Interfacial Tension Properties Research Articles

Evaluation of the Synergistic Oil Displacement Effect of a CO2 Low Interfacial Tension Viscosity-Increasing System in Ultra-Low Permeability Reservoirs

In addressing the issue of poor control over gas permeability during the CO2 flooding process in ultra-low permeability reservoirs, this study proposes the use of a low interfacial tension viscosity-increasing system as a substitute for water in CO2–water alternating flooding to enhance CO2 mobility control and increase oil recovery. The performance of the system was evaluated through tests of viscosity, interfacial tension, wettability, and emulsification properties, and the injection behavior and gas channeling prevention effect of the viscosity-increasing system with CO2 alternate flooding were investigated. The results indicate that the low interfacial tension viscosity-increasing fluid exhibits good thickening properties, interfacial activity, hydrophilic wettability, and oil–water emulsification performance, also demonstrating strong environmental adaptability. The CO2–low interfacial tension viscosity-increasing fluid alternate flooding shows good injectivity in ultra-low permeability cores (1.085 mD). Following water flooding in heterogeneous ultra-low permeability cores, the implementation of CO2 low interfacial tension viscosity-increasing fluid alternate flooding can lead to a 15.91% increase in overall recovery compared to water flooding, outperforming CO2 flooding and CO2–water alternating flooding. The mechanisms by which the CO2 low interfacial tension viscosity-increasing fluid enhances oil recovery include reducing interfacial tension, improving mobility ratio, altering rock surface wettability, and emulsification effects. The low interfacial tension viscosity-increasing systems demonstrate effective mobility control and oil displacement capabilities and synergistically enhance the efficiency of CO2, presenting potential application prospects in the development of CO2 flooding in ultra-low permeability reservoirs.

Comparative study of nanoemulsion and micelle formed by surfactants containing benzene ring for spontaneous imbibition displacement

Nanoemulsion has a wide range of applications in oilfield chemistry due to its unique nanoscale size, excellent kinetic stability and high specific surface area. In this paper, a novel nanoemulsion oil flooding system was prepared using anionic surfactant sodium dodecyl benzene sulfonate (SDBS), the nonionic surfactant alkylphenol ethoxylates (OP-10), kerosene, n-butanol and deionized water. The particle size, Zeta potential, interfacial tension (IFT) and wettability properties were evaluated in the laboratory. The displacement performance of nanoemulsion was evaluated by the spontaneous imbibition experiment. Meanwhile, it compared with the same concentration of SDBS + OP-10 + n-butanol (SOB) system. The results showed that the particle size of the nanoemulsion was 70 ∼ 100 nm. When the concentration of nanoemulsion was 0.10 %, the oil–water IFT could reach 0.091 mN/m. The spontaneous imbibition oil recovery of the nanoemulsion (0.10 wt%) could reach 33.20 %, which was 23.02 % higher than that of SOB system. We also research the spontaneous imbibition displacement mechanism of nanoemulsion and micelle in low-permeability reservoirs. This paper will help to select the best oil displacement agent for the design of enhanced oil recovery (EOR) projects and promote the application of oil displacement agent in oilfield.

Interfacial shear and elongational rheology of immiscible multi-micro-nanolayered polymers: contribution for probing the effect of highly mismatched viscoelastic properties and modeling interfacial tension properties

Interfacial shear and elongational rheology of immiscible multi-micro-nanolayered polymers: contribution for probing the effect of highly mismatched viscoelastic properties and modeling interfacial tension properties

Introducing a graphical user interface for dynamic contact angle determination

Contact angle goniometry is an important characterization technique that can determine crucial information, such as the wettability, interfacial tension, and adhesion properties of solid and liquid surfaces alike. However, while this technique is already widespread, the by-hand analysis process of elucidating the advancing and receding contact angles (ARCAs) from the actual data set has many pitfalls and is fraught with human error. In this article, we introduce a graphical user interface (GUI) called ARCA Finder that drastically simplifies the analysis process by displaying the contact angle data in a novel perspective and aiding the user to determine the most accurate measurement from the available data based on the full definition of the dynamic contact angles. The goal of this invention is to improve measurement accuracy by reducing human error in goniometry, while also improving the repeatability of measurements among different researchers. By testing this approach alongside by-hand analysis on both synthetic and real dynamic contact angle videos, our results demonstrate a noticeable difference in the measured values, which suggests that the ARCA Finder GUI improves the measurement accuracy compared to the standard approach.

