Induced polarization response of porous media with metallic particles — Part 5: Influence of the background polarization

Geophysics ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. E77-E96 ◽  
Author(s):  
André Revil ◽  
Michael F. Sleevi ◽  
Deqiang Mao
Keyword(s):  
Porous Materials ◽  
Tap Water ◽  
Current Model ◽  
Clay Content ◽  
Peak Frequency ◽  
Exchange Capacity ◽  
Induced Polarization ◽  
Data Sets ◽  
Phase Lag ◽  
Polarization Spectra

Very often, ore bodies are found in altered porous materials that are rich in clay minerals. These altered rocks are in turn characterized by a relatively high normalized chargeability (product of the chargeability by the high frequency conductivity) or electrical quadrature conductivity with respect to clay-free materials. We have performed 36 experiments in which dispersed pyrite grains were mixed with a background host material composed of some pore water (NaCl, [Formula: see text] at 25°C or tap water), Na-exchanged bentonite, and silica grains. The induced polarization spectra were obtained in the frequency range of 1 mHz to 45 kHz at room temperature ([Formula: see text]). The spectra of the background porous materials alone (i.e., without pyrite) were also measured. The normalized chargeability and the quadrature conductivity of the sand-clay mixtures are consistent with available theoretical relationships. These new data complete previous data sets showing a clear relationship among the normalized chargeability, quadrature conductivity, surface conductivity, and cation exchange capacity. Bentonite is characterized by very high quadrature and surface conductivities. The normalized chargeability and the quadrature conductivity of the sand-clay mixtures (no pyrite) increase with the clay content. In the presence of pyrite, the chargeability and the phase lag depend primarily on the volume content of pyrite in a predictable way. The Cole-Cole exponent, characterizing the particle size distribution of the pyrite grains, is independent of the clay content. Still, in the presence of pyrite, the magnitude of the phase peak and the phase peak frequency depend on the clay content in a way that is not explained by the current model. We have observed that the Cole-Cole relaxation time, in the presence of pyrite, is inversely proportional to the conductivity of the background material.

Investigating cable effects in spectral induced polarization imaging at the field scale using multicore and coaxial cables

Geophysics ◽  
2020 ◽  
pp. 1-49
Author(s):  
Adrian Flores Orozco ◽  
Lukas Aigner ◽  
Jakob Gallistl
Keyword(s):  
Signal To Noise Ratio ◽  
Electromagnetic Coupling ◽  
Induced Polarization ◽  
Coaxial Cable ◽  
Imaging Method ◽  
Data Sets ◽  
Phase Lag ◽  
Imaging Data ◽  
Measuring Device ◽  
Spectral Induced Polarization

The Spectral Induced Polarization (SIP) method has emerged as a well-suited laboratory technique to characterize hydrogeological and biogeochemical parameters in soil samples. However, field applications of the SIP imaging method are still rare, which can be attributed to the particular care required to minimize the contamination of the data by electromagnetic coupling. To date, field procedures rely on the use of two different cables separating the current and potential dipoles to improve the quality of the SIP readings, although this increases the efforts in the field and might reduce the depth of investigation or the spatial resolution of the data. To overcome these limitations, we investigate here the use of a single coaxial cable, as an alternative to improve data quality and simplify field procedures. We present a thoughtful evaluation of SIP imaging data collected with the same measuring device using a coaxial cable and a combination of multicore cables of different length and manufacturers. Data sets collected with a single coaxial cable reveal a significantly lower number of outliers and high spatial consistency between the phase-lag readings, even for measurements collected with a coaxial cable five times longer than the length of the profile. Furthermore, the data collected with coaxial cables reveal an improved quality for deeper measurements (with lower signal-to-noise ratio) in comparison to data sets collected with separated cables. Our results demonstrate that the use of coaxial cables might permit the collection of SIP readings with high quality and similar field procedures to those used in resistivity surveys.

