Iranian Journal of Chemical Engineering (IJChE)

Abstract Conducting enhanced oil recovery (EOR) operations remains a critical challenge in the petroleum industry, necessitating innovative techniques to increase the efficiency of production from mature and low-permeability oil reservoirs. In this paper, a hybrid approach combining silica (SiO₂) and gamma-alumina (γ-Al₂O₃) nanoparticles with an anionic surfactant was experimentally investigated to assess their combined effects on key solution properties. Experiments were conducted under constant salinity and temperature to evaluate changes in wettability, interfacial tension (IFT), viscosity, density, and pH. A Central Composite Design (CCD) method was employed to optimize the concentration of nanoparticles and analyze their interactions with SDS. Results indicated that the formulated hybrid nanofluid substantially altered the wettability of the oil-wet glass surface, as indicated by the increase in the contact angle. The lowest IFT (1.485 mN/m) was achieved with one formulation, while the formulation selected for micromodel flooding (0.09 wt% SiO₂ + 0.05 wt% γ-Al₂O₃ + 0.1 wt% SDS) was chosen based on its overall performance across the measured properties, particularly wettability alteration and viscosity enhancement. The solutions also exhibited increases in viscosity and density by increasing the concentration of nanoparticles, which may influence fluid mobility and transport behavior. Oil recovery experiments in a quasi two-dimensional glass micromodel confirmed the effectiveness of the selected formulation, achieving an oil recovery of 60.6% of the original oil in place (OOIP) under the investigated conditions, compared with 13% for brine. These findings suggest that the hybrid nanoparticle–surfactant system may improve oil displacement under the investigated laboratory conditions.

Abstract "> Sodium montmorillonite (Na-MMT) was organically modified using 11- aminoundecanoic acid (AUA) and methacryloxyethyltrimethylammonium chloride (MAETAC) via cation exchange reaction. The effect of the modifier type and concentration on the structure and surface properties of the organically modified montmorillonites (OMMTs) was investigated. According to the results, the basal spacing of organoclays was enlarged considerably with increasing the AUA concentration, while increasing the MAETAC concentration had no significant influence on OMMT’s gallery height. On the other hand, contact angle measurements revealed that increasing the modifiers concentration would increase the hydrophobicity of pristine montmorillonite. The FTIR spectra showed that the OMMTs interlayer environment changed from liquid-like to solid-like as the modifier concentration increased. A mean-field lattice-based model was applied to various polymer/OMMT systems to predict the affinity between the prepared OMMTs and some polymers with different hydrophobicity. The model results showed that high polar and hydrophilic polymers, such as poly(ethylene oxide), exhibit more negative free energy change and stronger interaction with the OMMTs and, consequently, higher potential for preparation of composites with desirable nanostructure and mechanical properties.

Abstract Contrary to sandstone reservoirs, carbonate reservoirs have an oil-wetting nature. Water flooding of these fractured reservoirs with low permeability matrix blocks is not recommended unless a wettability alteration process is possible. Imbibition is an oil recovery mechanism for these types of reservoirs, if the rock matrix is water wet and there is enough water in fractures in contact with the matrix. Heavy matrix oil, high interfacial tension (IFT), oil-wet matrix sample, and limited contact area of matrix with water in fractures, requires additional effort to enhance the oil recovery by capillary imbibition. Surfactants can be injected into naturally fractured reservoirs to improve the capillary imbibition recovery performance. A well-known surfactant is Hexadecyl Trimethyl Ammonium Bromide (C 16TAB), which is an appropriate type of surfactant for these kinds of reservoirs. However, due to its high cost, it is rarely used in the real case
studies. In the present paper a simple and inexpensive method has been proposed for synthesizing this surfactant. Surfactant at different concentrations have been dissolved in high salinity brine, and the interfacial tension (IFT) between the aqueous solution and the oil has been measured by pendent drop method. In addition, the contact angle between the oil and the aqueous solution is measured by sessile drop method, and during the experiment, photos were taken every two seconds in order to analyse the IFT and the contact angle obtained. It has been found that reduction of IFT continues up to critical micelle concentration of the surfactant. Furthermore, a correlation has been obtained to predict the IFT between the oil and the high salinity aqueous solution containing different surfactant concentrations. Finally, the best surfactant concentration is obtained for reservoir case studies.