High internal phase Pickering emulsions stabilized by modified sturgeon myofibrillar protein for quercetin delivery

In this study, the modified sturgeon myofibrillar protein was prepared by the combination of malondialdehyde and ultrasonic induction and used as the emulsifier to form a stable high internal phase Pickering emulsion (HIPPEs) with internal phase up to 75%. The results showed that combined modification reduced the fluorescence intensity, enhanced the surface hydrophobicity, changed the secondary structure, and made the protein particles smooth. The confocal laser scanning microscopy confirmed the formation of a stable HIPPEs. The interfacial tension and rheological properties of protein stabilized HIPPEs were improved by the combined modification and the encapsulation efficiency of quercetin reached 89.32%. In vitro digestion showed that the combined modified protein-stabilized HIPPEs significantly improved the rate of lipid digestion and the bioavailability of quercetin while reducing the degradation of quercetin. The findings indicated that the utilization of modified sturgeon myofibrillar protein to stabilize HIPPEs hold significant promise for various biological applications, owing to its capacity as a carrier for the regulated discharge of bioactive agents.

A simplified lattice Boltzmann model for two-phase electro-hydrodynamics flows and its application to simulations of droplet deformation in electric field

This paper proposes a numerical scheme within the lattice Boltzmann framework for effective simulations of two-phase electro-hydrodynamic (EHD) flows, in which the simplified multiphase lattice Boltzmann method serves as the flow solver and a leaky dielectric model is utilized to recover electric potential equation. The resultant formulations present direct evolution of macroscopic variables, due to which the present method outperforms the conventional lattice Boltzmann method in terms of memory cost and boundary treatment. Numerical validations are first carried out under the same parametric conditions as the benchmarking experimental studies with the conductivity ratio ranging from 0.03 to 1000, demonstrating that the present method is a practical and accurate tool to study large-conductivity-ratio two-phase EHD flows in scientific applications. Through the comparison with previous theoretical and numerical studies, the performance of the present method is further evaluated by varying physical parameters such as electric capillary number, electric field strength, interfacial tension, and electrical properties of liquids. The good agreements with the reference data confirm the accuracy and robustness of the proposed method. Additional studies of the dynamics of a deformed droplet in uniform electric field are carried out using the validated method. Specifically, we conduct a close numerical examination on the effect of the electrical conductivity ratio and permittivity ratio on the electric forces, and highlight the role of the dielectric electrophoretic force and the Coulomb force on the electric forces the deformation of a leaky dielectric droplet in the electrical conductivity ratio and the permittivity ratio phase diagram.

The effects of SDS, APG, and DTAB surfactants on the morphology of micro-nano RDX particles prepared in a microfluidic reactor

Abstract The effects of different surfactants on the morphology of 1,3,5-trinitro-1,3,5-triazinane (RDX) micro-nanoparticles prepared by solvent/non-solvent method in a microfluidic reactor were investigated. Alkyl polyglycoside (APG), sodium dodecyl sulphate (SDS) and dodecyltrimethylammonium bromide (DTAB) were selected as non-solvents. The surface tension and interfacial tension (IFT) properties of SDS, APG and DTAB were investigated. Compared to DTAB and SDS, the APG could effectively reduce the interfacial tension to 10−2 mN/m and exhibited better surface tension. The RDX prepared with different surfactants were analysed by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and Fourier transform infrared spectrometry (FTIR). The results showed that the different surfactants could significantly improve the dispersion effect of RDX and the crystal morphology was uniform and stable.

