Interaction of Nanoparticles with Reservoir Fluids and Rocks …
313
3.1.3 Effect of Titanium Dioxide Nanoparticles
Titanium dioxide (TiO 2 ) nanoparticles are crystalline in structure and have wide
applications in different fields. The application of TiO 2 in EOR is found to be negligible because of its cost and comparatively paid less attention by the researchers.
Ehtesabi et al. (2014) have revealed that there is no significant change in reduction
of IFT between injected fluid and oil in the presence of Titanium dioxide (TiO 2 )
nanoparticles (15 nm). However, it has influenced surface modification of rocks
due to its deposition over the rock surfaces. The minimum IFT reduction generally
achieved at lowest pH, however, it was not observed in case of the TiO 2 nanoparticles. It was reported that enhanced oil recovery is due to change in wettability of
surface rather than IFT. Hendraningrat et al. (2013) state that the stability of nanofluid
is challenging factors, because NPs have tendency to agglomerate due to forces of
different natures. Therefore, it is essential to choose proper dispersive medium for
preparation of stable nanofluid emulsion. However stability of TiO 2 nanoparticles
(106 nm) was noticed to be possessed good stability at higher temperature of 50 °C.
Moreover, a considerable reduction in oil viscosity was observed after TiO 2 nanofluids flooding at 50 and 60 °C, whereas no significant reduction in IFT was observed
(Ali et al. 2014).
3.2 Wettability
Wettability is the tendency of one fluid to spread on or adhere to on a solid surface
in the presence or absence of other immiscible fluids. Wettability can be understood
as the interaction between the fluid and solid phases. In a reservoir, the liquid phase
can be water or oil, and the solid phase is the rock of the reservoir pores in which
contain crude oil. It is one of the most critical variables in enhanced oil recovery
and also affects few other reservoir parameters such as capillary pressure, relative
permeability, and sweeping efficiency of injected fluids (Almahfood and Bai 2018).
The reservoir by wettability can be divided into three types: (i) oil-wet reservoir,
(ii) mixed-wet reservoir, and (iii) water-wet reservoir. Production of oil from the
oil-wet reservoir is least as compared to other two due to weak sweeping efficiency;
however, the recovery of oil from water-wet reservoir is more than that of the mixedwet reservoir. Hence, modification of wettability is essential for the improved oil
recovery process. Wettability evaluation is carried out by contact angle measurement
method. Theoretically, the contact angle is found out by Young’s equation, i.e.,
Y lv Cosθ Y = Y sv − Y sl
Y lv , Y sv , and Y sl are the interfacial tension of liquid–vapor, solid–vapor, and solid–
liquid phases. θ Y is Young’s contact angle. Similarly, Telescope-Goniometer is used
to determine the contact angle of various liquid on the polish surface experimentally.
A pictorial representation of wetting nature of the surface is given in Fig. 9.
313
3.1.3 Effect of Titanium Dioxide Nanoparticles
Titanium dioxide (TiO 2 ) nanoparticles are crystalline in structure and have wide
applications in different fields. The application of TiO 2 in EOR is found to be negligible because of its cost and comparatively paid less attention by the researchers.
Ehtesabi et al. (2014) have revealed that there is no significant change in reduction
of IFT between injected fluid and oil in the presence of Titanium dioxide (TiO 2 )
nanoparticles (15 nm). However, it has influenced surface modification of rocks
due to its deposition over the rock surfaces. The minimum IFT reduction generally
achieved at lowest pH, however, it was not observed in case of the TiO 2 nanoparticles. It was reported that enhanced oil recovery is due to change in wettability of
surface rather than IFT. Hendraningrat et al. (2013) state that the stability of nanofluid
is challenging factors, because NPs have tendency to agglomerate due to forces of
different natures. Therefore, it is essential to choose proper dispersive medium for
preparation of stable nanofluid emulsion. However stability of TiO 2 nanoparticles
(106 nm) was noticed to be possessed good stability at higher temperature of 50 °C.
Moreover, a considerable reduction in oil viscosity was observed after TiO 2 nanofluids flooding at 50 and 60 °C, whereas no significant reduction in IFT was observed
(Ali et al. 2014).
3.2 Wettability
Wettability is the tendency of one fluid to spread on or adhere to on a solid surface
in the presence or absence of other immiscible fluids. Wettability can be understood
as the interaction between the fluid and solid phases. In a reservoir, the liquid phase
can be water or oil, and the solid phase is the rock of the reservoir pores in which
contain crude oil. It is one of the most critical variables in enhanced oil recovery
and also affects few other reservoir parameters such as capillary pressure, relative
permeability, and sweeping efficiency of injected fluids (Almahfood and Bai 2018).
The reservoir by wettability can be divided into three types: (i) oil-wet reservoir,
(ii) mixed-wet reservoir, and (iii) water-wet reservoir. Production of oil from the
oil-wet reservoir is least as compared to other two due to weak sweeping efficiency;
however, the recovery of oil from water-wet reservoir is more than that of the mixedwet reservoir. Hence, modification of wettability is essential for the improved oil
recovery process. Wettability evaluation is carried out by contact angle measurement
method. Theoretically, the contact angle is found out by Young’s equation, i.e.,
Y lv Cosθ Y = Y sv − Y sl
Y lv , Y sv , and Y sl are the interfacial tension of liquid–vapor, solid–vapor, and solid–
liquid phases. θ Y is Young’s contact angle. Similarly, Telescope-Goniometer is used
to determine the contact angle of various liquid on the polish surface experimentally.
A pictorial representation of wetting nature of the surface is given in Fig. 9.