The study presents the results of comprehensive experimental investigations of the rheological properties, stability, flow behavior, and destruction of water-in-oil emulsions based on the emulsifier KR-3E grade B and hydrophobic silicon dioxide Orisil M300. The influence of the aqueous phase composition (tap water, calcium chloride solution with a density of 1,15 g/cm3 widely used in well servicing and downhole operations, and their 1:1 mixture) and the concentration of silicon dioxide nanoparticles (0,3, and 5 wt % relative to the hydrocarbon phase) on the key parameters of the emulsion systems was examined. It was established that silicon dioxide acts as an effective thickening agent, significantly increasing the viscosity and stability of the emulsions, particularly in saline environments. Emulsions based on CaCl2 solutions containing 3-5 % of SiO2 nanoparticles demonstrated exceptional thermal stability (showing no phase separation for more than 95 hours at 90 °C) and a time-dependent increase in viscosity. At the same time, such formulations lost flowability at room temperature, which complicates their injection into wells. The most pronounced viscosity-reducing effect on the resulting emulsions was observed for the multipurpose hydrocarbon solvent KR-4R, which proved effective in wellbore treatments. It is shown that using a mixture of tap water and calcium chloride solution enables the formation of Pickering emulsions with an optimal balance of rheological properties and stability, stabilized by solid silicon dioxide nanoparticles.
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