Molecular Dynamics Study of Interfacial Properties for Crude Oil with Pure and Impure CH4

Gas injection has received increasing attention as one of the key technologies to enhance oil recovery. When gas is dissolved in crude oil, it will accelerate the flow of crude oil by reducing the density, viscosity, interfacial tension (IFT), and other properties of crude oil, so IFT is one of the main factors affecting the recovery of the gas drive. The interfacial properties of CH4, one of the principal associated hydrocarbon gases, with crude oil remain unclear. In this study, molecular dynamics (MD) simulations were used to determine the IFTs of pure and impure CH4 with n-decane as well as the IFTs of the ternary systems CH4 + n-hexane + n-decane and CH4 + n-decane + n-nonadecane. Additionally, investigating factors including pressure, temperature, gas composition, and crude oil composition reveals the mechanisms affecting the interfacial properties of CH4 and crude oil. The results demonstrate that CO2 significantly lowers the IFT of CH4 + n-decane; the effect of crude oil components on IFT varies with the properties of the crude oil and, generally speaking, IFT is greater for crude oils containing heavy components than for those containing light components; the effect of temperature on the IFT of the CH4 + n-decane system is more pronounced at low pressure and decreases with increasing pressure. This study contributes to understanding the behavior of CH4 and oil systems in the formation and could be used to enhance the oil recovery technology.

Effects of the number of cationic sites on the surface/interfacial activity and application properties of quaternary ammonium surfactants

A novel Gemini surfactant containing four cationic sites (N,N′-bis((2-hydroxypropyl) dodecyl-tetradecyl dimethyl ammonium chloride)-N,N,N′,N′-tetramethyl-N,N′-hexamethylene diammonium chloride, TC-GS) was synthesized and its structure was confirmed by FT-IR, 1H NMR, 13C NMR, and MALDI-TOF-MS analysis. The equilibrium/dynamic surface tension, oil-water interfacial tension, and antistatic/antibacterial properties of TC-GS were measured and compared with a Gemini surfactant containing two cation sites (Hexamethylene-1,2-bis(dodecyl-tetradecyldimethylammonium chloride, DC-GS) and a single-chain surfactant containing one cationic site (Dodecyl-tetradecyltrimethyl ammonium chloride, DTAC) to investigate the effect of the number of cationic sites on the surface/interfacial properties and application performance. The results showed that TC-GS exhibited lower critical micelle concentration (CMC) and faster dynamic adsorption rate than that of DC-GS and DTAC. And according to the measurement of oil-water interfacial tension, the TC-GS presented the superior ability to reduce the kerosene-water interfacial tension, and only of which was able to reach the ultra-low values (10−3 mN/m) at lower concentrations. In addition, TC-GS shows better antistatic performance on polyester fabrics and has superior antibacterial ability against both Gram-negative and Gram-positive bacteria. The study reveals that quaternary ammonium surfactants containing more cationic sites are favorable to improving the surface and interfacial tension properties and application performance.

Targeted modifications of citrus pectin to improve interfacial properties and the impact on emulsion stability

