DETERMINATION OF CLAY CONTENT AND ASSESSMENT OF THE MINERALOGICAL and chemical COMPOSITION OF TERRIGENOUS SEDIMENTARY ROCKS BY THE DIELECTRIC METHOD
A.V. Repin1, P.P. Bobrov1,2, N.A. Golikov3, O.V. Rodionova1
1Omsk State Pedagogical University, Omsk, Russia
2 Institute of Radiophysics and Physical Electronics of the Scientific Center of the Siberian Branch of the Russian Academy of Sciences, Omsk, Russia
3 Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Dielectric constant, resonator method, NMR, sandstones, siltstones, clay minerals, clay content, mineral composition, chemical composition.
Abstract
The paper presents the results of permittivity measurements for loose dry sand and clay minerals in the frequency range of 0.5–2 GHz. A coaxial cell, a half-wave resonator, and a ZNB20 vector network analyzer were used for the measurements. Using a dielectric mixture model, the permittivity of the solid phase of minerals was found. The permittivity of 12 solid samples of sand and siltstone rocks was measured in a capacitor cell in the frequency range of 100–500 MHz. The method for estimating the proportion of clay minerals in solid samples is based on differences in the permittivity of sand (3.8–5) and clay minerals (7.5–11) and the use of a dielectric mixture model. The rock was initially considered as a two-phase medium containing air and a solid phase, then the solid phase was considered as a mixture of sand and clay fractions. The clay content values found using the dielectric method were compared with the results obtained using the NMR method. Permittivity and density data were used to assess the mineral composition of the samples. Taking into account the chemical composition of the minerals and their content determined by the dielectric method, the contents of the main chemical elements in six samples were estimated and compared with the results obtained by scanning electron microscopy.
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