Zeta potential of porous rocks in contact with mixtures of monovalent and divalent electrolytes
L.D. Thanh, R. Sprik and X.C. Nguyen
Journal name: Geophysical Prospecting
Issue: Vol 67, No 5, June 2019 pp. 1354 - 1368
Info: Article, PDF ( 2.62Mb )
The zeta potential is one of the most important parameters influencing the electroki-netic coupling. Most reservoir rocks are saturated or partially saturated by natural water containing various types of ions (mostly monovalent and divalent ions). There-fore, understanding how the zeta potential behaves for mixtures of electrolytes is very important. In this work, measurements of the zeta potential for four different silica-based samples saturated by seven different mixtures of monovalent and divalent electrolytes are then carried out at a fixed ionic strength. It is seen that the magnitude of the measured zeta potential decreases with increasing divalent cation fraction. The experimental results are then explained by a model developed for mixtures of mono-valent and divalent electrolytes. The result shows that the theoretical model is able to reproduce the main trend of the variation of the zeta potential with divalent cation fractions. Additionally, the model can fit the experimental data reported in literature well for reasonable values of the input parameters.