In the present work, three specific low weight average molecular weight (M w ) demethoxylated citrus pectin derived compounds (oligosaccharides) (CP 25 kDa , CP 3 kDa and CP 3.8 kDa ) were generated by means of enzymatic degradation and subsequent chemical demethylesterification of three starting pectin materials (CP74 144 kDa , CP53 151 kDa and CP38 116 kDa , respectively). These pectin oligosaccharides were structurally characterized, evaluated for their physicochemical properties, and their emulsifying and emulsion stabilizing (E F E S ) potential. In terms of structure, significant differences in M w , degree of methylesterification (DM), monosaccharide and protein contents were observed between the initial and the generated pectin-derived samples. Interestingly, upon evaluation of the physicochemical properties of the generated pectin-derived materials, it was observed they exhibited considerably improved interfacial tension properties in comparison to the initial pectin samples. Furthermore, all pectin materials were negatively charged to similar extents. On the negative side, the low viscosity of the generated pectin compounds was observed to significantly hinder their E F E S properties. Upon refrigerated storage of the pectin emulsions, it was observed that the initial pectin materials (at pH 2.5) exhibited better E F E S potential in comparison to the generated pectin materials, despite the superior interfacial potential of the latter samples. This was mainly ascribed to the higher viscosity of the non-degraded pectin samples, in turn attributed to their larger M w . Overall, the results obtained indicated that the M w and DM of the polymer played an important role in the interfacial tension properties of pectin. However, viscosity of the continuous phase of the dispersion is a critical factor in the E F E S potential of pectin. • All modified citrus pectin samples (M w <25 kDa) evaluated exhibited enhanced surface activity. • Coalescence and flocculation were considered the main destabilizing mechanisms in the emulsions formulated with low M w (<25 kDa) pectins. • Differences in viscosity increasing capacity, among the mother and modified pectin samples, are suggested to be the main factor influencing the stability of the formulated emulsions.

Influences of asphaltene subfractions with different polarities on hydrate growth at water/oil interface

As a kind of typical natural surface-active substance, asphaltenes can not only lead to deposition and plugging accidents, but also affect the formation and slurry flow of hydrate during deep-sea oil and gas transportation process. This paper investigates the polarity effects of the asphaltene subfractions on the growth process of hydrate particles at oil–water interface. First of all, four asphaltene subfractions with different polarities were extracted by the solvent precipitation method. Then, the dynamic interfacial tension and dilational viscoelastic properties were measured to characterize the oil–water interfacial films adsorbed with the different asphaltene subfractions. Following that, the hydrate growth experiment was carried out using a self-designed atmospheric visualization unit. Specifically, the transformation process of a single droplet into a hydrate particle in oil phase containing asphaltenes was studied to determine the influence of asphaltene subfractions on hydrate growth. The change degree of particle morphology and the growth rate of hydrate shells were used as two analysis indexes. The results show that the change degree of particle morphology and the growth rate of hydrate shells were both affected by the dispersion state and interfacial adsorption amount of the asphaltene subfractions. Under the combined action of migration and surface covering, the asphaltene subfractions have different effects on hydrate growth process at various concentrations. At the concentration of 0.01 mg/g and 0.1 mg/g, a looser interfacial adsorption layer will result in a large effective interfacial area, i.e., a weaker mass transfer hindrance. At this time, the structural strength of the interfacial film is low. At the concentration of 0.2 mg/g, however, the transformation rate of the hydrate shells is accelerated owing to the trapped oil phase, so the structural strength of the interfacial film is enhanced. Therefore, with the increase of the asphaltene concentration, the hydrate particles are easier to maintain their original state.

Date-Leaf Carbon Particles for Green Enhanced Oil Recovery.

Green enhanced oil recovery (GEOR) is an environmentally friendly enhanced oil recovery (EOR) process involving the injection of green fluids to improve macroscopic and microscopic sweep efficiencies while boosting tertiary oil production. Carbon nanomaterials such as graphene, carbon nanotube (CNT), and carbon dots have gained interest for their superior ability to increase oil recovery. These particles have been successfully tested in EOR, although they are expensive and do not extend to GEOR. In addition, the application of carbon particles in the GEOR method is not well understood yet, requiring thorough documentation. The goals of this work are to develop carbon nanoparticles from biomass and explore their role in GEOR. The carbon nanoparticles were prepared from date leaves, which are inexpensive biomass, through pyrolysis and ball-milling methods. The synthesized carbon nanomaterials were characterized using the standard process. Three formulations of functionalized and non-functionalized date-leaf carbon nanoparticle (DLCNP) solutions were chosen for core floods based on phase behavior and interfacial tension (IFT) properties to examine their potential for smart water and green chemical flooding. The carboxylated DLCNP was mixed with distilled water in the first formulation to be tested for smart water flood in the sandstone core. After water flooding, this formulation recovered 9% incremental oil of the oil initially in place. In contrast, non-functionalized DLCNP formulated with (the biodegradable) surfactant alkyl polyglycoside and NaCl produced 18% more tertiary oil than the CNT. This work thus provides new green chemical agents and formulations for EOR applications so that oil can be produced more economically and sustainably.

