Interfacial Tension Reduction Research Articles

Investigating the mechanism of interfacial tension reduction through the combination of low-salinity water and bacteria

In the enhanced oil recovery (EOR) process, interfacial tension (IFT) has become a crucial factor because of its impact on the recovery of residual oil. The use of surfactants and biosurfactants can reduce IFT and enhance oil recovery by decreasing it. Asphaltene in crude oil has the structural ability to act as a surface-active material. In microbial-enhanced oil recovery (MEOR), biosurfactant production, even in small amounts, is a significant mechanism that reduces IFT. This study aimed to investigate fluid/fluid interaction by combining low biosurfactant values and low-salinity water using NaCl, MgCl2, and CaCl2 salts at concentrations of 0, 1000, and 5000 ppm, along with Geobacillus stearothermophilus. By evaluating the IFT, this study investigated different percentages of 0, 1, and 5 wt.% of varying asphaltene with aqueous bulk containing low-salinity water and its combination with bacteria. The results indicated G. Stearothermophilus led to the formation of biosurfactants, resulting in a reduction in IFT for both acidic and basic asphaltene. Moreover, the interaction between asphaltene and G. Stearothermophilus with higher asphaltene percentages showed a decrease in IFT under both acidic and basic conditions. Additionally, the study found that the interaction between acidic asphaltene and G. stearothermophilus, in the presence of CaCl2, NaCl, and MgCl2 salts, resulted in a higher formation of biosurfactants and intrinsic surfactants at the interface of the two phases, in contrast to the interaction involving basic asphaltene. These findings emphasize the dependence of the interactions between asphaltene and G. Stearothermophilus, salt, and bacteria on the specific type and concentration of asphaltene.

Investigation of ionic liquid adsorption and interfacial tension reduction using different crude oils; effects of salts, ionic liquid, and pH

The results revealed the significant effect of NaCl, KCl, CaCl2, MgCl2, CaSO4, MgSO4, and Na2SO4 and pH values of 3.5–11 on the interfacial tension (IFT) reduction using three types of neutral, acidic, and basic crude oils, especially for acidic crude oil (crude oil II) as the pH was changed from 3.5 to 11 (due to saponification process). The findings showed the highest impact of pH on the IFT of crude oil II with a reducing trend, especially for the pH 11 when no salts exist. The results revealed that the salts except MgCl2 and CaCl2 led to a similar IFT variation trend for the case of distilled water/crude oil II. For the MgCl2 and CaCl2 solutions, a shifting point for IFT values was inevitable. Besides, the dissolution of 1-dodecyl-3-methyl imidazolium chloride ([C12mim][Cl]) with a concentration of 100–1000 ppm eliminates the effect of pH on IFT which leads to a reducing trend for all the examined crude oils with minimum IFT of 0.08 mN/m. Finally, the [C12mim][Cl] adsorption (under pH values) for crude oils using only Na2SO4 was measured and the minimum adsorption of 0.41 mg surfactant/g Rock under the light of saponification process was obtained.

Effects of nano-smart water on enhanced oil recovery in carbonate reservoirs: Interfacial tension reduction and wettability alteration

Several studies have revealed that nanofluid and smart water flooding are cost-effective methods, considering the effect of nanoparticles and potential determining ions (PDIs) for enhanced oil recovery in carbonated reservoirs. This study presents the performance of nano-smart water synthesized with surface-modified SiO2 nanoparticles dispersed in PDI-controlled seawater (SW), ensuring dispersion stability in high-temperature and high-salinity reservoirs. The interfacial tension (IFT) and contact angle of the oil/nano-smart water/carbonate rock system were measured using kerosene as an oil phase. At this time, nanoparticle concentrations ranged from 0.5 to 3wt.% and PDI concentrations ranged from 1,000 to 5,000 ppm, such as KCl, MgCl2, MgSO4, and K2SO4. In addition, the IFT and contact angle of SW, low salinity water (LSW), and nanofluid were measured for comparison. It was observed that at nanoparticle concentrations higher than 1wt.%, the IFT values of nano-smart water remained constant or decreased slightly to below 31.91 mN/m compared with nanofluids at 32.18 mN/m, regardless of PDI type and concentration. This indicates that using nano-smart water instead of LSW and SW is expected to reduce the IFT in the oil/water system. The contact angle measurements revealed that the wettability index is 2.57 to 5.07 times higher in nano-smart water than in nanofluids. This implies that wettability alteration is accelerated by the synergistic effect of PDIs and nanoparticles. Specifically, PDI control with MgSO4 or K2SO4 is highly effective in changing the contact angle of carbonate from strongly oil-wet to strongly water-wet due to the ion exchange reaction of SO42- in oil/water/carbonate rock system. The nano-smart water used in this study is expected to be utilized as an injection fluid under harsh conditions for enhanced oil recovery.

