Induced Polarization Parameters Research Articles

Electrical resistivity tomography and induced polarization method applied for tubewell development in Alluvial deposit: A case study in MARDI Seberang Perai

Geophysical data through electrical resistivity tomography (ERT) and induced polarization (IP) can be assisted to understanding hydrogeological characteristic of groundwater aquifer. By knowing the difference in electrical resistivity and induced polarization values in alluvium deposition will facilitate to identify any groundwater occurrence. In agriculture sector, shallow tube well will be option to farmers due to more economic. The resistivity measurements proved to be a good tool for mapping the subsurface in the Alluvium, especially when used in combination with Induced Polarization parameters. Alluvial deposits or fluvial deposits are composed of particles of gravel, sand, silt or clay size that are not bound or hardened by permeable mineral, by pressure, or thermal alteration of the grains. Consideration of gravelly deposition is the higher hydraulic conductivity. Furthermore, coarse to fine sand are the second higher followed by silt and clay are the lowest values. From the case study, the electrical resistivity tomography of these deposits ranged from 40 to 1000 Ωm, while the values of chargeability were 0 to 20 mS/m. The bottom of the aquifer consisted of a layer with gravelly sandy silt, and the resistivity was 260 Ωm, while the chargeability was 6.5 mS/m. The shallow tube well in quaternary aquifer was constructed at 51 m depth with thickness of aquifer was 24 m to 51 m depth into the ground will consider for groundwater resources. The groundwater discharge from tubewell is 6.53 m3/hr in mixed gravel, sandy and silt.

Bacterial Stern layer diffusion: experimental determination with spectral induced polarization and sensitivity to nitrite toxicity

ABSTRACTSpectral induced polarization signatures have been used as proxies for microbial abundance in subsurface environments, by taking advantage of the charged properties of microbial cell membranes. The method's applicability, however, remains qualitative, and signal interpretation ambiguous. The adoption of spectral induced polarization as a robust geo‐microbiological tool for monitoring microbial dynamics in porous media requires the development of quantitative relationships between biogeochemical targets and spectral induced polarization parameters, such as biomass density and imaginary conductivity (σ″). Furthermore, deriving cell density information from electrical signals in porous media necessitates a detailed understanding of the nature of the cell membrane surface charge dynamics. We present results from a fully saturated sand‐filled column reactor experiment where Shewanella oneidensis growth during nitrate reduction to ammonium was monitored using spectral induced polarization. While our results further confirm the direct dependence of σ″ on changing cell density, Cole–Cole derived relaxation times also record the changing surface charging properties of the cells, ascribed to toxic stress due to nitrite accumulation. Concurrent estimates of cell size yield the first measurement‐derived estimation of the apparent surface ion diffusion coefficient for cells (Ds = 5.4 ±1.3 µm2 s−1), strengthening the link between spectral induced polarization and electrochemical cell polarization. Our analysis provides a theoretical framework on which to build σ″–cell density relations using bench‐scale experiments, leading to eventual robust non‐destructive monitoring of in situ microbial growth dynamics.

A discussion of 2D induced polarization effects in airborne electromagnetic and inversion with a robust 1D laterally constrained inversion scheme

Recently, the interest in the induced polarization (IP) phenomenon in airborne time-domain electromagnetic (ATEM) data has increased considerably. IP may affect the ATEM data significantly and mask underlying geologic structures. To simulate 2D airborne IP data, a 2D finite-element forward-modeling algorithm has been developed with the dispersive conductivity described by the well-known Cole-Cole model. We verify our algorithm by comparison with the 1D solution of the AarhusInv code. Two-dimensional forward responses on six synthetic models, mimicking archetypal 2D conductive and chargeable anomalies, have been generated, and the results indicate that 2D IP affects the data significantly. Differences between the 2D IP responses and the 1D IP responses are evident above the 2D anomalies and at their edges. These differences are similar to what is found when comparing 2D and 1D forward responses over conductive 2D anomalies without considering IP. We evaluate an effective robust inversion scheme to recover the 2D IP parameters using the 1D laterally constrained inversion (LCI) scheme. The inversion of the synthetic data using the robust scheme indicates that not only can the IP parameters be recovered, but also the IP inversions can provide more accurate resistivity sections than a resistivity-only inversion, in terms of resistivity values and anomaly thickness/depth. The field example from Hope Bay area in Canada is even more valuable, considering that part of the profile consists of only negative data, which cannot be inverted with a resistivity-only scheme. Furthermore, the edge effects at the anomaly boundaries are less pronounced in the IP parameters than in the resistivity parameter on the synthetic models with more conductive backgrounds.

