We combined two completely different methods measuring the frequency-dependent electrical properties of moist porous materials in order to receive an extraordinary large frequency spectrum In the low-frequency (LF) range, complex electrical resistivity between 1 mHz and 45 kHz was measured for three different soils and sandstone, using the spectral induced polarization (SIP) method with a four electrode cell In the high-frequency (HF) radio to microwave range, complex dielectric permittivity was measured between 1MHz and 10 GHz for the same samples using dielectric spectroscopy by means of the coaxial transmission line technique The combined data sets cover 13 orders of magnitude and were transferred into their equivalent expressions: the complex effective dielectric permittivity and the complex effective electrical conductivityWe applied the Kramers-Kronig relation in order to justify the validity of the data combination A new phenomenological model that consists of both dielectric permittivity and electrical conductivity terms in a Debye- and Cole–Cole-type manner was fitted to the spectra The combined permittivity and conductivity model accounts for the most common representations of the physical quantities with respect to the individual measuring method A maximum number of four relaxation processes was identified in the analysed frequency range Among these are the free water and different interfacial relaxation processes, the Maxwell-Wagner effect, the counterion relaxation in the electrical double layer and the direct-current electrical conductivity There is evidence that free water relaxation does not affect the electrical response in the SIP range Moreover, direct current conductivity contribution (bulk and interface) dominates the losses in the HF range Interfacial relaxation processes with relaxations in the HF range are broadly distributed down to the LF range The slowest observed process in the LF range has a minor contribution to the HF response

Ultra-broad-band electrical spectroscopy of soils and sediments—a combined permittivity and conductivity model

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Modelling the spectral induced polarization response of water-saturated sands in the intermediate frequency range (102–105 Hz) using mechanistic and empirical approaches Thomas Kremer, Myriam Schmutz, Philippe Leroy, Pierre Agrinier, Alexis Maineult

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Modelling the spectral induced polarization response of water-saturated sands in the intermediate frequency range (102–105 Hz) using mechanistic and empirical approaches

ERT monitoring of gas injection into water saturated sands: Modelling and inversion of cross-hole laboratory data

Clay material characterization is of importance for many geo-engineering and environmental applications, and geo-electrical methods are often used to detect them in the subsurface. Spectral induced...

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Spectral Induced Polarization Characterization of Non-Consolidated Clays for Varying Salinities—An Experimental Study

S U M M A R Y There are growing interests in using geophysical tools to characterize the microstructure of geomaterials because of the non-invasive nature and the applicability in field. In these applications, multiple types of geophysical data sets are usually processed separately, which may be inadequate to constrain the key feature of target variables. Therefore, simultaneous processing of multiple data sets could potentially improve the resolution. In this study, we propose a method to estimate pore size distribution by joint inversion of nuclear magnetic resonance (NMR) T2 relaxation and spectral induced polarization (SIP) spectra. The petrophysical relation between NMR T2 relaxation time and SIP relaxation time is incorporated in a nonlinear least squares problem formulation, which is solved using Gauss–Newton method. The joint inversion scheme is applied to a synthetic sample and a Berea sandstone sample. The jointly estimated pore size distributions are very close to the true model and results from other experimental method. Even when the knowledge of the petrophysical models of the sample is incomplete, the joint inversion can still capture the main features of the pore size distribution of the samples, including the general shape and relative peak positions of the distribution curves. It is also found from the numerical example that the surface relaxivity of the sample could be extracted with the joint inversion of NMR and SIP data if the diffusion coefficient of the ions in the electrical double layer is known. Comparing to individual inversions, the joint inversion could improve the resolution of the estimated pore size distribution because of the addition of extra data sets. The proposed approach might constitute a first step towards a comprehensive joint inversion that can extract the full pore geometry information of a geomaterial from NMR and SIP data.

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Joint inversion of NMR and SIP data to estimate pore size distribution of geomaterials

/pdf/laboratory-monitoring-of-co2-injection-in-saturated-silica-2hz3fbnkeh.pdf

Alexis Maineult

Papers

Modelling the spectral induced polarization response of water-saturated sands in the intermediate frequency range (102–105 Hz) using mechanistic and empirical approaches

Laboratory monitoring of CO2 injection in saturated silica and carbonate sands using spectral induced polarization

Special Issue on New trends in Induced Polarization -- Part 1