Low-frequency complex conductivity of sandy and clayey materials
A Revil1, J D Eppehimer, M Skold
1Colorado School of Mines, Department of Geophysics, Golden, CO 80401, USA. arevil@mines.edu
Journal of Colloid and Interface Science
|March 16, 2013
Summary
This study reveals that Stern layer polarization governs low-frequency conductivity in sands and sandstones. The developed model accurately predicts complex conductivity in various clayey materials and silica sands.
Area of Science:
- Geophysics
- Materials Science
- Electrochemistry
Background:
- Low-frequency electrical polarization in porous media is primarily influenced by the Stern layer.
- Understanding this phenomenon is crucial for characterizing geological materials like sands and sandstones.
Purpose of the Study:
- To investigate a model of Stern layer polarization coupled with surface complexation.
- To predict the complex conductivity of clayey materials and silica sands based on their properties and pore water chemistry.
Main Methods:
- Development of a simple Stern layer polarization model combined with a surface complexation model.
- Experimental measurements of complex conductivity (1 mHz-45 kHz) on well-characterized saprolites and sandstones.
- Validation of the model using new experimental data and existing literature data.
Main Results:
- The model successfully predicts complex conductivity as a function of porosity, cation exchange capacity (or specific surface area), and salinity.
- Excellent agreement was found between model predictions and experimental data for both clayey and clay-free materials.
- The study demonstrates the applicability of the model to natural clayey materials and silica sands.
Conclusions:
- The Stern layer polarization model provides an accurate method for predicting the low-frequency complex conductivity of sands and sandstones.
- This model can be a valuable tool for geophysical exploration and subsurface characterization.
- The findings highlight the significant role of the Stern layer in the electrical properties of porous geological media.
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