Induced polarization in a 2.5D marine controlled-source electromagnetic field based on the adaptive finite-element method

The induced polarization (IP) in rocks and minerals is of significance to the marine controlled-source electromagnetic (CSEM) field. We propose an adaptive finite-element algorithm for the 2.5D frequency-domain forward modeling of marine CSEM that considers the induced polarization. The geoelectrical model is discretized using an unstructured triangular elemental grid that accommodates the complex topography and geoelectrical structures. We use the Cole–Cole model to describe the IP and develop a complex resistivity forward modeling algorithm. We compare the simulation results with published 1D model results and subsequently calculate the electromagnetic field for variable azimuth sources, IP parameters, and topography. Finally, we analyze the IP effect on the marine CSEM field and show that IP of oil reservoirs and topography affects the marine CSEM electromagnetic field.

A two-stage CO-PSO minimum structure inversion using CUDA for extracting IP information from MT data

The study of induced polarization (IP) information extraction from magnetotelluric (MT) sounding data is of great and practical significance to the exploitation of deep mineral, oil and gas resources. The linear inversion method, which has been given priority in previous research on the IP information extraction method, has three main problems as follows: 1) dependency on the initial model, 2) easily falling into the local minimum, and 3) serious non-uniqueness of solutions. Taking the nonlinearity and nonconvexity of IP information extraction into consideration, a two-stage CO-PSO minimum structure inversion method using compute unified distributed architecture (CUDA) is proposed. On one hand, a novel Cauchy oscillation particle swarm optimization (CO-PSO) algorithm is applied to extract nonlinear IP information from MT sounding data, which is implemented as a parallel algorithm within CUDA computing architecture; on the other hand, the impact of the polarizability on the observation data is strengthened by introducing a second stage inversion process, and the regularization parameter is applied in the fitness function of PSO algorithm to solve the problem of multi-solution in inversion. The inversion simulation results of polarization layers in different strata of various geoelectric models show that the smooth models of resistivity and IP parameters can be obtained by the proposed algorithm, the results of which are relatively stable and accurate. The experiment results added with noise indicate that this method is robust to Gaussian white noise. Compared with the traditional PSO and GA algorithm, the proposed algorithm has more efficiency and better inversion results.

Resolution of well-known resistivity equivalences by inclusion of time-domain induced polarization data

The principle of equivalence is known to cause nonuniqueness in interpretations of direct current (DC) resistivity data. Low- or high-resistivity equivalences arise when a thin geologic layer with a low/high resistivity is embedded in a relative high-/low-resistivity background formation causing strong resistivity-thickness correlations. The equivalences often make it impossible to resolve embedded layers. We found that the equivalence problem could be significantly reduced by combining the DC data with full-decay time-domain induced polarization (IP) measurements. We applied a 1D Markov chain Monte Carlo algorithm to invert synthetic DC data of models with low- and high-resistivity equivalences. By applying this inversion method, it is possible to study the space of equivalent models that have an acceptable fit to the observed data, and to make a full sensitivity analysis of the model parameters. Then, we include a contrast in chargeability into the model, modeled in terms of spectral Cole-Cole IP parameters, and invert the DC and IP data in combination. The results show that the addition of IP data largely resolves the DC equivalences. Furthermore, we present a field example in which DC and IP data were measured on a sand formation with an embedded clay layer known from a borehole drilling. Inversion results show that the DC data alone do not resolve the clay layer due to equivalence problems, but by adding the IP data to the inversion, the layer is resolved.

