Interactions between Ca(OH)2, imidazolium ionic liquid, and titanium oxide nanoparticles using resinous and asphaltenic synthetic oils under high-salinity conditions
Authors: Mehdipour Reza , Hosseini Seyednooroldin 
Published: September 2023

Using chemical methods in enhanced oil recovery (EOR) processes is limited since the mechanisms, interactions, and synergisms combined with heterogeneities and network complexities besides the incompatibilities of different chemicals are encountered in the chemical EOR methods with some uncertainties. Also, since using only one chemical, namely surfactant, alkali, and polymer, has a bounded effect on the oil recovery, it is highly required to combine different chemical-based methods to achieve ultimate oil recovery. Unfortunately, since most of the developed surfactants cannot tolerate harsh salinity and temperature conditions, it is highly essential to tailor efficient and stable surfactants for those conditions. Moreover, since crude oil is comprised of thousands of different compounds which are different from one crude oil to the other crude oil, using a specific fraction of oils such as asphaltene and resin has high potential to provide more applicable and generalized results. In the light of this fact, the current investigation is designed and performed for the first time to combine different methods for better synergies for higher oil production using a new class of surfactant (1-tetradecyl-3-methylimidazolium chloride ([C14mim][Cl])), titanium oxide nanoparticles (TiO2–NPs), and alkali (Ca(OH)2) concomitant with NaCl and KCl with concentrations of 50,000–200,000 ppm. The point is that, instead of using crude oil with many compounds, only resin and asphaltene fractions extracted from a heavy acidic crude oil are used as the model oil (8 wt%). The measurements revealed the reducing effect of asphaltene and resin fraction on the interfacial tension (IFT), while the presence of NaCl and KCl makes this trend more complicated. The measurements also revealed an undeniable effect of Ca(OH)2 on the IFT reduction, especially in the presence of NaCl (concentration of 200,000 ppm), no matter using resinous or ASO. Moreover, the IFT measurements revealed the significant effect of used 1-tetradecyl-3-methyl imidazolium chloride ([C14mim][Cl]) on the IFT reduction with minimum values of 0.12 mN/m and 0.32 mN/m for 200,000 ppm of NaCl + Ca(OH)2 of 1500 ppm and 200,000 ppm KCl and Ca(OH)2 of 1000 ppm, respectively. Besides, the measurement revealed that the addition of TiO2 nanoparticles (TiO2–NPs) in the range of 0–100 ppm reduces the IFT to 0.069 mN/m and 0.08 mN/m, respectively. On the other side, the contact angle (CA) measurements and Amott wettability index calculation revealed the better impact of NaCl-based chemical formulation along with the used TiO2–NPs on the wettability alteration toward strongly water-wet conditions than the KCl-based chemical formulations. In the last stage, the performed core flooding experiments using forced imbibition and spontaneous imbibition concepts reveal that the obtained chemical formulations are capable to change the wettability of the rocks toward mixed conditions, while the forced imbibition tests (conventional core flooding experiments) revealed excellent effect of IFT reduction for more oil production with a maximum value of 15.3% based on the original oil in place (OOIP).