Heterogeneities of carbonate core plugs can be assessed by different measurements resulting in different interpretations. In this study, dielectric spectroscopy, NMR, and tracer displacement method performed on the same cores reflect different aspects of heterogeneity related to their own characteristic length scales and physics of the measurements, which complement each other in a multiphysical interpretation.

The complex dielectric permittivity measured on carbonate core samples in the reflection mode in the range of 1 MHz to 1 GHz, exhibits a strong difference between the two extremities of the plugs when turning them upside down. The difference between the two extremities is a result of heterogeneity in the rock plug. It can be due to chemical composition, density, porosity, water saturation, presence of cavities, vugs and micro-fractures, crystalline structure and rock lithology, and, distribution of components inside the rock, which is a complex process need to be fully understand. The dielectric heterogeneity is compared with the NMR porosity profile which, in certain cases, indicates cross section averaged porosity heterogeneities along the core-plug axis and correlated with tracer displacement measurement, which characterizes the pore system hydraulic connection and its related heterogeneity.

To complete this "multiphysics" approach, a numerical forward model of the electromagnetic propagation in the core-plugs was performed, focusing on the effect of artificial vugs at different locations inside the core-plug on the electromagnetic propagation patterns.

From dielectrics and NMR profiles, quantitative heterogeneity indexes are proposed and compared, and correlated with tracer displacement measurement. This results in a better characterization of pore system (such as size, distribution, connectivity). A preliminary carbonate rock model taking into account the pore size effect is developed. The cementation factor is inverted from dielectrics dispersion curve measurements, a good match between inversion and laboratory measurements indicates the importance of pore partitioning in carbonates. These laboratory measurements on core plugs can be applied to well-bore measurements combining for instance Array Dielectric Scanner and NMR downhole tools.

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