Simulation of membrane polarization of porous media with impedance networks

ABSTRACTThe spectral induced polarization method is supposed to have some potential to provide useful information on hydraulic properties of the subsurface. One difficulty for the practical implementation is the simulation of underlying physical processes at the pore scale and their upscaling to hydraulically relevant scales. We extend an existing semi‐analytical membrane polarization model to two‐ and three‐dimensional impedance networks, which are numerically solved to obtain a spectral induced polarization response that can be compared to measured data.The original model consists of two cylinders with different sizes. The model has been shown to be able to reproduce some basic features of spectral induced polarization spectra measured in the laboratory, but it is unable to meet the complexity of macroscopic porous media structures, which can be found within unconsolidated sediments or rocks. To approach realistic pore space geometry, we connect different combinations of cylinders to networks. We treat the smaller of the two cylinders as a pore throat. The pore throat distribution in the network is chosen by matching measured pore throat radii distributions obtained from the mercury injection method. The large cylinder is treated as the (large) pore body, and its radii are associated to the pore throats using existing relationships.We compare the behaviour of the networks with real porous media by using sandstone samples for which both the electrical and petrophysical properties have been measured. We adjust the geometrical parameters of the network, i.e., pore lengths, pore radii, and their relative occurrences, such that they match the measured parameters (specific internal surface area, pore throat distribution, and porosity) of the sandstone samples. The measured spectral induced polarization parameters, like the maximum phase shift and the characteristic relaxation time, are qualitatively consistent with our simulation results.

Bayesian inference of spectral induced polarization parameters for laboratory complex resistivity measurements of rocks and soils

Spectral induced polarization (SIP) measurements are now widely used to infer mineralogical or hydrogeological properties from the low-frequency electrical properties of the subsurface in both mineral exploration and environmental sciences. We present an open-source program that performs fast multi-model inversion of laboratory complex resistivity measurements using Markov-chain Monte Carlo simulation. Using this stochastic method, SIP parameters and their uncertainties may be obtained from the Cole-Cole and Dias models, or from the Debye and Warburg decomposition approaches. The program is tested on synthetic and laboratory data to show that the posterior distribution of a multiple Cole-Cole model is multimodal in particular cases. The Warburg and Debye decomposition approaches yield unique solutions in all cases. It is shown that an adaptive Metropolis algorithm performs faster and is less dependent on the initial parameter values than the Metropolis-Hastings step method when inverting SIP data through the decomposition schemes. There are no advantages in using an adaptive step method for well-defined Cole-Cole inversion. Finally, the influence of measurement noise on the recovered relaxation time distribution is explored. We provide the geophysics community with a open-source platform that can serve as a base for further developments in stochastic SIP data inversion and that may be used to perform parameter analysis with various SIP models.

Prediction of permeability of cement-admixed soft clay using resistivity and time-domain IP measurements

Permeability is one of the most important petrophysical parameters, which unfortunately is quite difficult to be tested and estimated, particularly for the fine-grained soils and mixed soils. Prediction of permeability based on geophysical measurements is currently one of the most challenging issues in petrophysics. There have been recently reported some empirical relationships between permeability, resistivity and spectral induced polarization (SIP) parameters for a porous medium. However, the disadvantage of this approach is the very scarcity of SIP data as most of practical measurements are time-domain IP. In this study, a detailed overview of permeability prediction models using resistivity and spectral IP data was made. More than that, an innovative approach using resistivity and time-domain IP measurements to predict permeability of cement-admixed Bangkok clay was proposed and successfully applied for tested samples based on measurements of resistivity and time-domain IP data. A good amount of geotechnical and geophysical tests was conducted to investigate the time-dependent development of strength, porosity, and permeability of cement-mixed Bangkok soft clay samples during a 28-day curing process. The permeability predicted by resistivity and chargeability model matched well with permeability measured by consolidation testing. In addition, a series of correlations between unconfined compressive strength, porosity and permeability as measured by geotechnical testing and resistivity and chargeability as measured by geophysical testing were found.

Electrical Resistivity Tomography and Induced Polarization for Mapping the Subsurface of Alluvial Fans: A Case Study in Punata (Bolivia)

Conceptual models of aquifer systems can be refined and complemented with geophysical data, and they can assist in understanding hydrogeological properties such as groundwater storage capacity. This research attempts to use geoelectrical methods, Electrical Resistivity Tomography and Induced Polarization parameters, for mapping the subsurface in alluvial fans and to demonstrate its applicability; the Punata alluvial fan was used as a case study. The resistivity measurements proved to be a good tool for mapping the subsurface in the fan, especially when used in combination with Induced Polarization parameters (i.e., Normalized Chargeability). The Punata alluvial fan characterization indicated that the top part of the subsurface is composed of boulders in a matrix of finer particles and that the grain size decreases with depth; the electrical resistivity of these deposits ranged from 200 to 1000 Ωm, while the values of normalized chargeability were lower than 0.05 mS/m. The bottom of the aquifer system consisted of a layer with high clay content, and the resistivity ranged from 10 to 100 Ωm, while the normalized chargeability is higher than 0.07 mS/m. With the integration of these results and lithological information, a refined conceptual model is proposed; this model gives a more detailed description of the local aquifer system. It can be concluded that geoelectrical methods are useful for mapping aquifer systems in alluvial fans.