Induced polarization response of porous media with metallic particles — Part 4: Detection of metallic and nonmetallic targets in time-domain induced polarization tomography

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. D359-D375 ◽  
Author(s):  
Deqiang Mao ◽  
André Revil ◽  
John Hinton
Keyword(s):  
Time Domain ◽  
Clay Mineralogy ◽  
Clay Content ◽  
Exchange Capacity ◽  
Induced Polarization ◽  
Polarization Tomography ◽  
Sandbox Experiments ◽  
Best Parameter ◽  
The Right ◽  
Water Saturated

Time-domain induced polarization (TDIP) is a nonintrusive imaging technique of the subsurface that can be used to localize polarizable bodies including metallic objects and clay-rich materials. We first reviewed recent advances in the interpretation of induced polarization data. Then, we performed laboratory and sandbox experiments to determine the frequency-domain and TDIP signature of (1) a metal bar in sand, (2) dispersed semiconductors (e.g., pyrite) in sand, and (3) bentonite. In the case of the sandbox experiments, the three types of bodies were localized in the center of the sandbox, which was filled with water-saturated sand. We determined that chargeability was the best parameter to characterize metallic bodies (the metallic bar and the dispersed pyrite), whereas normalized chargeability was the best parameter to characterize the cation exchange capacity and therefore the clay content of the subsurface at a given clay mineralogy. For interpretation purposes, it was therefore important to display the right parameters in TDIP depending on the type of target we wanted to image for engineering applications.

Induced polarization response of porous media with metallic particles — Part 6: The case of metals and semimetals

Geophysics ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. E97-E110 ◽  
Author(s):  
André Revil ◽  
Deqiang Mao ◽  
Zhenlu Shao ◽  
Michael F. Sleevi ◽  
Deming Wang
Keyword(s):  
Relaxation Time ◽  
Tap Water ◽  
Core Sample ◽  
Induced Polarization ◽  
Copper Plate ◽  
Secondary Source ◽  
Water Conductivity ◽  
Metallic Particles ◽  
Two Parameters ◽  
Polarization Spectra

We collected spectral induced polarization spectra with clean sand mixed with metallic particles (either silver, graphite, copper, steel, magnetite, or pyrite particles). The initial pore water conductivity was either 1500 or [Formula: see text] depending on the experiments (25°C, NaCl). For each of the 15 experiments, we used a narrow and unimodal grain size distribution for the metallic particles. The resulting polarization spectra display clear polarization peaks in the phase and can be fitted with a Cole-Cole complex conductivity model. In addition to this, the chargeability scales with the volume content of the metallic particles in a way that is consistent with the theory of disseminated metallic particles in a weakly polarizable background. Similarly, the phase scales with the content of the metallic particles in a predictable way. The Cole-Cole relaxation time shows a rough dependence with the mean particle size. The trend between these two parameters can be used to determine an apparent diffusion coefficient for the charge carriers responsible for the polarization. Finally, we conducted a laboratory sandbox experiment in which we put a copper plate in tap water-saturated sand. We use an approach based on self-potential tomography and compactness to invert the secondary source current density from the secondary voltages associated with time-domain induced polarization. With this approach, we localized the copper plate and determined a value for the relaxation time that is consistent with the laboratory core sample experiments.

Ratio of plant to soil concentrations of strontium-85 and its relation to properties of Greek soils

1991 ◽  
Vol 116 (2) ◽  
pp. 275-279 ◽  
Author(s):  
E. P. Papanicolaou ◽  
C. G. Apostolakis ◽  
V. Skarlou ◽  
C. Nobeli ◽  
P. Kritidis
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Plant Material ◽  
Clay Content ◽  
Exchange Capacity ◽  
Absolute Value ◽  
Plant Parts ◽  
Stems And Leaves ◽  
Lower Variability ◽  
Edible Parts

SUMMARYPlant:soil ratios (CRs) of 85Sr concentration were studied in wheat, lucerne, lettuce, radish, string bean (Phaseolus vulgaris), and cucumber grown in pots in eight Greek soil types in a glasshouse pot experiment in 1989.The CRs of the crops and of the plant parts studied differed according to soil type. They ranged from 0·034–1·39 for wheat grains to 7·6–36·5 for cucumber stems and leaves. The CRs of the edible parts were much lower than those of the other plant material.The correlation between CRs and clay content was negative and, in most cases, significant (P = 0·05–0·01) or highly significant (P < 0·01). The negative correlation improved (higher absolute value of r, lower variability) if clay plus silt content or cation exchange capacity was used instead of clay content.The correlation between CRs and soil properties was greatest for soil pH (r = –0·89) and decreased in the order: pH > total clay plus silt ≃ cation exchange capacity > total clay.

