Investigating the Synergistic/Antagonistic Effects of Mixing SiO<sub>2</sub> Nanoparticles and Ionic Liquid, Nonionic Emulsifier, and Gemini Surfactants on the Main Mechanisms of Crude Oil Production
Reyhaneh Fattahi, Mostafa Lashkarbolooki, Reza Abedini, Habibollah Younesi
Abstract
In this study, the synergistic/antagonistic effects between hydrophilic SiO 2 nanoparticles, synthesized from rice husk ash, and various surfactant types including a cationic imidazolium-based ionic liquid ([C 12 mim][Cl]), a twin-branched tailed anionic gemini surfactant (AOT), and a nonionic emulsifier (Tween 80) on the reduction of interfacial tension (IFT), the change of wettability of dolomite rock (analyzed using energy-dispersive X-ray (EDX) and field-emission scanning electron microscopy (FESEM)), the formation of the microemulsion, spreading coefficient ( S C ), and capillary number during injection of mixing of SiO 2 nanoparticles and surfactants in the fracture and nonfracture oil reservoirs were investigated. The results showed that the addition of 100 ppm of SiO 2 nanoparticles to seawater changed the wettability of dolomite rock from the neutral state to strongly water-wet (contact angle was decreased from 89 to 20°), but it did not have much effect on the IFT value (IFT was changed from 8.7 to 7.8 mN/m). Even though the IFT values of surfactant solutions were almost unaffected by the addition of SiO 2 nanoparticles, an antagonistic effect was observed for wettability; by adding AOT, [C 12 mim][Cl], and Tween 80 surfactants to the aqueous solution containing 100 ppm of SiO 2 nanoparticles, the contact angle increased from 20 to 140, 140, and 127°, respectively. Furthermore, from comparison to the literature data, it is found that the best spreading coefficient and capillary number can be achieved for AOT and [C 12 mim][Cl] in the absence of SiO 2, respectively. The AOT surfactant was proposed as an appropriate agent, especially in the fractured reservoir, due to its capability to reduce IFT and change the wettability of carbonate rock to the water-wet state (modifying the imbibition mechanism), thus resulting in a spreading coefficient of near zero value ( S C = −0.04), and provide the most desirable microemulsion condition (formation of Type III microemulsion).