Quantitative estimation of intrinsic induced polarization and superparamagnetic parameters from airborne electromagnetic data

The primary aim of my research is to improve the characterization of induced polarization (IP) responses in airborne electromagnetic (AEM) survey data. The principal objectives are to test alternative methodologies for quantitative modeling and inversion to extract the spatial variation of IP parameters using the inductively thin-sheet model. The methods tested first fit, by nonnegative least squares, an AEM decay to the early delay time data, using thin-sheet basis functions. This modeled AEM decay is assumed to represent the IP source. It is then convolved with a few Cole-Cole models spanning the range of parameter sensitivity to get IP basis functions appropriate for the AEM excitation. Method 1 fits a linear sum of several AEM basis functions plus one IP basis function at a time and chooses the model with least-fitting error at late delay times. Method 2 fits a linear sum of several IP and several AEM basis functions. Both methods fit IP affected airborne data well, with normalized fitting errors being reduced by a significant factor when IP affects the data and is taken into account. Using penalty weights, superparamagnetic (SPM) effects can be simultaneously estimated in the fitting process. Without such weighting, SPM and IP parameter estimations are unstable. Cole-Cole models predict that the sensitivity of inductive airborne IP collected at 25 or 30 Hz base frequency indicates little overlap with galvanic ground IP collected with a 0.125 Hz waveform. Many easy IP sulfide targets with IP physical properties determined by ground surveys are predicted not to have a detectable airborne IP response. Clays, however, are predicted to have a small detectable background response that for airborne data would not be well-fitted by a single Cole-Cole response.

Comparing induced polarization responses from airborne inductive and galvanic ground systems: Tasmania

We have first analyzed the ability of polarizable and superparamagnetic thin sheets in the near surface to fit airborne electromagnetic (AEM) data using data from western Tasmania. Then we analyzed the results of such fitting in the context of geologic mapping and available ground induced polarization (IP) data. Small to large IP effects were found to considerably improve the fit to the observed AEM data, and the overall fitted IP parameters were spatially consistent. However, the locations of anomalous IP parameters were quite distinct from anomalies in other geophysical data. The airborne chargeability highs were adjacent to or surrounded the ground chargeability highs in the five cases analyzed from Tasmanian data. Modeling using the established Cole-Cole physical property values for sulfides predicts that an inductive airborne system is insensitive to many conventional IP targets, unless the mineral grain size is substantially less than 1 mm. In the cases in which airborne IP responses were adjacent to ground IP targets, we hypothesized that the airborne IP may be finer grained minerals in an alteration halo surrounding the sulfide sources of the large ground IP anomalies. Surficial clays encountered in drillholes did not have significant ground or airborne IP responses. A companion paper comes to a similar conclusion using ground and airborne data from a copper deposit in New South Wales.

Application of the Debye decomposition approach to analysis of induced-polarization profiling data (Julietta gold-silver deposit, Magadan Region)

Time-domain induced polarization (IP) data are used for approach to ore prospecting problems on the flanks of the Julietta gold-silver deposit. IP time-domain data are analyzed on the basis of the Debye decomposition, which allows reconstruction of the relaxation time distribution. Experimental dependences of the IP parameters on the main petrophysical properties of disseminated ores were used to interpret field data. The Debye decomposition helped to identify zones of hydrothermally and metasomatically altered rocks containing finely disseminated sulfide minerals, which were missed when using the standard procedure for the analysis of IP data. The estimated content of sulfide minerals in the altered rocks agrees with geological data.

Influence of non-aqueous phase liquid configuration on induced polarization parameters: Conceptual models applied to a time-domain field case study