Study on the Synergistic Effects between Petroleum Sulfonate and a Nonionic–Anionic Surfactant for Enhanced Oil Recovery

Nonionic–anionic surfactants are expected to be applied in chemical flooding due to their important properties such as ultralow IFT values, good salt tolerance, and no chromatographic separation in porous media. In this study, a new type of nonionic–anionic–hydrophobic group structure surfactant N, N-dihydroxyethylalkylamide carboxylate (EAMC) was synthesized. The synergistic effects between petroleum sulfonate (KPS) and EAMC in reducing interfacial tension (IFT) and emulsification properties were studied. The influences of salt, alkali and Ca2+ on the IFTs of surfactant solutions were also investigated. One-dimensional core flooding experiments were used to characterize the enhanced oil recovery capability of the KPS and EAMC mixed system. The experimental results show that both EAMC and KPS have high interfacial activity and can reduce IFTs to about 0.01 mN/m order of magnitude against decane at optimized concentrations. The area occupied by the hydrophilic group of EAMC on the interface is smaller than that of its own hydrophobic group. The interfacial film formed by EAMC alone is relatively loose. The IFTs of KPS containing different structure petroleum sulfonates is affected by the difference in the adsorption rate of petroleum sulfonates on the interface, which shows that both the dynamic and equilibrium interfacial tensions can have the lowest values. However, the IFTs of the EAMC solutions against crude oil can be reduced to ultralow values because the mixed tight adsorption film is formed by EAMC and crude oil fraction molecules with synergistic effect. On the other hand, the KPS molecule has a hydrophobic part with large size and no synergism with crude oil fractions can be observed in the solutions containing only KPS. The combination of EAMC and KPS shows synergistic effect, namely ultralow IFT values, good emulsification properties, high alkali tolerance, and good salt and Ca2+ tolerance during a wide percentage range of EAMC. The best formula of EAMC and KPS system can be applied for EOR after polymer flooding. The studies in this paper are helpful for the design and application of a chemical flooding formula with nonionic–anionic–hydrophobic group structure surfactants.

Сурфактантное состояние синовиальной жидкости у больных ревматоидным гонитом

По сравнению с больными остеоартрозом со вторичным синовитом коленных суставов (контрольная группа) при ревматоидном гоните наблюдается уменьшение содержания в синовиальной жидкости общего белка, нитритов, мочевой и молочной кислоты на фоне повышения уровней глюкозы и С-реактивного протеина, причем на интегральное сурфактантное состояние синовии влияют степень активности и рентгенологическая стадия заболевания, наличие дигитального артериита и поражения эндокарда. Кроме того содержание общего белка и β2-микроглобулина зависит соответственно от индексов тяжести течения и прогрессирования заболевания, а с поверхностно-активными веществами тесно связаны динамическое межфазное натяжение, вязкие, упругие и вязкоэластичные адсорб­ционно-реологические свойства суставного ликвора.

Synergism and foam stability in a binary mixture of tea saponin derived from Camellia oleifera Abel and Sodium Lauryl Ether Sulfate

Sodium Lauryl Ether Sulfate, AES, is an anionic surfactant containing ethylene oxide groups, which is widely used in various cosmetic. In this work we investigate the synergism and foam stability in a binary mixture of tea saponin (TS) and AES to promote the development of new formulations and reduce the use of synthetic surfactants in commercial products. The effect of TS addition on interfacial behavior was investigated by interfacial tension (γ) and foam properties, and the interfacial activity was analyzed on different fluid/fluid interfaces at different environments. The results showed that the mixtures of TS with AES displayed synergism in critical micelle concentration (cmc), such as the interaction parameter and thermodynamic parameter. Low concentration of TS addition not only caused the decrease of γcmc, but also improved the stability of the foam. The stability of foams has been interpreted on the basis of bubble distribution size and contact angle. Further study revealed that the interfacial activity of the AES/TS mixture was stable at high temperatures, in the presence of mono (Na+) and divalent (Ca2+ and Mg2+) counterions, and at a pH of 3–11.

