Experimental Investigation of Silica-Based Nanofluid Enhanced Oil Recovery: The Effect of Wettability Alteration

Abstract

Enhanced oil recovery (EOR) using nanofluids has been proposed in recent years, but the mechanism of oil recovery enhancement through nanofluid injection still needs further study. In this study, the pore-scale performance and mechanism of nanofluid EOR were investigated based on a micromodel experiment. The micromodel sample was designed to compare the silica-based homogeneous water-wet sandstone reservoirs. The behavior of 0.1% wt water-base silica nanofluid-displacing oil (dodecane) was compared to the deionized (DI) water-displacing case. Residual oil saturation gradually decreases from 50% to 43% as the DI water injection flow rate increases from 0.5 to 5.0 μL/min. In the nanofluid-injection case, residual oil saturation decreases from 24% to 20% as the flow rate varies in the same range. About 25% saturation of incremental oil recovery is obtained by nanofluid injection compared to DI water injection. This implies significant improvement in oil recovery performance from nanofluid injection. Through investigation of detailed pore-scale fluid distribution, the wettability alteration of the oil-bearing pore wall from a strongly water-wet condition to the neutrally wet condition is observed in the presence of nanoparticles. The wettability alteration behavior in a natural sandstone sample was investigated via a spontaneous imbibition test. The imbibition rate slows down significantly in the presence of nanoparticles indicating that the wettability alteration mechanism observed in the micromodel experiment is also valid in the case of natural water-wet sandstones and consequently can enhance the oil recovery. The analysis based on Wenzel’s model indicates that the nanoparticle adsorption-induced nonuniform pore wall roughness change is the possible mechanism for wettability alteration.

The Effect of Wettability Heterogeneity on Relative Permeability of Two‐Phase Flow in Porous Media: A Lattice Boltzmann Study

“…The dynamic viscosities of water and dodecane are 0.894 and 1.364 Pa s, respectively. And the interfacial tension between water and dodecane is 39.16 mN/m (Li et al, ). To change the physical unit into lattice unit, three reference quantities need to be selected (Liu et al, ): the length scale L 0 , the time scale T 0 , and the mass scale M 0 .…”

Pore-scale visualization on a depressurization-induced CO2 exsolution

“…3. The detailed description of the micromodel pattern and fabrication process can be found in our previous study [37]. The micromodel was visualized using an inverted microscope (Ti-E Nikon series) with a fluorescence module.…”

Polymer-functionalized silica nanoparticles for improving water flood sweep efficiency in Berea sandstones

“…This, in turn, makes it difficult to adequately grasp the oil recovery mechanisms of silica nanoparticles. Aside from i) IFT reduction and wettability alteration, which are the two most suggested mechanisms [11,15,16,18], NPs improve oil recovery by ii) structural disjoining pressure [26], iii) formation of emulsions [19][20][21], and iv) log-jamming effect [5-7, 13, 22-24]. In some circumstances, more than one mechanism is associated with oil recovery.…”