Ali Maghzi - Chemical and Petroleum Engineering Department, Sharif University of Technology, Tehran, Iran
Saber Mohammadi - Chemical and Petroleum Engineering Department, Sharif University of Technology, Tehran, Iran
Mohammad Hossein Ghazanfari - Chemical and Petroleum Engineering Department, Sharif University of Technology, Tehran, Iran
Mohsen Masihi - Chemical and Petroleum Engineering Department, Sharif University of Technology, Tehran, Iran

It is well known that the displacement efficiency of EOR processes is mainly affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of pores surfaces has remained a topic of debate in the literature. Furthermore, a little is known about howthe dispersed silica nanoparticles affect the microscopic/macroscopic recovery efficiency of heavyoils during common immiscible processes such as water flooding. In this study, a series ofinjection experiments was performed on five-spot glass micromodel which is initially saturated with the heavy oil. Distilled water and dispersed silica nanoparticles in water (DSNW) at different values of weight percent were used as injected fluids. The macroscopic efficiency as well as fluiddistribution in the pores and throats was monitored from analysis of continuously provided pictures during the experiments. Contact angles of the glass surfaces at different conditions ofwettability were measured by using sessile drop method when the glass surfaces coated by heavyoil, distilled water and the solutions of DSNW. The results revealed that the silica nanoparticles caused enhancement of sweep efficiency during water flooding and this enhancement wasintensified by increasing the silica nanoparticles percent in water. And also, ultimate efficiency forDSNW (0.1%w) flooding increased by a factor of 8.7% in comparison to distilled water flooding. This increment in oil recovery was reached to 26% by increasing silica nanoparticles weight percent from 0.1%w to 3%w. The distribution of DSNW solution during flooding tests in pores and throats showed strong water-wet condition after flooding with high concentration of nanosolution. The results of sessile drop experiments showed that coating with heavy oil, could make an oil-wet surface. While, coating with distilled water could partially alter the wettability ofsurface to water-wet and coating with high concentration of DSNW could make a strongly waterwet surface. The hydrophilic nature of selected silica nanoparticles is responsible for wettability alteration of the micromodel from oil-wet to water-wet. Results of this work disclose the effect ofsilica nanoparticles on wettability alteration of pores surfaces as well as on enhancement of icroscopic/macroscopic efficiency during DSNW flooding to heavy oils.

Wettability Alteration, Dispersed Silica Nanoparticles, Heavy Oil Recovery, Five-Spot Micromodel, Water Flooding