Estimation of the Capability of Surfactant in Reducing the Interfacial Tension in Surfactant/Alkali/Crude Oil Systems via Quantification
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The dynamic interfacial tension in surfactant/alkali/acidic oil systems was investigated in a mode of three arylalkyl surfactant flooding. The results indicate that there exists an optimum range of alkali concentrations when the minimum interfacial tension value is below 10−2 mN/m (the ultra-low interfacial tension value) at certain surfactant concentrations. The minimum interfacial tension presents a similar parabolic relationship with alkali concentrations and also a similar hyperbolic relationship with surfactant concentrations as well. Thus, a convexity can be built by the results of three variables, i.e., the minimum interfacial tension, surfactant concentration, and alkali concentration. The capability of synthesized arylalkyl surfactants in reducing the interfacial tension can be expressed by the values of the volumes formed by the three variables. The higher value indicates the stronger capability of the surfactant in reducing the interfacial tension. This method for the capability of surfactant being quantified would offer a new way to choose the surfactants in enhanced oil recovery.Keywords:
Tension (geology)
A series of highly pure surfactants was synthesized.Pure surfactant was added into the alkali solution in order to simplify the flooding system.The relationships of structure of surfactant and concentration of alkali with dynamic interfacial tension (IFT) were studied.There exhibited good interfacial behavior when the distribution coefficient of surfactant between two phases was suitable.
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Nanoparticles (NPs) and surfactants can spontaneously concentrate at the interface between two immiscible liquids, such as oil and water. Systems of high oil–water interfacial area, such as emulsions, are the basis of many industries and consumer products. Although NPs and surfactants are currently incorporated into many of these applications, their mutual interfacial behavior is not completely understood. Here we present molecular dynamics simulations of NPs and non-ionic surfactant in the vicinity of an oil–water interface. It was found that in low concentration the surfactants and NPs show cooperative behavior in lowering the oil–water interfacial tension, while at higher surfactant concentration this synergy is attenuated. It was also found that binding of surfactants to the NP surface decreases the surfactant efficiency in lowering the interfacial tension, while concurrently creating a barrier to NP aggregation.
Oil droplet
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Brine
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Tension (geology)
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Abstract Experimental studies were conducted to explore the fundamental mechanisms of alkali to lower the interfacial tension of oil/heavy alkylbenzene sulfonates (HABS) system. Sodium hydroxide was used as the strong alkali chemical to investigate the interfacial tension (IFT) of oil/HABS system. The influences of salt and alkali on the interfacial activity were studied by the measurement of interfacial tension and partition coefficient. Moreover, the alkali/surfactant solutions were measured by dynamic laser scattering. The results showed that compared with the salt, the function of alkali to lower the interfacial tension and improve partition coefficient is more significant. The micelles formed by surfactants could be disaggregated because of adding alkali, so the size of micelles decreases and the number of mono‐surfactants increases, then more surfactant molecules move to the interface of oil/surfactant system and the adsorption of surfactants at oil‐water interfaces increases, which can lead to the decrease of IFT.
Sodium hydroxide
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Chemical surfactant injection is one of the Enhanced Oil Recovery (EOR) technologies, revealing a large potential to recover the undisplaced oil into the porous media. Many techniques to improve this methodology have been proposed recently, such as the use of nanoparticles. However, very few studies have focused on the effect of the surface hydrophobicity of nanoparticles on the surfactant efficiency improvement. Furthermore, most studies focus on the use of formulations composed by a single molecule, but in common field applications, the use of surfactant mixtures is recommended since lower Interfacial Tensions (IFT) can be reached. This research work aims to study the use of two different hydrophobicity nanoparticles (Aerosil 308 and Aerosil R812S), to improve the efficiency of an anionic surfactant mix formulation (typically used for EOR processes) from oil/water interfacial reduction and adsorption inhibition. The main purpose is to analyze the resulting interactions between the nanoparticle and the surfactant molecules through IFT measurements and surfactant adsorption inhibition on a solid surface. All systems stability were determined using a Turbiscan, interfacial tensions were measured by a spinning drop tensiometer and, static and dynamic adsorption were calculated to determine the behavior of the main formulations. Results showed the surface nature of nanoparticles has an important effect on the oil–water interfacial tension evolution and on the surfactant adsorption inhibition. Both nanoparticles' types showed a good performance under specific conditions. However, hydrophilic nanoparticles exhibited a better performance than hydrophobics. The Interfacial performance displayed nonmonotonic trends, especially in adsorption assessments wherein static and dynamic experiments exhibited different behaviors for the same type and concentration of nanoparticle, displaying a different pattern from the literature.