The Pressure Dependence of the Archie Cementation Exponent for Samples from the Ordovician Goldwyer Shale Formation in Australia

SPE Journal ◽  
2021 ◽  
pp. 1-11
Author(s):  
Zhiqi Zhong ◽  
Lionel Esteban ◽  
Reza Rezaee ◽  
Matthew Josh ◽  
Runhua Feng
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Complex Impedance ◽  
Clay Content ◽  
Exchange Capacity ◽  
Shale Formations ◽  
Fluid Saturation ◽  
Confining Pressures ◽  
Log Interpretation

Summary Applying the realistic cementation exponent (m) in Archie’s equation is critical for reliable fluid-saturation calculation from well logs in shale formations. In this study, the cementation exponent was determined under different confining pressures using a high-salinity brine to suppress the surface conductivity related to the cation-exchange capacity of clay particles. A total of five Ordovician shale samples from the Canning Basin, Australia, were used for this study. The shale samples are all illite-rich with up to 60% clay content. Resistivity and porosity measurements were performed under a series of confining pressures (from 500 to 8,500 psi). Nuclear magnetic resonance (NMR) was used to obtain porosity and pore-size distribution and to detect the presence of residual oil. The complex impedance of samples was determined at 1 kHz to verify the change in pore-size distribution using the POLARIS model (Revil and Florsch 2010). The variation of shale resistivity and the Archie exponent m at different pressures is caused by the closure of microfractures at 500 psi, the narrowing of mesopores/macropores between 500 and 3,500 psi, and the pore-throat reduction beyond 3,500 psi. This study indicates that unlike typical reservoirs, the Archie exponent m for shale is sensitive to depth of burial because of the soft nature of the shale pore system. An equation is developed to predict m under different pressures after microfracture closure. Our study provides recommended experimental procedures for the calculation of the Archie exponent m for shales, leading to improved accuracy for well-log interpretation within shale formations when using Archie-basedequations.

scholarly journals Effect of termite activity on soil under different land management strategies

2017 ◽  
Vol 38 (1) ◽  
pp. 143
Author(s):  
Liane Barreto Alves Pinheiro ◽  
Rodrigo Camara ◽  
Marcos Gervasio Pereira ◽  
Eduardo Lima ◽  
Maria Elizabeth Fernandes Correia ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Management Strategies ◽  
Chemical Properties ◽  
Clay Content ◽  
Exchange Capacity ◽  
Termite Mounds ◽  
Eucalyptus Plantation ◽  
Exchangeable Acidity ◽  
Calcium And Magnesium ◽  
Surrounding Soil

Mound-building termites are important agents of soil bioperturbation, but these species have not been extensively studied thus far. The present study aimed to evaluate the soil particle-size and the chemical attributes of termite mounds and the surrounding soil under different land use strategies. A one-hectare plot was defined for an unmanaged degraded pasture, planted pasture, and for a eucalyptus Corymbia citriodora plantation. In each plot, the top, center, and base sections of five Cornitermes cumulans mounds, and the surrounding soil at the depths of 0-5; 5-10; 10-20 cm, were sampled in the Pinheiral, Rio de Janeiro state. In the three areas, the center of the mounds contained higher clay content, organic carbon, phosphorous, calcium and magnesium, total bases, and cation exchangeable capacity, when compared to the top, base, and the surrounding soils. However, the center had lower values of exchangeable acidity and potassium, of the three areas. In the eucalyptus plantation, the values of pH, total bases, calcium, and magnesium were lower, whereas aluminum, exchangeable acidity, sodium, and cation exchange capacity were higher both in the mounds and in the surrounding soil, in relation to the pastures. There were no differences among the three areas in terms of organic carbon, potassium, phosphorous, and total bases, in the mounds and adjacent soil. Thus, the termite activity altered the clay content and most of the soil chemical properties in all of the studied areas, but only for the center of the mounds. However, the effect of these organisms was different in the eucalyptus plantation in relation to the pasture areas.

scholarly journals Using Multivariate Geostatistics to Assess Patterns of Spatial Dependence of Apparent Soil Electrical Conductivity and Selected Soil Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Glécio Machado Siqueira ◽  
Jorge Dafonte Dafonte ◽  
Montserrat Valcárcel Armesto ◽  
Ênio Farias França e Silva
Keyword(s):  
Electrical Conductivity ◽  
Soil Properties ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Clay Content ◽  
Data Sets ◽  
Soil Electrical Conductivity ◽  
Multivariate Geostatistics ◽  
Northwestern Spain

