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Chemical Flooding 199
Figure 6.8 Pickering emulsion formation in presence of nanoparticles and polymer [88].
considerably higher oil recovery compared to conventional water injection [88]. Fig. 6.8
depicts the graphical demonstration of Pickering emulsion generated by surfactant, nano-
particles, and polymer. Afzali Tabar et al. [89] proposed a new method for preparing
Pickering emulsions using graphene/silica nanoparticles. Their experimental results
showed that graphene nanoparticles could improve the performance of Pickering emul-
sion in terms of rheological behavior in comparison with other conventional nanoparti-
cles. However, they did not use real oil sample in conduction of experiments.
Another application of nanoparticles for EOR purposes is improving the perfor-
mance of surfactant in wettability alteration of oil reservoirs, particularly carbonates,
from oil-wet toward water-wet or neutral-wet conditions. Nwidee et al. [90] studied
the effect of nanoparticle and surfactant on the rock wettability using contact angle
measurement, imbibition test as well as morphological experiments. They concluded
that combination of nanoparticle and surfactant could be able to change reservoir
rock wettability; take this advantage for improving the oil recovery factor or employ-
ing in decontamination of soils [90].
Ahmadi [91] conducted batch adsorption tests along with core-flooding experi-
ments using an ionic surfactant (SDS) and nanosilica. He employed real sandstone
core samples in his experiments. Based on the experimental results he concluded that
adding nanosilica could improve considerably the oil recovery factor of SDS; he main-
tain this incremental oil is due to reduction of surfactant adsorption [91]. Ahmadi and
Sheng [92] studied experimentally the flooding efficiency of nanosurfactant in carbon-
ate core samples. They used nanosilica and SDS in their tests. They concluded that
adding nanosilica increases the efficiency of SDS in oil recovery due to reduction of
