Kazemzadeh, Yousef (Department of Petroleum Engineering, Amirkabir University of Technology, Tehran Polytechnic) | Ismael, Ismael (Department of Petroleum Engineering, School of Chemical and Petroleum Engineering, Shiraz University) | Rezvani, Hosein (Department of Mining Engineering, Isfahan University of Technology) | Sharifi, Mohammad (Department of Petroleum Engineering, Amirkabir University of Technology, Tehran Polytechnic) | Riazi, Masoud (Enhanced Oil Recovery, Research Centre, IOR EOR Research Institute, Shiraz University, Shiraz, Iran Department of Petroleum Engineering, School of Chemical and Petroleum Engineering, Shiraz University)
Type of emulsification is dependent on several factors, including chemical composition of crude oil, type of surface active agents, oil and water volume percentages, and type of emulsification. The water present in oil reservoirs, including connate water and injected water, can highly affect the formation and stability of the emulsions. Injection of smart water (water containing certain weight percentage of various ions) and nanofluids (nanoparticles-dispersed water-based fluids) are effective on the emulsion formation and stabilization. NaCl and MgCl2 are among the common irrefutable salts in enhanced oil recovery (EOR) methods. Analysis of the formation and stabilization of emulsions is fulfilled with different methods. Investigation of morphology of water and oil droplets is considered as a static method of analyzing the emulsion stability. In this study, the average area of water droplets in the oil phase has been calculated. The study has been continued with the static analysis of emulsion stability by monitoring the emulsion resistance to phase separation. Regarding increased viscosity with emulsification, the emulsified fluids were developed during tertiary injection of nanofluid and smart water and the ultimate oil recoveries were monitored. The effect of salt type and concentration on the formation and stabilization of emulsions has been also investigated. Based on the previous studies performed by the research group, Fe3O4-based nanocomposites play an important role in the formation and stabilization of emulsions. Accordingly, different concentrations of Fe3O4/Chitosan nanocomposites were used in this study. Finally, an evaluation was performed on comparing the performance of smart water and nanofluid injection at the optimum concentrations. 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 smart water and nanofluid showed that the emulsions developed during nanofluid injection were more stable and in turn recorded a higher oil recovery.