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Physical Explanation of Archie's Porosity Exponent in Granular Materials: A Process‐Based, Pore‐Scale Numerical Study
Niu, Qifei Zhang, Chi
Niu, Qifei
Zhang, Chi
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Abstract
The empirical Archie's law has been widely used in geosciences and engineering to explain the measured electrical resistivity of many geological materials, but its physical basis has not been fully understood yet. In this study, we use a pore‐scale numerical approach combining discrete element‐finite difference methods to study Archie's porosity exponent m of granular materials over a wide porosity range. Numerical results reveal that at dilute states (e.g., porosity ϕ > ~65%), m is exclusively related to the particle shape and orientation. As the porosity decreases, the electric flow in pore space concentrates progressively near particle contacts and m increases continuously in response to the intensified nonuniformity of the local electrical field. It is also found that the increase in m is universally correlated with the volume fraction of pore throats for all the samples regardless of their particle shapes, particle size range, and porosities.
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Date
2018-02-12
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American Geophysical Union
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Keywords
cementation factor, pore throat, particle shape, granular materials, electrical resistivity
Citation
Niu, Q., & Zhang, C. ( 2018). Physical explanation of Archie's porosity exponent in granular materials: A process‐based, pore‐scale numerical study. Geophysical Research Letters, 45, 1870– 1877. https://doi.org/10.1002/2017GL076751