Experimental Characterization of Dielectric Properties in Fluid Saturated Artificial Shales

Abstract

High dielectric contrast between water and hydrocarbons provides a useful method for distinguishing between producible layers of reservoir rocks and surrounding media. Dielectric response at high frequencies is related to the moisture content of rocks. Correlations between the dielectric permittivity and specific surface area can be used for the estimation of elastic and geomechanical properties of rocks. Knowledge of dielectric loss-factor and relaxation frequency in shales is critical for the design of techniques for effective hydrocarbon extraction and production from unconventional reservoirs. Although applicability of dielectric measurements is intriguing, the data interpretation is very challenging due to many factors influencing the dielectric response. For instance, dielectric permittivity is determined by mineralogical composition of solid fraction, volumetric content and composition of saturating fluid, rock microstructure and geometrical features of its solid components and pore space, temperature, and pressure. In this experimental study, we investigate the frequency dependent dielectric properties of artificial shale rocks prepared from siltclay mixtures via mechanical compaction. Samples are prepared with various clay contents and pore fluids of different salinity and cation compositions. Measurements of dielectric properties are conducted in two orientations to investigate the dielectric anisotropy as the samples acquire strongly oriented microstructures during the compaction process.

Laboratory dielectric measurements to evaluate the conductivity change in the presence of chelating agent with different brines

“…In a study by Beloborodov et al 15 they concluded that at high frequencies (above 10 MHz) real relative permittivity will show a different linear trend with porosity in fresh water and brine saturated samples. The showed that salinity and cation composition of the pore fluid have a negligible effect on dielectric measurements at high frequency.…”

Relaxor-Ferroelectric Films for Dielectric Tunable Applications: Effect of Film Thickness and Applied Electric Field

“…In general, the decrease in the dielectric constant with increase in frequency could be attributed to the contribution of various effects, such as electronic polarization (occurs at frequencies up to 10 13 kHz), ionic polarization (up to 10 10 kHz), dipolar polarization (up to 10 7 kHz) and space-charge polarization (up to 10 2 kHz) [ 55 , 56 ]. Higher values of dielectric constant at low frequency are due to the contribution of all the various types of polarizations in the capacitors.…”

Clay Mineral Type and Content Control Properties of Fine-Grained CO2 Caprocks—Laboratory Insights from Strongly Swelling and Non-Swelling Clay–Quartz Mixtures

“…As Figure 7 demonstrates, the majority of published kaolinite compaction curves document 17-25% total porosity at 50 MPa effective vertical stress [23,26,[55][56][57][58][59][60][61][62][63]. The coarser kaolinite grains were more susceptible to compaction (more compressible) than the finer kaolinites.…”

“…The second inconsistency was found in recognizing maximum compaction in argillaceous deposits. A (majority) group of experimental studies showed that the highest compaction level and maximum porosity loss could be identified for brine-saturated quartz-clay mixtures with 20-40% kaolinite content (and 60-80% quartz) [26,55,59,[64][65][66][67][68][69][70][71]. These experimental works have reported a total porosity of around 12% at 50 MPa effective vertical stress for such mixtures.…”

“…Our compaction experiments contradict the latter group's claim that the highest compaction is associated with pure kaolinite and confirms that only the best packing of a kaolinite-quartz mixture may show the lowest attainable total porosity or highest The second inconsistency was found in recognizing maximum compaction in argillaceous deposits. A (majority) group of experimental studies showed that the highest compaction level and maximum porosity loss could be identified for brine-saturated quartz-clay mixtures with 20-40% kaolinite content (and 60-80% quartz) [26,55,59,[64][65][66][67][68][69][70][71]. These experimental works have reported a total porosity of around 12% at 50 MPa effective vertical stress for such mixtures.…”