Experimental study on the performance of emulsions produced during ASP flooding

ASP (Alkaline/Surfactant/Polymer) flooding is one of the most promising techniques that has proven to have successful application in several laboratory and pilot tests. However, the formation of persistent and stable emulsions is one of the associated problems with ASP flooding. The present work investigated the effect of sodium carbonate alkaline, Alpha Olefin Sulfonate (AOS) surfactant, and GLP100 polymer on produced crude oil emulsion. The study was conducted by measuring the emulsion stability in terms of water separation and rag layer volume using a TurbiScan analyzer, the dispersed droplet size using cross-polarization microscopy, the interfacial tension using spinning drop tensiometer, and rheological properties using rheometer. The experimental results have shown that AOS presence increased the emulsion stability only when its concentration is above 100 ppm. Meanwhile, below 100 ppm, the presence of AOS promoted water separation and reduced the rag layer volume. In a less significant manner, a high concentration of sodium carbonate alkali increased the stability of the emulsion. The use of GLP100 Polymer has shown substantial ability in promoting water separation and reducing the rag layer volume to a minimal level. It is believed that the outcomes of this work will aid in developing a suitable destabilization process to enhance the oil–water separation and produced water treatment from ASP flooding in the oil production fields. Further investigations on AS, AP, SP as well as the ASP's combined effect on emulsion stability, droplet size, interfacial tension and rheological properties are highly recommended to support the decision-makers on the EOR implementations with chemical additives.

Surfactant properties of a biomimetic antifreeze polymer admixture for improved freeze-thaw durability of concrete

Recently, a novel bioinspired approach for improving freeze–thaw resistance of concrete was proposed as an alternative to traditional air entrainment. The mechanism is based on ice recrystallization inhibition (IRI) activity displayed by antifreeze proteins and synthetic, biomimetic replicates, like nonionic polyethylene glycol–graft–polyvinyl alcohol (PEG-PVA), which can be added as a polymeric admixture to concrete in the fresh state. To further substantiate the mechanistic underpinnings of the air-entraining agent (AEA) alternative, this work measures and reports the foam stability and interfacial surface tension properties of nonionic PEG-PVA. Foam stability and tensiometry measurements of PEG-PVA were quantified and compared to a conventional anionic AEA, MasterAir (MA). Results demonstrate that PEG-PVA requires much higher concentrations (0.77–2.8% by weight of cement) to form a stable foam system in comparison to the AEA (0.027–0.19%). The results correlated well with foam stability measurements, which showed PEG-PVA’s inability to form long-lasting stable foams in comparison to MA. Tensiometry measurements also revealed that high concentrations (10–60 g/L) of PEG-PVA were required to reduce the surface tension of water in comparison to MA (0.015–0.045 g/L), indicating that PEG-PVA neither acts as a surfactant nor readily self-assembles into micelles at concentrations that proved to provide freeze–thaw resistance. Nevertheless, PEG-PVA-modified concrete showed similar resistance to MA-modified concrete in freeze–thaw cycling at concentrations as low as 0.066% by weight of cement while entraining only minimal amounts of air, suggesting that the freeze–thaw resistance is due at least in part to the IRI activity of PEG-PVA instead of its ability to entrain a proper air void system.