The apparent soil electrical conductivity (ECa) was continuously recorded in three successive dates using electromagnetic induction in horizontal (ECa-H) and vertical (ECa-V) dipole modes at a 6 ha plot located in Northwestern Spain. One of the ECadata sets was used to devise an optimized sampling scheme consisting of 40 points. Soil was sampled at the 0.0–0.3 m depth, in these 40 points, and analyzed for sand, silt, and clay content; gravimetric water content; and electrical conductivity of saturated soil paste. Coefficients of correlation between ECaand gravimetric soil water content (0.685 for ECa-V and 0.649 for ECa-H) were higher than those between ECaand clay content (ranging from 0.197 to 0.495, when different ECarecording dates were taken into account). Ordinary and universal kriging have been used to assess the patterns of spatial variability of the ECadata sets recorded at successive dates and the analyzed soil properties. Ordinary and universal cokriging methods have improved the estimation of gravimetric soil water content using the data of ECaas secondary variable with respect to the use of ordinary kriging.

Superphosphate and stocking rate effects on a native pasture oversown with Stylosanthes humilis in central coastal Queensland. 3. The balance of native species in the pasture

1978 ◽  
Vol 18 (95) ◽  
pp. 808 ◽  
Author(s):  
NH Shaw ◽  
MB Dale
Keyword(s):  
Native Species ◽  
Floristic Composition ◽  
Exchange Capacity ◽  
Response To Treatment ◽  
Data Sets ◽  
Heteropogon Contortus ◽  
Native Pasture ◽  
Total Exchange Capacity ◽  
Highly Correlated ◽  
Stocking Rates

The percentage frequency of all herbaceous species in a native pasture oversown with S. humilis (T.S.) was measured at the beginning and end of an eight-year grazing experiment. Treatments imposed were three levels of molybdenized superphosphate (nil; 125 kg ha-1 annually; 250 kg ha-1 annually plus an extra 250 kg ha-1 initially) in factorial combination with four stocking rates and two sowing methods for T.S. (ground sowing into spaced cultivated strips or aerial sowing). Stocking rates were gradually increased during the experiment and for the last three years overlapping ranges were used for the three fertilizer levels; the overall range was then from 0.55 to 1.65 beast ha-1. Treatments did not induce any major changes in the proportions of native species in the pasture. Heteropogon contortus remained dominant and its frequency increased in all treatments. Of the total of 113 species recorded, only 18 reached 10 per cent frequency in at least one paddock on one occasion. Several of these showed statistically significant changes in response to treatment, but their relative importance was not greatly changed. Examination of the results by principal co-ordinate and canonical analysis, showed that the first vectors of the two data sets were highly correlated, indicating that the major control on floristic composition was not changed by oversowing with T.S. or by the treatments imposed. Treatment effects dominated in the second and third vectors in the final year. The controlling vector was found to be highly correlated with soil calcium, potassium, total exchange capacity and organic carbon, but the basis for the correlations remains undetermined.

scholarly journals Relationship of soil properties to fractionation, bioavailability and mobility of lead and zinc in soil

2008 ◽  
Vol 53 (No. 5) ◽  
pp. 225-238 ◽  
Author(s):  
N. Finžgar ◽  
P. Tlustoš ◽  
D. Leštan
Keyword(s):  
Organic Matter ◽  
Regression Analysis ◽  
Soil Organic Matter ◽  
Soil Properties ◽  
Multiple Regression ◽  
Contaminated Soils ◽  
Organic Matter Content ◽  
Clay Content ◽  
Exchange Capacity ◽  
Matter Content

Sequential extractions, metal uptake by <i>Taraxacum officinale</i>, Ruby&rsquo;s physiologically based extraction test (PBET) and toxicity characteristic leaching procedure (TCLP), were used to assess the risk of Pb and Zn in contaminated soils, and to determine relationships among soil characteristics, heavy metals soil fractionation, bioavailability and leachability. Regression analysis using linear and 2nd order polynomial models indicated relationships between Pb and Zn contamination and soil properties, although of small significance (<i>P</i> < 0.05). Statistically highly significant correlations (<i>P</i> < 0.001) were obtained using multiple regression analysis. A correlation between soil cation exchange capacity (CEC) and soil organic matter and clay content was expected. The proportion of Pb in the PBET intestinal phase correlated with total soil Pb and Pb bound to soil oxides and the organic matter fraction. The leachable Pb, extracted with TCLP, correlated with the Pb bound to carbonates and soil organic matter content (<i>R</i><sup>2</sup> = 69%). No highly significant correlations (<i>P</i> < 0.001) for Zn with soil properties or Zn fractionation were obtained using multiple regression.

Sign in / Sign up

Export Citation Format

Share Document