The equivalent generalised permittivity of a system composed of dielectric spheres in a conductive continuum is calculated. The diffusion effects are taken into account by characterising the continuous phase by its ion charges, mobilities and equilibrium concentrations. The results obtained, which reduce to the Maxwell-Wagner results in the limit of low diffusion at constant conductivity or large dispersion radii, do not agree with those deduced by Bonincontro et al (1980). They show the Maxwell-Wagner approximation always leads to an overestimation of both the dielectric increment and the relaxation time. These differences could be important in some cases of interest.
The dielectric behaviour of a suspension of conducting spherical particles surrounded by insulating shells have been investigated taking diffusive effects into account. The results obtained reduce, in the corresponding limiting cases, to those previously presented by Pauly, Garcia, Trukhan and co-workers. It is shown that diffusive effects are especially important for particles with thin membranes, for which an apparent thickness, always bigger than the real one, is determined.
Carbonate rocks are among the dominant oil reservoir formations. Due to their heterogeneity, their petrophysical properties are difficult to be evaluated. Magnetic Resonance, applied as low-field Nuclear Magnetic Resonance (NMR) or Magnetic Resonance Imaging (MRI), are powerful tools for reservoir characterization. Their basic advantage is the quantitative demarcation of various fluids. In this work we have used MRI methods in order to evaluate the petrophysical properties of carbonate rocks. For this purpose commercial limestone, saturated with deionized water, crude oil and model oil or mixture of water with model oil were used to acquire calculated spin-spin relaxation time (T2) and Diffusion Tensor Imaging (DTI) MRI scans. This leads to the pixel-by-pixel characterization of the rock samples and the quantitative evaluation of the saturation profiles in 3-D space. The proposed MRI techniques offer a new insight in the spatially resolved information of petophysical properties towards better understanding of the fluid-rock matrix interactions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.