Fumed silica
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Abstract Non-ionic alkyl polyglucoside (APG) surfactants have been considered as eco-friendly, nontoxic and biodegradable surfactants. In this study, the physicochemical properties of two APG surfactants under high-temperature and high-salinity conditions were evaluated. The effectiveness of the surfactants as imbibition agents on improving oil production in carbonate reservoirs was investigated. A formulation with ultra-low interfacial tension (IFT) was introduced and the mechanisms resulting in such low IFT were probed and discussed. Two APG surfactants were studied. Compatibility was evaluated by the transparency in brine solutions after aging. IFT was measured with the formulations of surfactant/additives. The morphology of network formed by surfactant/additives was observed via scanning electron microscope (SEM). The static adsorption of the APGs onto carbonate powder was determined by total organic carbon (TOC) analyzer. The contact angle of oil droplet on surface of carbonate core was measured in surfactant solution. The oil production via spontaneous imbibition of water in carbonate core was obtained using Amott cell. An imbibition simulation model was validated by the experimental results using UTCHEM simulator. Both surfactants APG-1 and APG-2 exhibited excellent compatibility with the simulated high salinity water at reservoir temperature. They also demonstrated low static adsorption on carbonate reservoir. The surfactant containing larger hydrophobic carbons (APG-1) showed more incremental oil production potential than the other one bearing shorter hydrophobic chain (APG-2). At a concentration of 0.2 wt%, APG-1 yielded a low IFT in the order of 10-2 mN/m and an ultra-low IFT in the order of 10-3 mN/m was obtained upon addition of a small amount of additives. SEM pictures indicated that APG-1 and the additives synergistically generated a more compact structure via interaction between hydrophobic moieties of the chemicals compared to the aggregated structure formed by APG-1 alone. Such an effect could eventually lead to a decrease in IFT between oil and water. APG-1 slightly altered the wettability of carbonate core surface toward water-wet. The experimental results of spontaneous imbibition tests showed an oil production of 28% and 21% by APG-1 and APG-2, respectively. After parameter tuning, the yielded curves from numerical simulation by UTCHEM simulator perfectly matched the experimental data. A new APG-based formulation was designed with an ultra-low IFT resulting in a much more compact amphiphilic structure along the oil-water interface. This study shows a great potential of APG surfactants and the relevant derivative formulations in improving oil production application for high-temperature and high-salinity carbonate reservoirs.
Imbibition
Brine
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Abstract Surfactant flooding has widely been used as one of the chemically enhanced oil recovery (EOR) techniques. Surfactants majorly influence the interfacial tension, γ, between oil and brine phase and control capillary number and relative permeability behavior and, thus, influence ultimate recovery. Additives, such as nanoparticles, are known to affect surfactant properties and are regarded as promising EOR agents. However, their detailed interactions with surfactants are not well understood. Thus, in this work, we examined the influence of silica nanoparticles on the ability of surfactants to lower γ and to increase viscosity at various temperatures and salinities. Results show that the presence of nanoparticles decreased γ between n‐decane and various surfactant formulations by up to 20%. It was found that γ of nanoparticles–surfactant solutions passed through a minimum at 35 °C when salt was added. Furthermore, the viscosity of cationic surfactant solutions increased at specific salt (1.5 wt.%) and nanoparticle (0.05 wt.%) concentrations. Results illustrate that selected nanoparticles–surfactant formulations appear very promising for EOR as they can lower brine/n‐decane interfacial tension and act as viscosity modifiers of the injected fluids.
Brine
Decane
Aqueous two-phase system
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Abstract Experimental studies have been conducted to explore the interfacial tensions in an acid-free oil/alkali/surfactant system, and sodium hydroxide is used as the alkali chemical. The influences of salt and alkali on the interfacial activity of oil/surfactant systems were studied by the measurement of interfacial tensions and partition coefficients. The results showed that in an appropriate concentration range, an ultra-low interfacial tension could be obtained in the acid-free oil/alkali/surfactant system, and compared with the salt; the function of alkali for lowering interfacial tensions and improving partition coefficients is more significant.
Sodium hydroxide
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