Synergy Between CTAB, AOT, TiO2 And CuO NPs for Surface Properties Modifications; Effects  of Acidic Crude Oil and Syntehtic Mixed Resinous and Asphaltenic Oil and Saline Water

It is well established that the presence of chemicals and nanoparticles (NPs) in aqueous solutions has a significant impact on surface properties, particularly in the context of interactions with oil components. The asphaltene and resin fractions of crude oil, regardless of the oil type, greatly influence surface phenomena. In light of these facts, the current investigation aims to assess the impacts of two surfactants—dioctyl sulfosuccinate sodium (AOT) and cetrimonium bromide (CTAB)— (with concentration of 0-2000 ppm) along with titanium oxide (TiO ₂ ) (with concentration of 0-500 ppm) and copper oxide (CuO) nanoparticles (NPs) (with concentration of 0-250 ppm) on interfacial tension (IFT) reduction and wettability alteration, using contact angle (CA) analysis for two types of acidic crude oil (ACO) and synthetic mixed resinous and asphaltenic oil (SMRAO). The measurements revealed that AOT is more efficient for IFT reduction, especially when using 50% diluted Persian Gulf water (DPGW). It was found that replacing distilled water (DW) with DPGW has a significant effect on IFT reduction by reducing the IFT values from 33.5 and 26.2 mN/m for ACO and SMRAO to 23.6 and 19.9 mN/m for ACO and SMRAO in contact with DPGW, respectively, likely due to the presence of sulfate ions and other ions that can function as “smart water.” In essence, the results indicated that the use of DPGW enhances the surface activity of the aqueous solution, and the addition of surfactants maximizes this effect by reducing the IFT value to minimum values of 0.95 and 0.69 mN/m for AOT solutions with concentration of 2000 ppm dissolved in DPGW in contact with ACO and SMRAO, respectively. In the second stage, the effects of surfactants on wettability alteration were investigated through contact angle measurements. These tests demonstrated a substantial impact of DPGW and the dissolved surfactants on wettability alteration. Specifically, the individual effect of DPGW led to a reduction in CA from 141.2° and 152.9° for ACO and SMRAO with DW, down to 98.5° and 91.1°, respectively which was toward neutral or mixed wettability conditions. Further measurements indicated that the presence of surfactants can enhance wettability alteration capabilities, with AOT showing a greater effect, resulting in contact angles of 40.1° and 39.7° for ACO and SMRAO, respectively. Notably, both IFT and CA measurements indicated that systems dealing with SMRAO experienced better IFT reduction and more effective wettability alteration, attributed to the surface-active nature of the resin and asphaltene, which act as additional surfactants. Moreover, the acidic nature of these fractions may provide additional opportunities for in-situ soap production and saponification processes that function as surfactants. The presence of NPs, specifically TiO ₂ and CuO at concentrations of 0-500 ppm and 0-250 ppm, respectively, showed an improved potential for wettability alteration, trending toward a more water-wet condition, with TiO2 (500 ppm) in AOT (1000 ppm) solutions demonstrating superior results with CA values of 27.7 ^o and 23.3 ^o for ACO and SMRAO, respectively. Besides, the synergistic impact of these two NPs were examined on the wettability alteration using a solution activated with 1000 ppm of CTAB and AOT with concomitant presence of 100 ppm of TiO ₂ and 100 ppm of CuO on the CA values. The measurements revealed a significant reduction in CA with lower amount of NPs demonstrating an excellent synergistic effect of chemicals with each other with minimum CA values of 31.2 ^o and 26.6 ^o for ACO and SMRAO, respectively, for AOT solution and those NPs. Finally, several optimum chemical formulations along with the solutions prepared with hybrid NPs were used to perform core flooding experiments revealed the possibility of producing 12.8 % based on original oil in place (OOIP) and 16.6% based on OOIP if 30 days of soaking are replaced with quick flooding, since wettability alteration can reach its ultimate impact during 30 days of soaking.