In the current study, the effect of CuO nanoparticles (CuO-NPs) at the presence of dodecyl-3-methylimidazolium chloride ([C₁₂mim][Cl]) is investigated on the interfacial tension (IFT) reduction, wettability alteration, and even tertiary oil recovery. Since the prepared solutions with CuO-NPs are completely dark and it is impossible to measure the IFT of these solutions in the presence of crude oil using the pendant drop method (since one of the phases must be transparent for IFT measurement using the pendant drop method), n-heptane (representative of saturates) and toluene (representative of aromatics) are used only for IFT measurement of solutions prepared by CuO-NPs, while rest of the experiments are performed using crude oil. The obtained results reveal that CuO-NPs are not stable in the aqueous solution in the absence of surfactant which means fast precipitation of CuO-NPs and a high risk of pore plugging. In this way, the stability of CuO-NPs is investigated at the presence of dodecyl-3-methyl imidazolium chloride ([C12mim][Cl]) as an effective surfactant for stabilizing the CuO-NPs in the aqueous solution (more than 1 month without precipitation using 1000 ppm of IL). Further measurements reveal that although the presence of IL in the aqueous solution can reduce the IFT of oil/aqueous solution system, especially for the aqueous solutions prepared by formation brine (0.65 mN.m⁻¹), the presence of CuO-NPs has no considerable effect on the IFT. On the other hand, not only the contact angle (CA) measurements reveal the considerable effect of IL on the wettability alteration toward water-wet condition (68.3° for IL concentration of 1000 ppm) but also the addition of CuO-NPs can significantly boost the wettability alteration toward strongly water-wet condition (23.4° for the concentration of 1000 ppm of CuO-NPs). Finally, several core flooding experiments are performed using different combinations of chemicals to find the effect of these chemicals on the tertiary oil recovery factor. The results reveal that the presence of CuO-NPs can enhance the oil recovery of injected chemical slug (aqueous solution prepared by dissolution of IL with an oil recovery factor of 10.1% based on Original oil in place (OOIP)) to 13.8, %, 16.9%, and 21.2% based on OOIP if 500, 1000, 2000 ppm of CuO-NPs existed in the solution concomitant with 1000 ppm of [C₁₂mim][Cl].

Using nanoparticles (NPs) in different industries such as enhanced oil recovery processes increased during the past decade due to its significant effects on the wettability alteration and IFT reduction to some extent. On the other side, ionic liquids (ILs) are proposed a new class of solvents that introduce considerable advantages in different areas of sciences. In this way, a hybrid method based on the NPs and ILs is proposed in the current investigation. So, silicon dioxide (SiO₂₎ as one of the most effective NPs on the wettability alteration and 1-dodecyl-3-methyl imidazolium chloride ([C₁₂mim][Cl]) as a new class of surfactants are used to find their effects on the interfacial tension (IFT) reduction and wettability alteration at the presence of asphaltenic synthetic oil for the first time. In this way, the stability of SiO₂-NPs at the presence of and absence of IL is examined which revealed stability of SiO₂-NPs for more than one month at the presence of IL while fast precipitation was observed if no IL existed in the solution. After that, the effect of IL and SiO₂-NPs on the IFT reduction and wettability alteration is investigated by changing the concentration of these chemicals between 0 and 2000 ppm and ranging the asphaltene content between 2 and 10%wt. The results revealed that for all of the examined concentrations of IL and asphaltene fraction, reduction in IFT is inevitable as the concentration increases. Besides, the results demonstrate that there is a threshold value for asphaltene content (6%wt) in which for the values below or higher than this threshold, the effect of IL on the IFT reduction reduces leading to the vanishing of a sharp reduction in IFT and determining a distinguished critical micelle concentration (CMC). According to findings, for asphaltenic synthetic oil (ASO) with 6%wt asphaltene content CMC value of 250 ppm is obvious while for the other ASO, no obvious and distinguished CMC values exist. Moreover, the results reveal that the IFT reduces to the value of 0.48 mN/m as the IL concentration increases to 2000 ppm while the asphaltene content is kept constant at 6%wt. Further IFT measurements demonstrate the negligible effect of SiO₂-NPs on the IFT reduction while the concomitant existence of SiO₂-NPs and IL with the concentration of 1000 ppm moves the wettability of the rock surface toward strongly water-wet with contact angle (CA) of 33.1°. The worth mentioning point is that the entire amount of reduction in the CA from 156.3° (initial condition) to 33.1° at the presence of hybrid solution is not completely due to the presence of SiO₂-NPs and it is the cumulative effect of IL and SiO₂-NPs presence. Finally, several core flooding experiments are performed using different chemical formulations which reveal that using a hybrid solution of SiO₂-NPs + IL with a concentration of 1000 ppm for each chemical increases the tertiary oil recovery to 15.2%wt based on OOIP for the ASO/formation brine with asphaltene content of 10%wt.