Synergistic collaborations between surfactant and polymer for in-situ emulsification and mobility control to enhance heavy oil recovery

Surfactant-polymer (SP) combined systems is an effective nonthermal method to enhance the heavy oil recovery, through in-situ emulsification and mobility control mechanisms. In this study, a novel SP system was developed using 0.2 wt% anionic surfactant (alkyl naphthol polyoxyethylene ether sulfonate, ANES) and 0.1 wt% polymer (partially hydrolyzed polyacrylamide, HPAM). The SP system had viscosity reduction rate of ∼ 98 %, viscosity ratio of oil to displaced water (μo/μd) of ∼ 3.95 and IFT of ∼ 0.29 mN/m, beneficial for decreasing the mobility ratio of water to heavy oil. Then, the applied performances including emulsion morphologies and stability, wettability alteration ability were systematically characterized. The results showed that the freshly O/W emulsions formed by SP system displayed uniform droplet size distribution, as well as high stability with tight interfacial film. In addition, the SP system exhibited excellent wettability alteration property with low contact angle of 18.3°. The synergistic collaboration mechanisms of surfactant and polymer include heavy oil–water interfacial tension reduction, in-situ emulsification, oil-viscosity reduction and water-viscosity increase. Finally, the static oil washing and dynamic sand-pack flooding experiments showed that the SP system exhibited high oil washing efficiency (62.89 %) and enhanced oil recovery efficiency (56.9 %) with improving the mobility controllability after the primary water-flooding process. This study indicated that the synergistic collaborations between surfactant and polymer had great potential to enhance the heavy oil recovery.

Advanced machine learning-based modeling of interfacial tension in the crude oil-brine-diethyl ether system: Insights into the effects of temperature and salinity

Solvent injection, a well-established method for enhanced oil recovery (EOR), has demonstrated significant improvements in oil recovery when compared with conventional water flooding techniques. The interfacial tension (IFT) is pivotal in determining the displacement efficiency and overall performance of innovative techniques like dimethyl ether-enhanced waterflooding (DEW), which has gained substantial attention in recent years. In this study, following laboratory measurements of IFT, six advanced machine learning (ML) techniques were employed: Generalized Linear Model (GLM), Generalized Additive Model (GAM), Random Forest (RF), Support Vector Machine (SVM), Extreme Gradient Boosting (XGBoost), and Boosted Regression Tree (BRT) to model the IFT in both oil-brine and oil-brine-diethyl ether (DEE) systems. The analysis is based on an extensive dataset comprising 7,017 data points for oil-brine and 6,949 data points for oil-brine-DEE systems obtained from experimental studies. The findings indicate that the developed RF model excels in predicting IFT, boasting a remarkable coefficient of determination (R2 = 0.99) along with the lowest root mean squared error (RMSE = 0.2), mean squared error (MSE = 0.04), and mean absolute error (MAE = 0.13). The study underscores the significance of optimizing salinity levels to achieve the most substantial reduction in IFT. This reduction is attributed to the enhanced migration of polar components, such as asphaltene molecules, to the interface of the oil-brine system. Moreover, the research highlights a synergistic decrease in IFT when both DEE and soluble ions are present, resulting in the lowest IFT at around 2 mN/m in 40,000 ppm salinity (S2) at 70 °C (T3). This indicates that the adsorption of DEE at the water–oil interface forms a layer capable of adsorbing ions, thereby enhancing the layer's thickness. As a result, the oil–solvent-ion layer becomes thicker compared to the oil-ion layer, leading to the maximum decrease in IFT. Additionally, with increasing temperature up to 70 °C, the IFT of both systems demonstrated a downward trend, as evidenced by all experiments. The outcomes of this study have the potential to enhance our comprehension of the underlying mechanisms involved in water-soluble solvent EOR techniques.

Ionic liquids adsorption and interfacial tension reduction for synthetic resinous and asphaltenic oils: salinity and pH effects

The effects of sulfate salts under low and high salinity conditions and pH of 3.5–11 on interfacial tension (IFT) reduction and IL adsorption using resinous (RSO) and asphaltenic (8 wt/wt%) synthetic oils are investigated. The measurements showed the increasing effect of pH on the IFT of RSO/DW from 23.5 to 27.3 mN/m (pH = 3.5 → 7) in the first place and a reducing effect (0.4 mN/m) if pH = 7 → 11. Using a high concentration of 50,000 ppm for MgSO4, and Na2SO4 revealed an extensive IFT reduction for a pH value of 11 with the value of 0.20 mN/m for Na2SO4. The measured IFT values showed the significant impact of IL (500 ppm) on the IFT (minimum value of 0.01 mN/m for RSO/50,000 Na2SO4 + 500 ppm 1-decyl-3-methyl imidazolium triflate ([C10mim][TfO])) for pH = 11. The IL adsorption measurements showed the role of in-situ surfactant production (saponification process) on the 1-decyl-3-methyl imidazolium chloride ([C10mim][Cl]) and [C10mim][TfO] adsorption reduction from 3.67 to 2.33 and 4.21 to 3.34 mg IL/g rock, respectively. The performed core flooding experiments using the optimum chemical formulation showed the possibility of tertiary oil recovery with maximum oil recovery of 28.8% based on original oil in place in the presence of 500 ppm.