Resistivity and induced polarization (IP) measurements on soil contaminated with non-aqueous phase liquids (NAPLs) show a great variety in results in previous research. Several laboratory studies have suggested that the presence of NAPLs in soil samples generally decrease the magnitude of the IP-effect, while others have indicated the opposite. A number of conceptual models have been proposed suggesting that NAPLs can alter the pore space in different ways, e.g. by coating the grain surfaces and thus inhibiting grain polarization, or by changing the pore throat size and thus affecting the membrane polarization mechanism. The main aim of this paper is to review previously published conceptual models and to introduce some new concepts of possible residual NAPL configurations in the pore space. Time domain induced polarization measurements were performed at a NAPL contaminated field site, and the data were inverted using the Constant Phase Angle (CPA) model and the Cole–Cole model respectively. No significant phase anomalies were observed in the source area of the contamination when the CPA inverted profiles were compared with soil sampling results of free-phase contaminant concentrations. However, relatively strong phase and normalized phase anomalies appeared next to the source area, where residual free-phase presence could be expected according to the chemical data. We conclude that depending on the NAPL configuration, different spectral IP responses can be expected. In previous research, the NAPL configurations in different samples or field sites are often unknown, and this may to some extent explain why different results have been achieved by different authors. In our field case, we believe that the NAPL forms a more or less continuous phase in the pore space of the source zone leading to an absence of IP anomalies. The increase in phase and normalized phase angle observed next to the source zone is interpreted as a degradation zone. The ongoing biodegradation may have led to a fractionation of the continuous NAPL in the outer part of the original source zone, leading to residual presence of isolated NAPL droplets in the soil pores. With such NAPL configurations, an increased polarization can be expected according to the electrochemical- and membrane polarization mechanisms. More research is needed to confirm the effects of different NAPL configuration on spectral IP parameters.

Induced polarization effect in reservoir rocks and its modeling based on generalized effective-medium theory

One of the major tasks of the petroleum resource-efficient technologies (pREFFIT) is the development and improvement of the methods of exploration for energy resources. This review paper summarizes the results of the research on induced polarization (IP) effect in reservoir rocks conducted by the University of Utah Consortium for Electromagnetic Modeling and Inversion (CEMI) and TechnoImaging. The electrical IP effectin hydrocarbon (HC) bearing reservoir rocks having nonmetallic minerals is usually associated with membrane polarization, which is caused by a variation in the mobility of the ions throughout the rock structure. This mobility is related to the size and shape of the pores filled with electrolyte and the double electrical layers. We have studied the IP response of multiphase porous systems by conducting complex resistivity (CR) frequency-domain IP measurements for two different groups of samples: sands and sandstones containing salt water in pores and those whose unsaturated pores were filled with synthetic oil.We have also studied selected carbonate reservoir formations, typical of some major HC deposits. The generalized effective-medium theory of induced polarization (GEMTIP) was used to analyze the IP parameters of the measured responses. This paper presents a conceptual model of polarizing clusters to explain the observed IP phenomena. The results of this study show that the HC bearing sands and sandstone samples and carbonate rocks are characterized by a significant IP response. These experimental observations, compared with the theoretical modeling based on the GEMTIP approach, confirm earlier geophysical experiments with the application of the IP method for HC exploration.

Induced polarization effect in reservoir rocks and its modeling based on generalized effective-medium theory

One of the major tasks of the petroleum resource-efficient technologies (pREFFIT) is the development and improvement of the methods of exploration for energy resources. This review paper summarizes the results of the research on induced polarization (IP) effect in reservoir rocks conducted by the University of Utah Consortium for Electromagnetic Modeling and Inversion (CEMI) andTechnoImaging.The electrical IP effect in hydrocarbon (HC) bearing reservoir rocks having nonmetallic minerals is usually associated with membrane polarization, which is caused by a variation in the mobility of the ions throughout the rock structure.This mobility is related to the size and shape of the pores filled with electrolyte and the double electrical layers. We have studied the IP response of multiphase porous systems by conducting complex resistivity (CR) frequency-domain IP measurements for two different groups of samples: sands and sandstones containing salt water in pores and those whose unsaturated pores were filled with synthetic oil. We have also studied selected carbonate reservoir formations, typical of some major HC deposits. The generalized effective-medium theory of induced polarization (GEMTIP) was used to analyze the IP parameters of the measured responses. This paper presents a conceptual model of polarizing clusters to explain the observed IP phenomena. The results of this study show that the HC bearing sands and sandstone samples and carbonate rocks are characterized by a significant IP response. These experimental observations, compared with the theoretical modeling based on the GEMTIP approach, confirm earlier geophysical experiments with the application of the IP method for HC exploration. © 2015 Tomsk Polytechnic University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer review under responsibility of Tomsk Polytechnic University.

