Recent experimental studies on nanoparticles based enhance oil recovery (Nano EOR) have shown that silica nanoparticles have great ability to form Pickering emulsion, thereby increasing the ultimate oil recovery. However, the main challenge is to stabilize silica nanoparticles in reservoir's harsh conditions. Azadgoleh et.al. (2014) found that the use of anionic surfactant can increase the stability of nanofluid by imparting steric hindrance to the silica nanoparticles. In order to analyze the effectiveness of Nano EOR, it is critical to study the in-situ emulsion formation capability of stabilized silica nanoparticle in presence of surfactant especially.

Water in oil micro emulsion studies were carried out for two different types of crude oil i.e. light oil and paraffinic oil. For each crude oil, nanofluid were prepared by dispersing 0.05wt% silica nanoparticles in synthetic brine (NaCl) of different five salinities (0.1 wt.%, 0.5 wt.%, 1 wt.%, 2 wt.% and 3 wt. %). Anionic surfactant (sodium dodecyl sulphonate) with concentration equal to 0.05wt% was added to the prepared nanofluid for increasing its stability. To carry out the micro emulsion phase behavior study, the water-oil ratio was kept to 1; temperature was kept at 80°C and the phase volume measurements were carried for 5 days. The outputs were compared with the emulsion study in presence of only silica nanoparticles and with only surfactant by employing the similar process.

The results show that nanofluid consisting of only silica nanoparticles have a great tendency to form micro emulsion as compared to solutions consisting of only surfactant and nanofluid containing nanoparticles + surfactant for a fixed concentration of 0.05 wt.%. When compared with pure surfactant based micro emulsion study, it was observed that relatively less concentration of silica nanoparticle will be required to form emulsion. The processes and results are outlined and discussed in detailed in the paper.

This study is useful to understand the behavior of silica nanoparticles in forming Pickering emulsion in presence of anionic surfactant and the frontier of using nanoparticle as a potential EOR method before applying to the field scale.

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