Dependence of the Electrical Conductivity on Saturation in Real Porous Media

Ewing, Robert P.; Hunt, A. G.

doi:10.2136/vzj2005.0107

Cited by 116 publications

(108 citation statements)

References 69 publications

(166 reference statements)

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“…To evaluate the relationship between physical properties and fault rock distribution, we made cross-plots between the logs and fracture density. We also used cross-plots of neutron porosity and resistivity to determine the pore structure, connectivity of the cracks, percolation thresholds, and hydrologic properties (e.g., Ewing and Hunt 2006;Montaron 2009;Kozlov et al 2012) along the Nobeoka Thrust. The approximate correlation between porosity and resistivity is empirically known as Archie's law (Archie 1942), which is formulated as:…”

Section: Data Acquisition and Methodology For Core-log Integrationmentioning

confidence: 99%

Multiple damage zone structure of an exhumed seismogenic megasplay fault in a subduction zone - a study from the Nobeoka Thrust Drilling Project

et al. 2015

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To investigate the mechanical properties and deformation patterns of megathrusts in subduction zones, we studied damage zone structures of the Nobeoka Thrust, an exhumed megasplay fault in the Kyushu Shimanto Belt, using drill cores and geophysical logging data obtained during the Nobeoka Thrust Drilling Project. The hanging wall, composed of a turbiditic sequence of phyllitic shales and sandstones, and the footwall, consisting of a mélange of a shale matrix with sandstone and basaltic blocks, exhibit damage zones that include multiple sets of 'brecciated zones' intensively broken in the mudstone-rich intervals, sandwiched by 'surrounding damage zones' in the sandstone-rich intervals with cohesive faults and mineral veins. The fracture zones are thinner (2.7 to 5.5 m) in the sandstone-rich intervals and thicker in the shale-dominant intervals (2.3 to 18.6 m), which indicates a preference of coseismic slip and velocity-weakening in the former, and aseismic deformation in the latter. However, the surrounding damage zones observed in the current study are associated with an increase in resistivity, P-wave velocity, and density and a decrease in porosity, inferring densification and strain-hardening in the sandstone-rich intervals and strain-weakening in the mudstone-rich intervals. These observations indicate that the sandstone-rich damage zones may weaken in the short term but may strengthen in the geologically long term, contributing to a later stage of fault activity. In contrast, the mudstone-rich damage zones may strengthen in the short term but develop weak structures through longer time periods. The observed shear zone thickness in the hanging wall is thinner (2.3 to 18.6 m) compared to the footwall damage zones (12 to 39.9 m), possibly because faults in the hanging wall were concentrated and partitioned between the preexisting turbiditic sequence of alternating shale/ sandstone-dominant intervals, whereas in the footwall, faults were more sporadically distributed throughout the sandstone block-in-matrix cataclasites. A splay fault may evolve and be characterized by physical property contrasts, the lithology dependence of deformation, and the variability of damage zone thickness due to a heterogeneous lithology distribution in the hanging wall and footwall. The deformation patterns observed in the Nobeoka Thrust provide insights to the strain-hardening/weakening behaviors of sediments along megathrusts over geological timescales.

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Section: Data Acquisition and Methodology For Core-log Integrationmentioning

confidence: 99%

Multiple damage zone structure of an exhumed seismogenic megasplay fault in a subduction zone - a study from the Nobeoka Thrust Drilling Project

et al. 2015

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“…The ERT data are sensitive to the subsurface geoelectrical structure, which is in turn sensitive to subsurface variations in water saturation and pore water salinity ͑Ar-chie, 1942; Mualem and Friedman, 1991;Henry, 1997;Ewing and Hunt, 2006͒. This makes ERT particularly useful for characterizing infiltration into bedrock where conventional methods of soil moisture accounting fail.…”

Section: Introductionmentioning

confidence: 99%

Application of time-lapse ERT imaging to watershed characterization

et al. 2008

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Time-lapse electrical resistivity tomography ͑ERT͒ has many practical applications to the study of subsurface properties and processes. When inverting time-lapse ERT data, it is useful to proceed beyond straightforward inversion of data differences and take advantage of the time-lapse nature of the data. We assess various approaches for inverting and interpreting time-lapse ERT data and determine that two approaches work well. The first approach is model subtraction after separate inversion of the data from two time periods, and the second approach is to use the inverted model from a base data set as the reference model or prior information for subsequent time periods. We prefer this second approach. Data inversion methodology should be considered when designing data acquisition; i.e., to utilize the second approach, it is important to collect one or more data sets for which the bulk of the subsurface is in a background or relatively unperturbed state. A third and commonly used approach to time-lapse inversion, inverting the difference between two data sets, localizes the regions of the model in which change has occurred; however, varying noise levels between the two data sets can be problematic. To further assess the various time-lapse inversion approaches, we acquired field data from a catchment within the Dry Creek Experimental Watershed near Boise, Idaho, U.S.A. We combined the complimentary information from individual static ERT inversions, time-lapse ERT images, and available hydrologic data in a robust interpretation scheme to aid in quantifying seasonal variations in subsurface moisture content.

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“…Ewing and Hunt (2006) considered that there will be some solution in dead-end pores and some isolated in connected pores of CBMs under low saturation, which is useless for electrical conduction. In order to exclude this non-conductive solution, the concept of effective saturation was proposed, and the modified Archie law can be expressed as…”

Section: Introductionmentioning

confidence: 99%

A new model for the electrical conductivity of cement-based material by considering pore size distribution

Liang

Zeng

Zhou

et al. 2017

Magazine of Concrete Research

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Electrical conductivity is one of the most important indicators of the durability, impermeability and frost resistance of cement-based materials (CBMs). It is also a main performance parameter for some special CBMs such as insulating concrete and electrically conductive concrete. The aim of this study was to examine the relationship between electrical conductivity and saturation degree of CBMs more deeply by considering the pore size distribution (PSD), which is described in a new way. The distribution of the pore solution (the main conducting medium) in CBMs was analysed by considering the PSD function, the Kelvin equation and theories of capillary and surface adsorption. According to the pore solution distribution and conductivity theory, a conducting tube network model was established. The curves obtained by the proposed model were found to fit the experimental data well. The conducting tube network model was then used to analyse the factors influencing the electrical conductivity of CBMs. The conclusions obtained from this study were that the electrical conductivity of CBMs varies with the relative ratio of large and small pores and the mean value and standard deviation of large pores, and that the electrical conductivity of CBMs is proportional to the pore solution conductivity and porosity of the CBM.

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Dependence of the Electrical Conductivity on Saturation in Real Porous Media

Cited by 116 publications

References 69 publications

Multiple damage zone structure of an exhumed seismogenic megasplay fault in a subduction zone - a study from the Nobeoka Thrust Drilling Project

Multiple damage zone structure of an exhumed seismogenic megasplay fault in a subduction zone - a study from the Nobeoka Thrust Drilling Project

Application of time-lapse ERT imaging to watershed characterization

A new model for the electrical conductivity of cement-based material by considering pore size distribution

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