Time-Domain Spectral Induced Polarization Based on Pseudo-random Sequence

To reduce noise during electrical prospecting, we hereby propose a new method using correlation identification technology and conventional electrical exploration devices. A correlation operation can be carried out with the transmitted pseudo-random sequence and received time signal to suppress the random noise, and the time-domain impulse response and frequency response of the frequency domain of the underground media can be obtained. At the same time, using a dual Cole–Cole model to fit a complex resistivity spectrum, which is close to the frequency response, we can get a variety of induced polarization parameters and electromagnetic parameters of subsurface, which can provide more useful information for the exploration of mineral resources. This time domain prospecting method can effectively improve the efficiency of the spectral induced polarization method. In this article, we have carried out theoretical calculations and a simulation to prove the feasibility of such a method.

Induced polarization method in hydrocarbon prospecting

The paper presents the method of induced polarization (IP) and focuses on its application to direct prospecting for hydrocarbon deposits. Induced polarization parameters that are obtained from measurements in time domain and frequency domain are presented. Classification of minerals and rocks based on induced polarization parameter was analyzed. Five examples of application of induced polarization method to discovering and recognizing hydrocarbon deposits by foreign companies were given. Methodology of field works made in Carpathians and Carpathian Foredeep with the use of equatorial and dipole-dipole arrays was described. Maps of phase parameter evaluated from results of equatorial array measurements for Grabownica and Rudka deposits as well as the plot of phase parameter along profile cutting the area of Rylowa deposit were analyzed. Cross-sections of three induced polarization parameters were made and analyzed with CSAMT resistivity sections in the area of Rudka deposit.

On the estimation of specific surface per unit pore volume from induced polarization: A robust empirical relation fits multiple data sets

We analyze the relationship between induced polarization (IP) parameters and the specific surface area normalized to the pore volume [Formula: see text] for an extensive sample database. We find that a single linear imaginary conductivity-[Formula: see text] relation holds across a range of single-frequency IP data sets composed of sandstones and unconsolidated sediments that lack an appreciable metallic mineral content. We also apply a recent approach defined as Debye decomposition (DD) to determine normalized chargeability [Formula: see text], a global estimate of polarization magnitude from available spectral IP (SIP) data sets. A strong linear relationship between [Formula: see text] and [Formula: see text] is also found across multiple data sets. However, SIP model parameters determined for samples containing metallic minerals are approximately two orders of magnitude greater than for the model parameters estimated for the nonmetallic sample database. We propose a concept of “polarizability of the mineral-fluid interface per unit [Formula: see text]” to explain this difference, which is supported by the observed dependence of IP parameters on fluid conductivity between sample types. We suggest that this linear IP-[Formula: see text] relation can be considered the IP equivalent of the classical Archie empirical relation. Whereas the Archie relation describes a power-law relation between electrical conductivity due to electrolytic conduction through the available interconnected pore volume, the IP-[Formula: see text] relation is an equivalent relation between mineral-fluid interfacial polarization and available pore surface area.

Relationships between induced polarization relaxation time and hydraulic properties of sandstone

We investigated electrical and physical–chemical properties of six sandstone samples with contrasting mineralogical characteristics and with hydraulic conductivity varying in a wide range. The electrical data were obtained from time domain spectral induced polarization (IP) measurements. We inverted the IP decays to relaxation time distributions, and then compared the modal relaxation times with the dominant pore throat diameters obtained from the Mercury Injection Capillary Pressure (MICP) data. We found a positive logarithmic relationship between the relaxation time and the pore throat diameter. Also, we found the normalized chargeability (an integral IP parameter) to be positively correlated with the clay content. These two results suggest that the polarization of our sandstones is controlled by the pore throat distribution, and by the clay content. The logarithmic relationship contradicts previous theories, and is not universal. Adopting an approach of Kruschwitz and her co-workers, we calculated the effective diffusivity from IP and MICP data, and we found the effective diffusivity values ranging from 2.9 × 10−13 to 1.6 × 10−10 m2 s−1. High diffusivity values, typical of surface diffusion, were obtained for clean sandstones. Low diffusivity values were obtained for clayey sandstones, and they were one to two orders of magnitude lower than those characteristic of the surface diffusion. We proposed two mechanisms to explain the ‘slow’ diffusion: (1) the effect of surface tortuosity of pore throats filled with clay minerals and (2) the effect of pore geometry. These two effects represent an obstacle in assessing the pore throat diameter and hydraulic conductivity of sandstones with large specific surface and clay content on the basis of spectral IP measurements. However, we believe that the sandstones featuring ‘slow’ diffusion can be discriminated based on the integral polarization parameters, and that the relaxation time remains a valuable parameter for assessing hydraulic properties of clean sandstones.