Geophysical research: article

Аnnotation: The influence of direct current in sandstone samples on the filtration of aqueous suspensions of NaCl, KCl, citric acid, and colloidal solution with aluminum oxide nanoparticles (nanofluids) was experimentally studied in this paper. The studies were performed using cores of quartz-feldspar sandstone (diameter 30, length 60 mm), porosity 13-15 %, grain size 0.5-1.5 mm. High porosity allowed the solution filtration at atmospheric pressure. Sandstone samples in a heat shrink tube were fixed vertically on the bracket. Platinum mesh electrodes were installed at the ends of the cores, through which a solution was passed through the sample. Most of the experiments were carried out with sequential stepwise increase in voltages in the range of 12-100 V. Each sample was preliminarily saturated with a solution of a given composition, and the saturation was constant throughout the whole experiment. Further, time during which a fixed solution volume - one, five and ten drops - filtered through the sample at a given voltage was measured. Then the voltage was reduced to zero, and the cycle was repeated at a higher voltage. We used various fluid compositions (suspensions) with different concentration of components from 0.0025 to 0.02 %. The main solvents were distilled and natural water, to which citric acid, nanosized Al