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The nanotechnology has been applied recently to increase the efficiency of enhanced oil recovery methods. The main objective of this study is to evaluate the effect of SiO 2 nanoparticle functionalization with different loadings of sodium oleate surfactant for polymer flooding processes. The sodium oleate surfactant was synthesized using oleic acid and NaCl. The SiO 2 nanoparticles were functionalized by physical adsorption using different surfactant loadings of 2.45, 4.08, and 8.31 wt % and were characterized by thermogravimetric analyses, Fourier-transform infrared spectroscopy, dynamic light scattering, and zeta potential. Adsorption and desorption experiments of partially hydrolyzed polyacrylamide (HPAM) polymer solutions over the unmodified and surface-modified nanoparticles were performed, with higher adsorption capacity as the surfactant loading increases. The adsorption isotherms have a type III behavior, and polymer desorption from the nanoparticle surface was considered null. The effect of nanoparticles in the polymer solutions was evaluated through rheological measurements, interfacial tension (IFT) tests, contact angle measurements, capillary number, and displacement tests in a micromodel. The surface-modified SiO 2 nanoparticles showed a slight effect on the viscosity of the polymer solution and high influence on the IFT reduction and wettability alteration of the porous medium leading to an increase of the capillary number. Displacement tests showed that the oil recovery could increase up to 23 and 77% regarding polymer flooding and water flooding, respectively, by including the surface-functionalized materials.

In this paper, the formation of water in oil (W/O) model solution emulsions using untreated and oxidized asphaltenes as emulsifiers was evaluated. Emulsions were formed with deionized water and toluene at different water/toluene ratios (1:4, 1:1, and 4:1) and concentrations of asphaltenes of 100, 500, and 1000 mg/L. Asphaltenes were oxidized at two different temperatures of 373 and 473 K for various exposure times. Untreated and oxidized asphaltenes were characterized by thermogravimetric analyses, C, H, N, S and O elemental analyses, solvency tests in toluene, and qualitative structural indexes from Fourier-transform infrared spectroscopy. The emulsions were evaluated for stability, the percentage of oil in water (O/W) and W/O phases, interfacial tension (IFT), and mean droplet diameter. The asphaltenes solubility decreased up to 93% as the temperature of oxidation and the exposure time increased. The amount of W/O emulsion increases when asphaltene concentration, exposure time, and oxidation temperature increase. With oxidized asphaltenes at 373 and 473 K, the formation of W/O emulsions increased by approximately 30% and 70% for a fixed asphaltene concentration, respectively. IFT revealed that after oxidation, no carboxylic acids were formed. A hypothetical oxidation reaction of asphaltenes to ketones and sulphoxide, and nitrogen and alkyl chain removal is proposed.

Viscosity losses and high degradation factors have a drastic impact over hydrolyzed polyacrylamides (HPAM) currently injected, impacting the oil recovery negatively. Previous studies have demonstrated that biopolymers are promising candidates in EOR applications due to high thermochemical stability in harsh environments. However, the dynamic behavior of a biopolymer as scleroglucan through sandstone under specific conditions for a heavy oil field with low salinity and high temperature has not yet been reported. This work presents the rock–fluid evaluation of the scleroglucan (SG at 935 mgL−1) and sulfonated polyacrylamide (ATBS at 2500 mgL−1) to enhance oil recovery in high-temperature for heavy oils (212 °F and total dissolved solid of 3800 mgL−1) in synthetic (0.5 Darcy) and representative rock samples (from 2 to 5 Darcy) for a study case of a Colombian heavy oilfield. Dynamic evaluation at reservoir conditions presents a scenario with stable injectivity after 53.6 PV with a minimal pressure differential (less than 20 psi), inaccessible porous volume (IPV) of 18%, dynamic adsorption of 49 µg/g, and resistance and residual resistance factors of 6.17 and 2.84, respectively. In addition, higher oil displacement efficiency (up to 10%) was obtained with lower concentration (2.7 times) compared to a sulfonated polyacrylamide polymer.

In this study, the surface of silica nanoparticles (NPs) synthesized using the Stober method was modified with 3-aminopropyltriethoxysilane and hydrolyzed polyacrylamide (HPAM). The surface modification of the silica NPs was confirmed by Fourier transform infrared spectroscopy, field emission gun scanning electron microscopy, and thermogravimetric analysis. The characteristics of the nanopolymer sol were evaluated using rheology, viscosity retention ratio, interfacial tension, and contact angle measurements. The core flooding experiments were performed at 56 °C using Berea core plugs with Klinkenberg permeabilities of 450 and 478 mD and a porosity of ∼21%. The nanopolymer sol was prepared in injection brine (0.24 wt % TDS) with 550 ppm of the nanohybrid, while the polymer solution was prepared with 750 ppm of HPAM. The displaced fluid was dead oil with a viscosity of 60 cP (@56 °C and 7.3 s −1 ). The results show that the nanopolymer sol reduces the capillary forces and increases the viscous forces compared to the HPAM solution. These improved properties of the nanopolymer sol were suitable for increasing the cumulative oil recovery in 2.2% OOIP in comparison with the HPAM solution at a lower concentration.