310
U. S. Behera and J. S. Sangwai
surfactant became inactive and drops out from the solution (Negin et al. 2017). The
concentration of surfactant must be more than the critical micelle concentration in
the liquid phase to get the oil solubilized leading to higher production (Hirasaki et al.
2011). In the case of alkyl ethoxy carboxylated nonionic surfactant, ethoxy groups
form a hydrogen bond with water resulting in the decrease in IFT. This indicates that
the different types of surfactants have different effects on the IFT. Various cationic
surfactants of the family belong to CnTAB (Trimethylammoniumbromide) had been
taken to study the impact of IFT on the surfactants. The results were not the same for
all cationic surfactants. It was minimum, i.e., 0.23 mN/m in the presence of C15TAB
and maximum, i.e., 7.6 mN/m for C16TAB. This may be due to the structure of
the surfactants (Kumar et al. 2016). Hence, it can be concluded that all surfactants
have a different impact on the IFT of two fluid phases. This may depend on the
nature, density, and architecture of the two immiscible fluids. IFT can be measured
with the help of a device known as Tensiometer. Pendant drop and Wilhelmy plate
method are the other popular methods carried out in the laboratory should be replaced
by: most popular methods carried out in the laboratory for IFT measurement. A
laboratory study with sodium silicates, sodium phosphates, sodium carbonate, and
sodium hydroxide as additives in the presence of Petro-step petroleum sulfonate
surfactant manufactured by Stepan Corporation reported that interfacial tension of
injected fluid and oil decreases significantly. The effect of alkali on Petro-step 420
surfactant with NaOH of 0.02 and 0.1 wt% found very low IFT values, 0.023 and
0.008 dyne/cm, respectively (Krumrine et al. 1982).
3.1.1 Effect of Silica Nanoparticles
Silica nanoparticles (SiO 2 ) are the most widely used nanoparticles for investigation
by the researchers due to its low cost. SiO 2 nanoparticles have high impact in the
reduction of interfacial tension between formation fluids. It can be measured by
various methods available. Suleimanov et al. (2011) state that to measure IFT, mostly
by pendant drop method is adopted for its accuracy. IFT which was measured in the
above said method between oil and brine was found to be 19mN/m. After the addition
of varying concentrations of silicon dioxide (SiO 2 ) nanoparticles (10–30 nm) injected
in brine, the significant reduction in IFT between oil and brine was observed, i.e.,
8mN/m. This implies that nanoparticles have a good impact on IFT reduction and
hence improve oil recovery. Hendraningrat et al. (2013) studied the effect of silicon
dioxide nanoparticles on the reduction of IFT for oil–brine system. A significant
reduction in IFT of oil–brine system in the presence of SiO 2 NPs (7 nm) was reported
(Fig. 6a). Reduction in IFT of oil–brine system in the presence of nonuniform SiO 2
NPs (10–40 nm) was also investigated. It can be seen from Fig. 6b that there is a
continuous reduction in IFT with increase in concentration of NPs (Kamal et al.
2017). Therefore, it can be concluded that SiO 2 NPs have good impact in reducing
the IFT of oil–brine system.
It has also been observed that with the increase in the size of the particle, the
recovery of oil may decrease due to pore plugging (Fig. 7a) (Almahfood and Bai
2018). On the other hand, the smaller size of nanoparticles (20–30 nm) can increase
electrostatic repulsion force within nanoparticles, which causes higher disjoining
U. S. Behera and J. S. Sangwai
surfactant became inactive and drops out from the solution (Negin et al. 2017). The
concentration of surfactant must be more than the critical micelle concentration in
the liquid phase to get the oil solubilized leading to higher production (Hirasaki et al.
2011). In the case of alkyl ethoxy carboxylated nonionic surfactant, ethoxy groups
form a hydrogen bond with water resulting in the decrease in IFT. This indicates that
the different types of surfactants have different effects on the IFT. Various cationic
surfactants of the family belong to CnTAB (Trimethylammoniumbromide) had been
taken to study the impact of IFT on the surfactants. The results were not the same for
all cationic surfactants. It was minimum, i.e., 0.23 mN/m in the presence of C15TAB
and maximum, i.e., 7.6 mN/m for C16TAB. This may be due to the structure of
the surfactants (Kumar et al. 2016). Hence, it can be concluded that all surfactants
have a different impact on the IFT of two fluid phases. This may depend on the
nature, density, and architecture of the two immiscible fluids. IFT can be measured
with the help of a device known as Tensiometer. Pendant drop and Wilhelmy plate
method are the other popular methods carried out in the laboratory should be replaced
by: most popular methods carried out in the laboratory for IFT measurement. A
laboratory study with sodium silicates, sodium phosphates, sodium carbonate, and
sodium hydroxide as additives in the presence of Petro-step petroleum sulfonate
surfactant manufactured by Stepan Corporation reported that interfacial tension of
injected fluid and oil decreases significantly. The effect of alkali on Petro-step 420
surfactant with NaOH of 0.02 and 0.1 wt% found very low IFT values, 0.023 and
0.008 dyne/cm, respectively (Krumrine et al. 1982).
3.1.1 Effect of Silica Nanoparticles
Silica nanoparticles (SiO 2 ) are the most widely used nanoparticles for investigation
by the researchers due to its low cost. SiO 2 nanoparticles have high impact in the
reduction of interfacial tension between formation fluids. It can be measured by
various methods available. Suleimanov et al. (2011) state that to measure IFT, mostly
by pendant drop method is adopted for its accuracy. IFT which was measured in the
above said method between oil and brine was found to be 19mN/m. After the addition
of varying concentrations of silicon dioxide (SiO 2 ) nanoparticles (10–30 nm) injected
in brine, the significant reduction in IFT between oil and brine was observed, i.e.,
8mN/m. This implies that nanoparticles have a good impact on IFT reduction and
hence improve oil recovery. Hendraningrat et al. (2013) studied the effect of silicon
dioxide nanoparticles on the reduction of IFT for oil–brine system. A significant
reduction in IFT of oil–brine system in the presence of SiO 2 NPs (7 nm) was reported
(Fig. 6a). Reduction in IFT of oil–brine system in the presence of nonuniform SiO 2
NPs (10–40 nm) was also investigated. It can be seen from Fig. 6b that there is a
continuous reduction in IFT with increase in concentration of NPs (Kamal et al.
2017). Therefore, it can be concluded that SiO 2 NPs have good impact in reducing
the IFT of oil–brine system.
It has also been observed that with the increase in the size of the particle, the
recovery of oil may decrease due to pore plugging (Fig. 7a) (Almahfood and Bai
2018). On the other hand, the smaller size of nanoparticles (20–30 nm) can increase
electrostatic repulsion force within nanoparticles, which causes higher disjoining