1887

Abstract

A model combining low frequency complex conductivity and high frequency permittivity is developed in the frequency range from 1 mHz to 1 GHz. The low frequency conductivity depends on the pore water conductivity and a surface conductivity term that is mostly controlled by the electrical diffuse layer, the outer component of the electrical double layer coating the surface of the clay minerals. The frequency dependence of the effective quadrature conductivity shows three domains. Below a critical frequency fd that depends on the dynamic pore throat size, the quadrature conductivity is frequency dependent. Between fd and a second critical frequency fp, the quadrature conductivity is fairly well described by a plateau. The frequency fd controls the transition between double layer polarization and the effect of the high frequency permittivity of the material. The Maxwell-Wagner polarization is found to be relatively negligible. For a broad range of frequencies below 1 MHz, the effective permittivity exhibits a strong dependence with the cation exchange capacity or the specific surface area. At high frequency, above the critical frequency fd, the effective permittivity reaches a high-frequency asymptotic limit that is controlled by the two Archie's exponent m and n like the low-frequency electrical conductivity. The unified model is compared with various datasets from the literature and is able to explain fairly well a broad number of observations with a very small number of textural and electrochemical parameters, a result that has never been achieved with previous models. We also present results regarding tight gas reservoirs electrical properties including the effect of anisotropy. Finally, we discuss the development of a new technique to weakly couple cross-well tomography to two-phase flow problems for enhanced oil recovery monitoring.

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/content/papers/10.3997/2214-4609-pdb.381.Revil
2013-08-04
2024-03-29
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609-pdb.381.Revil
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