Connecting complex conductivity spectra to mercury porosimetry of sedimentary rocks

Qifei Niu, André Revil

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

The measured spectral-induced polarization (SIP) response of highly porous granular materials can be modeled by upscaling the Nernst-Planck equation for a single grain and performing a convolution product with the particle size distribution. The distribution of relaxation times associated with the polarization of consolidated porous media seems, intuitively, to be controlled by the pore size distribution because of the radius of curvature of the interface between the solid and the pore water. We have explored a mechanistic model connecting the SIP response of consolidated media to mercury injection capillary porosimetry (MICP) data. First, we developed a mechanistic electric double layer (EDL) polarization model for porous media, which considered the polarization of the Stern layer, which was possibly enhanced by the polarization of the diffuse layer and the effect of the pore size distribution. The new model revealed that the relaxation time of porous media such as sandstones could be overestimated if the enhancement of the overall polarization by the diffuse layer was not considered. Second, we have developed an empirical method to obtain the pore size distribution from MICP data by assuming a linear relation between the pore size and the pore throat size using a pore aspect ratio. Then, we compared the measured quadrature conductivities of nine samples with the theoretical quadrature conductivity obtained by convoluting the pore size distribution with the Warburg model. The Warburg model is considered to represent the quadrature conductivity response of a consolidated porous material characterized by an infinitively narrow unimodal pore size distribution coated by an EDL. The position of the peak of the phase was well-reproduced from the MICP data. In addition, the calculated broadness of the phase spectra was usually wellreproduced by convolving the Warburg function with the pore size distribution.

Original languageEnglish
Pages (from-to)E17-E32
JournalGeophysics
Volume81
Issue number1
DOIs
StatePublished - 31 Jan 2015

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