An experimental study toward possible benefits of water in oil emulsification in heavy oil reservoirs: Comparing role of ions and nanoparticles

The current study presents a comparison between tertiary injection of smart water (MgCl₂ and NaCl brines) and nanofluid (Fe₃O₄ and Fe₃O₄/Chitosan) with a focus on the effect of water in heavy oil emulsification on the oil production. For this purpose, seawater (as a secondary injection fluid) and various concentrations of nanofluids and brines (as tertiary injection fluids) were injected into a carbonate sand pack. The produced fluid (oil + water) was separated by centrifugal force and the oil/water ratio was determined, which was then used in preparing different water in oil emulsions. The emulsions were then analyzed. The ultimate oil recoveries were monitored during tertiary injection of certain nanofluids and smart waters and were discussed from the perspective of emulsion resistance to the phase separation. The effect of salt type and concentration of salt and Fe₃O₄/Chitosan nanocomposites was investigated on the formation and stabilization of emulsions. Finally, the performance of smart water and nanofluid injection at the optimum concentrations were compared. According to the results obtained, 10000 ppm MgCl₂ presented the best performance in the formation and stabilization of the emulsions as compared to the other concentrations. The synthesized nanocomposite also showed the best result at 0.05 wt%. Comparing the emulsification in smart water and nanofluid revealed that the emulsions developed during nanofluid injection were more stable and therefore led to a higher oil recovery factor.