An anisotropic model for the electrical resistivity of two-phase geologic materials


Ellis, Michelle H., Sinha, Martin C., Minshull, Tim A., Sothcott, Jeremy and Best, Angus I. (2010) An anisotropic model for the electrical resistivity of two-phase geologic materials. Geophysics, 75, (6), E161-E170. (doi:10.1190/1.3483875).

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Description/Abstract

Electrical and electromagnetic surveys of the seafloor provide valuable information about the macro and microscopic properties of subseafloor sediments. Sediment resistivity is highly variable and governed by a wide range of properties including pore-fluid salinity, pore-fluid saturation, porosity, pore geometry, and temperature. A new anisotropic, twophase, effective medium model describes the electrical resistivity of porous rocks and sediments. The only input parameters required are the resistivities of the solid and fluid components, their volume fractions and grain shape. The approach makes use of the increase in path length taken by an electrical current through an idealized granular medium comprising of aligned ellipsoidal grains. The model permits both solid and fluid phases to have a finite conductivity useful for dealing with surface charge conduction effects associated with clay minerals and gives results independent of grain size hence, valid for a wide range of sediment types. Furthermore, the model can be used to investigate the effects of grain aspect ratio and alignment on electrical resistivity anisotropy. Good agreement was found between the model predictions and laboratory measurements of resistivity and porosity on artificial sediments with known physical properties.

Item Type: Article
ISSNs: 0016-8033
Subjects: Q Science > QE Geology
Divisions: University Structure - Pre August 2011 > National Oceanography Centre (NERC)
University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
National Oceanography Centre (NERC) > Marine Geoscience
ePrint ID: 173633
Date Deposited: 04 Feb 2011 13:34
Last Modified: 27 Mar 2014 19:21
URI: http://eprints.soton.ac.uk/id/eprint/173633

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