Dipole-dipole resistivity imaging of the Ahuachapán-Clpilapa Geothermal field, El Salvador

Flores, Marco A. Pérez; Treviño, Enrique

doi:10.1016/s0375-6505(97)00015-1

Cited by 18 publications

(5 citation statements)

References 9 publications

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“…In the following numerical example a single‐step inversion algorithm is presented that uses the homogeneous background as a starting model m est 0 and calculates only one correction. Single‐step algorithms solving only the linearized problem around a homogeneous starting model have been widely used (Isaacson et al 1992; Lehmann 1995; Loke & Barker 1995; Perez‐Flores & Gomez‐Treviño 1997) and have proven to yield reasonable inversion results for low‐contrast models.…”

Section: Methodsmentioning

confidence: 99%

Resolution, stability and efficiency of resistivity tomography estimated from a generalized inverse approach

Friedel

2003

Geophysical Journal International

164

117

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SUMMARY Inconsistencies between an object and its image delivered by tomographical methods are inevitable. Loss of information occurs during the survey through incomplete and inaccurate data sampling and may also be introduced during the inverse procedure by smoothness constraints inadequate to the resolving power of the experimental setup. A quantitative appraisal of image quality (spatial resolution and image noise) is therefore not only required for successful interpretation of images but can be used together with measures of efficiency of the experimental design to optimize survey and inverse procedures. This paper introduces a low‐contrast inversion scheme for electrical resistivity tomography that supports the reconstructed image with estimates of model resolution, model covariance and data importance. The algorithm uses a truncated pseudo‐inverse and a line search approach to determine the maximum number of degrees of freedom necessary to fit the data to a prescribed target misfit. Though computationally expensive, the virtue of the method is that it reduces subjectivity by avoiding any empirically motivated model smoothness constraints. The method can be incorporated into a full non‐linear inversion scheme for which a posteriori quality estimates can be calculated. In a numerical 2‐D example the algorithm yielded reasonable agreement between object and image even for moderate resistivity contrasts of 10:100:1000. On the other hand, the resolving power of an exemplary four‐electrode data set containing classical dipole–dipole and non‐conventional configurations was shown to be severely affected by data inaccuracy. Insight into the resolving power as a function of space and data accuracy can be used as a guideline to designing optimized data sets, smoothness constraints and model parametrization.

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Section: Methodsmentioning

confidence: 99%

Resolution, stability and efficiency of resistivity tomography estimated from a generalized inverse approach

Friedel

2003

Geophysical Journal International

164

117

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“…8). The application of fast imaging techniques developed by Pérez-Flores and Gomez-Treviño (1997) to dipole-dipole resistivity data in the Ahuachapan-Chipilapa area resulted in resistivity images that correlate with surface hydrothermal manifestations, information derived from drilled wells, and the results of MT surveys. Árnason et al (2000), Flóvenz and Karlsdottir (2000) and Demissie (2005) have reported on TEM soundings in Iceland.…”

Section: Other Methodsmentioning

confidence: 99%

Electromagnetic sounding of geothermal zones

Spichak

Manzella

2009

Journal of Applied Geophysics

139

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“…In those situations, ERT can detect the reservoir itself, map preferential flow paths, and be useful to characterize rock properties [97][98][99][100]. Recently, several studies were carried out to image volcano hydrothermal systems with very long resistivity cables, showing that ERT is a reliable tool to detect hydrothermal features [101,102].…”

Section: Using Ert To Monitor Temperature Changesmentioning

confidence: 99%

Geophysical Methods for Monitoring Temperature Changes in Shallow Low Enthalpy Geothermal Systems

Hermans

Nguyen

Robert³

et al. 2014

Energies

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Low enthalpy geothermal systems exploited with ground source heat pumps or groundwater heat pumps present many advantages within the context of sustainable energy use. Designing, monitoring and controlling such systems requires the measurement of spatially distributed temperature fields and the knowledge of the parameters governing groundwater flow (permeability and specific storage) and heat transport (thermal conductivity and volumetric thermal capacity). Such data are often scarce or not available. In recent years, the ability of electrical resistivity tomography (ERT), self-potential method (SP) and distributed temperature sensing (DTS) to monitor spatially and temporally temperature changes in the subsurface has been investigated. We review the recent advances in using these three methods for this type of shallow applications. A special focus is made regarding the petrophysical relationships and on underlying assumptions generally needed for a quantitative interpretation of these geophysical data. We show that those geophysical methods are mature to be used within the context of temperature monitoring and that a combination of them may be the best choice regarding control and validation issues. OPEN ACCESSEnergies 2014, 7 5084

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Dipole-dipole resistivity imaging of the Ahuachapán-Clpilapa Geothermal field, El Salvador

Cited by 18 publications

References 9 publications

Resolution, stability and efficiency of resistivity tomography estimated from a generalized inverse approach

Resolution, stability and efficiency of resistivity tomography estimated from a generalized inverse approach

Electromagnetic sounding of geothermal zones

Geophysical Methods for Monitoring Temperature Changes in Shallow Low Enthalpy Geothermal Systems

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