The effects of the main components of crude oil, especially resin and asphaltene fractions, are essential concerns for efficient enhanced oil recovery (EOR) processes, especially during chemical injection processes. This importance comes from the nature of these two fractions which can act as surface active agents with undeniable effects on the used chemical for interfacial tension (IFT) reduction and wettability alteration. In this way, the effect of silicon oxide nanoparticles (SiO₂-NPs) concomitant with two ionic liquids (ILs), namely 1-dodecyl-3-methyl imidazolium chloride ([C₁₂mim][Cl]) and 1-octadecyl-3-methyl imidazolium chloride ([C₁₈mim][Cl]), is investigated on the wettability alteration and IFT reduction using synthetic oils prepared by dissolving the extracted resin and asphaltene fractions with a concentration of 1–5 wt%. The measurements reveal that the effect of resin fraction is less than the asphaltene fraction for IFT reduction and wettability alteration. The sole presence of resin fraction reduces the IFT from 35.3 to 28.3 mN/m as the concentration is increased from 1 to 5 wt%, while a similar increase in the asphaltene fraction concentration reduces the IFT from 35.5 to 19.1 mN/m. Besides, the results reveal that the presence of [C₁₂mim][Cl] in the range of 0–1000 ppm leads to a reduction in IFT from its maximum value of 35.3 to 0.81 mN/m, while in the case of [C₁₈mim][Cl] with similar concentration variation, IFT is reduced from 35.3 to 0.7 which means the better effect of IL with longer chain length on the IFT reduction. Further analysis revealed that the effect of asphaltene fraction on the IFT is higher than resin fraction since the minimum IFT value was observed for [C₁₈mim][Cl] with the value of 0.58 mN/m, while the contact angle (CA) values revealed revers effect for asphaltene fraction compared with the resin fraction. In general, regardless of the used IL, it seems that ILs leading to better wettability conditions which are crucial for EOR purposes and even better IFT values that can mobilize the trapped oil toward production points. Besides, further measurements revealed a positive effect of SiO₂-NPs concomitant with the ILs to move the wettability toward the strongly water-wet condition with CA values of 29.2° and 28.3° for SiO₂-NPs concentration of 1000 ppm and 1000 ppm of concentration for [C₁₂mim][Cl] and [C₁₈mim][Cl], respectively, for resinous synthetic oil (RSO) (5 wt%) while no meaningful effect regarding the SiO₂-NPs presence at the different concentrations (100–2000 ppm) is found on the IFT reduction. A similar trend is observed for asphaltenic synthetic oil (5 wt%)/aqueous solution (SiO₂-NPs with a concentration of 1000 ppm + ILs with a concentration of 1000 ppm) which reduces the CA to 26.3° and 37.8° for [C₁₂mim][Cl] and [C₁₈mim][Cl]), respectively.

