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R. M. Jadhav and J. S. Sangwai
the best ways to obtain high recovery of heavy oil. However, there are other methods
that involve the use of injecting miscible gases and uses of solvents to treat heavy oil
have also seen a rise in the production of heavy oil.
4.2.1 Nanoparticle Stabilized Miscible Flooding
Miscible flooding operations and their impact are entirely dependent on the changes
in interfacial tension of the oil, reservoir rocks and the miscibility of the gas with
oil. Miscible gases cause swelling of oil which helps the oil inside pores to flow
more easily and allow better recovery. The arrangement of particles at the interface
controls the strength of the interfacial tension (IFT). IFT reduction is crucial for
processes such as miscible injections. The applicability of metal oxide nanoparticles
has pronounced effects on the IFT in the CO 2 injection process for heavy oil and
CO 2 upgrading systems. CO 2 injection is an effective mechanism to reduce IFT in
heavy oil systems. CO 2 dissolution also helps in lowering the viscosity of heavy
oils (Hu et al. 2015) and is usually employed in an alternating miscible scheme
to recover oil. The only limitation being the precipitation of asphaltenes because
of CO 2 . They reported that the addition of metal oxide nanoparticles in tandem
with CO 2 injection gave a significant reduction in IFT. Even at higher asphaltene
contents, the reduction of IFT was appreciable. Figure 14 depicts the IFT reduction
with increasing asphaltene content in the presence of nanoparticles with different oil
samples (various API ranging from 16 to 26) obtained from various oil reservoirs in
Iran (Kazemzadeh et al. 2018). Figure 14b depicts that nickel oxide particles exhibit
a steady decrease in IFT as the asphaltene content increase. The charge distribution
of nickel oxide is effective in attracting asphaltenes away from the interface, thereby
reducing IFT. The deposition of asphaltenes on the surface of metal particles allows
more room for IFT reduction which in turn allows more CO 2 to get miscible with
the oil hence improving the sweep of oil.
Another strategy to use CO 2 is in the form of foam. The foam helps in increasing
the sweep and reduce mobility ratio. Foam also acts as a gas blocking agent which
further helps in the recovery of oil. Foam injection coupled with other EOR techniques can give very effective results in mobilising oil. Consequently, to improve
the efficiency of CO 2 foams, nanoparticles can be used as stabilizers to maintain
the foam structure inside the reservoirs. The stability of foams can be improved
to achieve better effects in the distance up to which the foams can propagate in the
reservoir. The hydrophilic/hydrophobic nature of nanoparticles helps in the stabilization of CO 2 foam. Occupancy of nanoparticles at the CO 2 interface provide thermal
stability to the foam at reservoir temperatures (Espinosa et al. 2010). Nanoparticlestabilized foams can provide a better sweep at a pore scale-level, which can result
in the increased overall recovery of oil (Nguyen et al. 2014). The use of nanofluids
in an alternating slug injection pattern coupled with CO 2 also results in inhibition
of asphaltenes. Lu et al. (2016) observed that asphaltene precipitation can be inhibited by asphaltene adsorption on Al 2 O 3 nanofluids. Using the nanofluids slug in
R. M. Jadhav and J. S. Sangwai
the best ways to obtain high recovery of heavy oil. However, there are other methods
that involve the use of injecting miscible gases and uses of solvents to treat heavy oil
have also seen a rise in the production of heavy oil.
4.2.1 Nanoparticle Stabilized Miscible Flooding
Miscible flooding operations and their impact are entirely dependent on the changes
in interfacial tension of the oil, reservoir rocks and the miscibility of the gas with
oil. Miscible gases cause swelling of oil which helps the oil inside pores to flow
more easily and allow better recovery. The arrangement of particles at the interface
controls the strength of the interfacial tension (IFT). IFT reduction is crucial for
processes such as miscible injections. The applicability of metal oxide nanoparticles
has pronounced effects on the IFT in the CO 2 injection process for heavy oil and
CO 2 upgrading systems. CO 2 injection is an effective mechanism to reduce IFT in
heavy oil systems. CO 2 dissolution also helps in lowering the viscosity of heavy
oils (Hu et al. 2015) and is usually employed in an alternating miscible scheme
to recover oil. The only limitation being the precipitation of asphaltenes because
of CO 2 . They reported that the addition of metal oxide nanoparticles in tandem
with CO 2 injection gave a significant reduction in IFT. Even at higher asphaltene
contents, the reduction of IFT was appreciable. Figure 14 depicts the IFT reduction
with increasing asphaltene content in the presence of nanoparticles with different oil
samples (various API ranging from 16 to 26) obtained from various oil reservoirs in
Iran (Kazemzadeh et al. 2018). Figure 14b depicts that nickel oxide particles exhibit
a steady decrease in IFT as the asphaltene content increase. The charge distribution
of nickel oxide is effective in attracting asphaltenes away from the interface, thereby
reducing IFT. The deposition of asphaltenes on the surface of metal particles allows
more room for IFT reduction which in turn allows more CO 2 to get miscible with
the oil hence improving the sweep of oil.
Another strategy to use CO 2 is in the form of foam. The foam helps in increasing
the sweep and reduce mobility ratio. Foam also acts as a gas blocking agent which
further helps in the recovery of oil. Foam injection coupled with other EOR techniques can give very effective results in mobilising oil. Consequently, to improve
the efficiency of CO 2 foams, nanoparticles can be used as stabilizers to maintain
the foam structure inside the reservoirs. The stability of foams can be improved
to achieve better effects in the distance up to which the foams can propagate in the
reservoir. The hydrophilic/hydrophobic nature of nanoparticles helps in the stabilization of CO 2 foam. Occupancy of nanoparticles at the CO 2 interface provide thermal
stability to the foam at reservoir temperatures (Espinosa et al. 2010). Nanoparticlestabilized foams can provide a better sweep at a pore scale-level, which can result
in the increased overall recovery of oil (Nguyen et al. 2014). The use of nanofluids
in an alternating slug injection pattern coupled with CO 2 also results in inhibition
of asphaltenes. Lu et al. (2016) observed that asphaltene precipitation can be inhibited by asphaltene adsorption on Al 2 O 3 nanofluids. Using the nanofluids slug in