physical Processes ◽  
Formation Factor ◽  
Resistivity Tomography ◽  
Variable Resolution ◽  
Archie’S Law ◽  
Space And Time ◽  
Inverse Models

Two important mechanisms affect our ability to estimate solute concentrations quantitatively from the inversion of field-scale electrical resistivity tomography (ERT) data: (1) the spatially variable physical processes that govern the flow of current as well as the variation of physical properties in space and (2) the overparameterization of inverse models, which requires the imposition of a smoothing constraint (regularization) to facilitate convergence of the inverse solution. Based on analyses of field and synthetic data, we find that the ability of ERT to recover the 3D shape and magnitudes of a migrating conductive target is spatially variable. Additionally, the application of Archie’s law to tomograms from field ERT data produced solute concentrations that are consistently less than 10% of point measurements collected in the field and estimated from transport modeling. Estimates of concentration from ERT using Archie’s law only fit measured solute concentrations if the apparent formation factor is varied with space and time and allowed to take on unreasonably high values. Our analysis suggests that the inability to find a single petrophysical relation in space and time between concentration and electrical resistivity is largely an effect of two properties of ERT surveys: (1) decreased sensitivity of ERT to detect the target plume with increasing distance from the electrodes and (2) the smoothing imprint of regularization used in inversion.

A new coupled model for simulating the mapping of dense nonaqueous phase liquids using electrical resistivity tomography

Geophysics ◽  
2013 ◽  
Vol 78 (4) ◽  
pp. EN1-EN15 ◽  
Author(s):  
Christopher Power ◽  
Jason I. Gerhard ◽  
Panagiotis Tsourlos ◽  
Antonios Giannopoulos
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Coupled Model ◽  
Nonaqueous Phase Liquids ◽  
Hydraulic Permeability ◽  
Mass Reduction ◽  
Field Scale ◽  
Dense Nonaqueous Phase Liquids ◽  
Resistivity Tomography ◽  
Wide Range

Electrical resistivity tomography (ERT) has, for a considerable length of time, been considered promising for subsurface characterization activities at sites contaminated with dense, nonaqueous phase liquids (DNAPLs). The relatively few field studies available exhibit mixed results, and the technique has not yet become a common tool for mapping such contaminants or tracking mass reduction during their remediation. To help address this, a novel, coupled DNAPL-ERT numerical model was developed that can provide a platform for the systematic evaluation of ERT under a wide range of realistic, field-scale subsurface environments. The coupled model integrated a 3D multiphase flow model, which generates realistic DNAPL scenarios, with a 3D ERT forward model to calculate the corresponding resistivity response. Central to the coupling, and a key contribution, was a new linkage between the main hydrogeologic parameters (including hydraulic permeability, porosity, clay content, groundwater salinity and temperature, and air, water, and DNAPL contents evolving with time) and the resulting bulk electrical resistivity by integration of a variety of published relationships. Sensitivity studies conducted for a single node compared well to published correlations and for a field-scale domain demonstrated that the model is robust and sensitive to heterogeneity in DNAPL distribution and soil structure. A field-scale simulation of a DNAPL release and its subsequent remediation, monitored by ERT surface surveys, demonstrated that ERT is promising for mapping DNAPL mass reduction. The developed model provides a cost-effective avenue to test optimum ERT data acquisition, inversion, and interpretative tools, which should assist in deploying ERT strategically at contaminated sites.

scholarly journals Case study of electrical resistivity tomography measurements used in landslides investigation, Southern Poland

2018 ◽  
Vol 7 (1) ◽  
pp. 110-126 ◽  
Author(s):  
Magdalena Mita ◽  
Michał Glazer ◽  
Radosław Kaczmarzyk ◽  
Michał Dąbrowski ◽  
Karolina Mita
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
A Priori ◽  
Slope Instability ◽  
Mass Movements ◽  
Structural Differentiation ◽  
Data Set ◽  
Resistivity Tomography ◽  
Wide Range

AbstractMass movements are an ever present threat to building construction, water management, vegetation formation and biodiversity. This paper presents an approach to landslides research based on non-invasive geoelectrical method - Electrical Resistivity Tomography (ERT). Mapping and displacement monitoring of unstable slopes is crucial for the hazards prevention and assessment. The ERT technique is an effective tool to obtain structural differentiation of geological medium through interpretation of 2D electrical resistivity models. The main advantage of the method is a wide range of applicability what makes its useful during field works on a landslide. It is commonly used for measurements of slope instability, determination of shear surface, landslide susceptibility, depth of bedrock, slip plane geometry. The aim of the work is to identify the geological structures underneath three selected landslides in south Poland: in Racibórz, Milówka and Porąbka. Attempts have been focused on determination of the usefulness of the proposed ERT methodology for evaluation of possible further development of mass movements. On two investigation sites two different arrays have been used: Wenner-Schlumberger and dipole-dipole which allowed to prepare combined data set and resistivity models based on them. Forward modelling of synthetic models based on a priori information allowed to understand anomalies present on resistivity models. Applied approach ensured quality increase of final interpretation of resistivity models.

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