The current study is designed and performed to examine the impact of a combinative method including the new class of surfactants from the ionic liquids (ILs) family (imidazolium type) and nanoparticles (NPs) namely silicon dioxide nanoparticles (SiO₂-NPs). Besides, the effect of pH concomitant with the other parameters was examined since pH is an essential operating parameter especially if researchers dealing with a non-neutral type of crude oil. Unfortunately, although using chemicals is highly effective, there are limited investigations dealing with a new class of surfactants, NPs, and operating conditions such as pH. In other words, although there are several investigations dealing with alkaline, polymers, and surfactants, a few studies were performed to find the interactions between the new class of surfactants such as ILs, NPs (no matter metallic-based or nonmetallic-based type) and pH which can directly manipulate the in-situ surfactant formation which acts similarly to alkaline injection. In this way, two different surfactants namely 1-dodecyl-3-methyl imidazolium chloride ([C₁₂mim][Cl]), and 1-octadecyl-3-methyl imidazolium chloride ([C₁₈mim][Cl]) and SiO₂-NPs with concentrations of 0–2000 ppm and 0–1000 ppm are used for interfacial tension (IFT) and wettability alteration investigations using heavy acidic crude oil. The measured IFT values revealed that increasing the surfactant concentration to 2000 ppm can reduce the IFT to the minimum value of 0.94 and 0.88 mN/m for [C₁₂mim][C] and [C₁₈mim][Cl], respectively. Besides, the measurements revealed that it is possible to reach the water-wet condition with contact angles of 81.3° and 74.5° for [C₁₂mim][Cl] and [C₁₈mim][Cl], respectively. Moreover, the measurements revealed that increasing the pH from 3 to 11 has a considerable effect on the IFT reduction and wettability alteration because of in-situ surfactant formation (reaction between the OH⁻ and the functional group of the crude oil) which can act as a solution including alkaline in it. Finally, the IFT and contact angle were measured using 1000 and 500 ppm of [C₁₂mim][Cl] and [C₁₈mim][Cl] while the pH and SiO₂-NPs concentrations ranged between 3–11 and 0–1000 ppm, respectively. The measurements revealed the significant impact of SiO₂-NPs for reducing the IFT and changing the wetness of the rock surface with a minimum IFT value of 0.35 mN/m and contact angle of 23.3° (strongly water-wet condition). Considering the obtained results, it can be concluded that the proposed combinative method is highly applicable for higher oil production using the lab-scale equipment. The point is that the further systematic investigations are required since using combinative methods for enhanced oil recovery (EOR) purposes are still in the preliminary stages of their appearance.

During the past years, the usage of new oil recovery methods known as enhanced oil recovery methods is increasing because of energy consumption rate enhancement and reservoir pressure depletion. Unfortunately, since most of the investigations were focused on crude oil, it is hard to find a generalized pattern of interfacial tension (IFT) and wettability change for different crude oils because of its complicated composition. So, it is necessary to examine the effect of specific fractions of crude oil especially resin and asphaltene fractions on the IFT and wettability alteration using systematic investigations. Although a limited number of investigations examined the interactions between these specific fractions and salts, there are no systematic reports respecting the possible interactions between asphaltene and resin fractions in the presence of alkaline and surfactant. So, in the first stage, the impact of dissolving asphaltene (0–9 wt%) in the toluene was investigated on the IFT reduction which revealed a decrease in IFT value from 34.8 to 23.3 mN/m as the asphaltene concentration was increased. Further experiments showed that the presence of MgCl₂ and NaCl with a maximum concentration of 5000 ppm led to a reduction in IFT to a minimum value of 18.3 and 17.3 mN/m for NaCl and MgCl₂, respectively, which means the higher impact of MgCl₂ on the IFT reduction. After that, the selected optimum concentrations of MgCl₂ and NaCl (5000 ppm) were used in the rest of the experiments in which the effect of resin fraction and other chemicals including sodium dodecyl benzenesulfonate (SDBS) and NaOH concentrations was examined on the IFT reduction and rock wettability. According to the obtained results, it was possible to reach the minimum IFT value of 0.08 mN/m, which is several orders lower than the original IFT value of the binary system without the chemicals using the optimum chemical formulation obtained by mixing proper concentrations of SDBS, NaOH, MgCl₂, and NaCl. Moreover, the obtained optimum formulations were used through core flooding experiments which revealed the possibility of increasing the oil recovery to a maximum value of 10.1% based on the original oil in place.