Towards efficient solar demulsification (I): A solar electrical role on interfacial film of emulsions

Oil/water separation has become a significant issue since emulsions are detected in many industrial wastewater and severely threaten the ecological environment. Developing separation technique driven by solar energy with high separation efficiency is quite meaningful and challenging. In this work, solar electrical role on an interfacial film of emulsions was developed for efficient oil/water separation. Emulsified oil/water droplets from the ASP flooding were chosen to characterize the influence of solar electrical role on demulsification. Droplet size distribution, zeta potential, interfacial tension, viscosity, microscope image, and rheological properties were systematically studied to explore the mechanism of electrical role on the instability of oil droplets. Experimental results indicate solar electrical role on the oil-water interface can change the properties of the interface, help the oil-water emulsion instability, and promote oil-water separation. The instability mechanism of the emulsion can be summarized as the following. Firstly, the charged oil/water droplets interfere with the original electric field, which generates a force along with the droplet's tangential direction. Secondly, the force drives charged groups to radially migrate away from the electrode, which causes the entangled polymer to loosen, expand, and rearrange interface charges, resulting in decreasing in the rigidity and zeta potential. Thirdly, the force also promotes the electrohydrodynamic flow of oil/water droplets. The adjacent oil/water droplets mutually entrained in electrohydrodynamic fluid flow, resulting in coalescence. Furthermore, the interface-active components can be electrochemically oxidized to small molecular. The in-depth research of solar electrical role on interfacial film provides theoretical support for coupling of solar photo effect and thermal effect, to obtain highly efficient solar demulsification.

Improvement of Heavy Oil Recovery by Nonionic Surfactant/Alcohol Flooding in Light of the Alkane Carbon Number and Interfacial Tension Properties

In this work, we prepared nonionic surfactants from waste cooking oil materials. Hydrolysis was carried out for palm and palm kernel waste cooking oils to get a mixture of free fatty acids. The mixture of free acids was esterified with sorbitan and then ethoxylated at different ethylene oxide units. Two surfactants exhibited promising surface-active properties among the six prepared surfactants based on the results of surface tension. The interfacial tension (IFT) around the critical micelle concentration was measured against a series of n-hydrocarbon to detect the minimum alkane carbon number (ACN) (Πmin) for each of these surfactants. The effect of normal and branched alcohols on Πmin was also studied to design the surfactant/alcohol mixture for the chemical flooding process. From the results of IFT, the ethoxylated ester derivatives of palm kernel fatty acids (EPK-20) exhibited minimum IFT γmin (0.06 mN m–1) at Πmin equal to 12, and the ethoxylated ester derivatives of palm fatty acids (EP-40) achieved γmin equal to 0.09 mN m–1 at Πmin of 10. Branched alcohols shifted Πmin to a higher value to reach the equivalent ACN of the crude oil and decrease the IFT to lower values. The flooding process showed that the maximum oil recovery was obtained by EPK-20 (54.2% when used purely and 66.2% when used with isoamyl alcohol). In comparison, EP-40 exhibited that oil recovery equals 46% without alcohol and 46.4% with iso-butanol alcohol. The results were interpreted and discussed based on interfacial properties, wettability alteration, and the ACN.

Strontium-based low salinity water as an IOR/EOR method: Oil-brine interaction

Strontium-based injection water for enhanced oil recovery has been neglected due to the low solubility of the cation in water. However, challenging reservoirs like those in the Brazilian pre-salt region demand non-conventional solutions to improve oil production. This work shows for the first time that the strontium cation in low salinity water solutions shall be henceforth considered as a potential component in the development of enhanced/improved oil recovery (EOR/IOR) studies. Acidic and non-acidic model oils and real crude oils from Brazilian post-salt and pre-salt fields were used for this study. The oil/brine interfacial tension and viscoelastic properties of the interfacial films were measured by an ascendant drop tensiometer. The results showed that strontium presents the highest interfacial activity among the other alkaline-earth metals. Also, the strontium-based low salinity water produced the most elastic interfacial film, which is desired for the improvement of oil volumetric sweeping promoted by water flooding. Nonetheless, it is worth highlighting that further studies including core flooding experiments must be performed to assess the strontium effect on the crude oil outflow through reservoir pores as well as the influence of water/oil/rock interactions upon it.