- Article
Authors: Luong, Duy Thanh (2018) - A model for the effective excess charge in a capillary as well as in porous media is developed for arbitrary pore scales. The prediction of the model is then compared with another published model that is limited for a thin electric double layer (EDL) assumption. The comparison shows that there is a deviation between two models depending on the ratio of capillary/pore radius and the Debye length. The reasons for the deviation between two models are not only due to the thin EDL assumption to get electrical potential and charge distribution in pores but also to some other approximations for integral evaluations. The results suggest that the model developed in this work can be used...
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- Article
Authors: Luong, Duy Thanh (2019) - In this work, the fractal model for the streaming potential coefficient in porous media recently published has been examined by calculating the zeta potential from the measured streaming potential coefficient. Obtained values of the zeta potential are then compared with experimental data. Additionally, the variation of the streaming potential coefficient with fluid electrical conductivity is predicted from the model. The results show that the model predictions are in good agreement with the experimental data available in literature. The comparison between the proposed model and the Helmholtz-Smoluchowski (HS) equation is also carried out. It is seen that the prediction from the propos...
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- Article
Authors: Luong, Duy Thanh; Rudolf, Sprik (2016) - Electrokinetic phenomena are induced by the relative motion between a fluid and a solid surface and are directly related to the existence of an electric double layer between the fluid and the solid grain surface. Electrokinetics in porous media plays an important role in geophysical applications and environmental applications. Electrokinetic phenomena depend not only on fluid but also on microstructure parameters of porous media. In order to study the dependence of electrokinetics on microstructure parameters, we have measured the microstructure parameters as well as elastic moduli of 21 porous rock samples including natural rocks and artificial rocks. The experimental results are in ...
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- Article
Authors: Luong, Duy Thanh; Rudolf, Sprik (2018) - The streaming potential coefficient of liquid-rock systems is theoretically a very complicated function depending on many parameters including temperature, fluid concentration, fluid pH, as well as rock parameters such as porosity, grain size, pore size, and formation factor etc. At a given porous media, the most influencing parameter is the fluid conductivity or electrolyte concentration. Therefore, it is useful to have an empirical relation between the streaming potential coefficient and electrolyte concentration. In this work, the measurements of the streaming potential for four unconsolidated samples (sandpacks) saturated with four monovalent electrolytes at six different electrol...
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- Article
Authors: Luong, Duy Thanh; Rudolf, Sprik (2017) - Streaming potential is induced by the relative motion between a fluid and a solid surface and is directly related to the existence of an electric double layer between the fluid and the solid grain surface. Streaming potential depend not only on the fluid and mineral composition of rocks but also on microstructure parameters of rocks. To investigate the variation of streaming potential with rock parameters including the effects of the variation of the zeta potential due to the difference in mineral compositions between samples, we perform streaming potential measurements on six samples of Berea sandstone saturated with four different NaCl solutions. The results show that the streaming ...
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- Journal Article
Authors: Pham, Thi Thu Ha; Vu, Xuan Hoa; Trinh, Dinh Kha; Nguyen, Dac Dien; Luong, Duy Thanh; Nguyen, Quang Hung; Luong, Van Luyen (2021) - -
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- Article
Authors: Luong, Duy Thanh (2017) - The measurements of the zeta potential of five consolidated samples including natural and artificial ceramic rocks saturated with 5.0×10-3 M NaCl electrolyte at different temperatures have been reported. The zeta potential obtained in this work is always negative and increases in magnitude with increasing temperature for all samples (an average increase of the zeta potential of 0.4 mV/ oC in magnitude). The experimental results are in good agreement with previously published data. The experimental data is then explained by a theoretical model. It is shown that the model is able to reproduce the main trend of the experimental data from our work and from published articles.
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- Article
Authors: Luong, Duy Thanh (2018) - Theoretical models have been developed to calculate the zeta potential based on the solution of the linearized approximation of the Poisson-Boltzmann equation (PB). The approximation is only valid for the small magnitude of the surface potential. However, the surface potential available in published experimental data normally does not satisfy that condition. Therefore, the complete analytical solution to the PB equation (nonlinear equation) needs to be considered. In this work, the comparison between the linearized and nonlinear solutions has been performed. The results show that the linearized solution always overestimates the absolute value of the electric potential in the electric ...
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- Article
Authors: Luong, Duy Thanh (2018) - Measurements of the zeta potential in sandpacks saturated with monovalent electrolytes at six different electrolyte concentrations have been reported. The values we record are classified into two groups based on the magnitude of the zeta potential: group 1 (samples S1 and S2) and group 2 (samples S3 and S4). The measured zeta potential in magnitude in group 1 is much smaller than that in group 2 and in literature at the same electrolyte concentration. The reason for a big variation of the zeta potential between group 1 and group 2 may be due to the difference in technique of making sand particles of different size leading to change of particle surface properties. Consequently, the zet...
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- Article
Authors: Luong, Duy Thanh; Rudolf, Sprik (2015) - The zeta potential of a solid-liquid interface in porous media is an important surface characterization quantity for geophysical applications or environmental applications, for example. The zeta potential in porous media is normally measured by some techniques such as streaming potential, streaming current. In this work, we use electroosmosis to measure the zeta potential for consolidated porous samples including natural and artificial rocks saturated with NaCl solutions. The measurements show that the values of the zeta potential deduced from our electroosmosis measurements are always smaller than those of the corresponding samples deduced from the reliable streaming potential measur...
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- Article
Authors: Luong, Duy Thanh; Sprik, Rudolf (2015) - Electrokinetic phenomena are induced by the relative motion between a fluid and a solid surface and are directly related to the existence of an electric double layer between the fluid and the solid grain surface. Electrokinetics in porous media plays an important role in geophysical applications and environmental applications. The zeta potential is one of the key parameters in electrokinetics. The zeta potential of liquid-rock systems depends on many parameters such as mineral composition of rocks, fluid properties etc. Therefore, the zeta potential is different for various rocks and liquids. In order to measure the zeta potential for fluid saturated porous rocks, streaming potential ...
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