The bile salt/phospholipid ratio determines the extent of in vitro intestinal lipolysis of triglycerides: Interfacial and emulsion studies

This study focused on the protein-stabilised triglyceride (TG)/water interfaces and oil-in-water emulsions, and explored the influence of varying molar ratios of bile salts (BSs) and phospholipids (PLs) on the intestinal lipolysis of TGs. The presence of these two major groups of biosurfactants delivered with human bile to the physiological environment of intestinal digestion was replicated in our experiments by using mixtures of individual BSs and PLs under in vitro small intestinal lipolysis conditions. Conducted initially, retrospective analysis of available scientific literature revealed that an average molar ratio of 9:4 for BSs to PLs (BS/PL) can be considered physiological in the postprandial adult human small intestine. Our experimental data showed that combining BSs and PLs synergistically enhanced interfacial activity, substantially reducing oil–water interfacial tension (IFT) during interfacial lipolysis experiments with pancreatic lipase, especially at the BS/PL–9:4 ratio. Other BS/PL molar proportions (BS/PL–6.5:6.5 and BS/PL–4:9) and an equimolar amount of BSs (BS–13) followed in IFT reduction efficiency, while using PLs alone as biosurfactants was the least efficient. In the following emulsion lipolysis experiments, BS/PL–9:4 outperformed other BS/PL mixtures in terms of enhancing the TG digestion extent. The degree of TG conversion and the desorption efficiency of interfacial material post-lipolysis correlated directly with the BS/PL ratio, decreasing as the PL proportion increased. In conclusion, this study highlights the crucial role of biliary PLs, alongside BSs, in replicating the physiological function of bile in intestinal lipolysis of emulsified TGs. Our results showed different contributions of PLs and BSs to lipolysis, strongly suggesting that any future in vitro studies aiming to simulate the human digestion conditions should take into account the impact of biliary PLs – not just BSs – to accurately mimic the physiological role of bile in intestinal lipolysis. This is particularly crucial given the fact that existing in vitro digestion protocols typically focus solely on applying specific concentrations and/or compositions of BSs to simulate the action of human bile during intestinal digestion, while overlooking the presence and concentration of biliary PLs under physiological gut conditions.

Formulation and Characterization of Soybean Oil-in-Water Emulsions Stabilized Using Gelatinized Starch Dispersions from Plant Sources.

Consumers are concerned about employing green processing technologies and natural ingredients in different manufacturing sectors to achieve a "clean label" standard for products and minimize the hazardous impact of chemical ingredients on human health and the environment. In this study, we investigated the effects of gelatinized starch dispersions (GSDs) prepared from six plant sources (indica and japonica rice, wheat, corn, potatoes, and sweet potatoes) on the formulation and stability of oil-in-water (O/W) emulsions. The effect of gelatinization temperature and time conditions of 85-90 °C for 20 min on the interfacial tension of the two phases was observed. Emulsification was performed using a primary homogenization condition of 10,000 rpm for 5 min, followed by high-pressure homogenization at 100 MPa for five cycles. The effects of higher oil weight fractions (15-25% w/w) and storage stability at different temperatures for four weeks were also evaluated. The interfacial tension of all starch GSDs with soybean oil decreased compared with the interfacial tension between soybean oil and water as a control. The largest interfacial tension reduction was observed for the GSD from indica rice. Microstructural analysis indicated that the GSDs stabilized the O/W emulsion by coating oil droplets. Emulsions formulated using a GSD from indica rice were stable during four weeks of storage with a volume mean diameter (d4,3) of ~1 µm, minimal viscosity change, and a negative ζ-potential.

Interfacial assembly and properties of amphiphilic polymer-grafted nanoparticles: Effect of chemical design and density of grafted polymers

Despite extensive research conducted on the polymer-grafted nanoparticle (PGNP) systems for the development of emulsifiers with enhanced performance, little is known about the effects of the grafting architecture and density on the interfacial assembly and interfacial tension reduction behavior of the oil/water (O/W) interface at the molecular level. We performed coarse-grained molecular simulations of both biphasic and emulsion droplet systems with emulsifiers, including Janus (grafting of hydrophilic (HI) and hydrophobic (HO) homopolymers onto two regions of the surface), HI–HO (grafting of diblock polymers with HI monomers as inner blocks and HO monomers as outer blocks), and HO–HI PGNPs, for various graft densities and volume fractions of PGNPs. Compared with the diblock PGNPs, the grafted HI and HO homopolymers of Janus PGNPs penetrate the oil or water phase, rather than assembling at the O/W interface. The depletion of the interface of grafted polymers increases the interfacial tension; consequently, the Janus PGNPs are not effective in reducing the interfacial tension for all the investigated graft densities. The interfacial assembly behavior of the HI–HO and HO–HI PGNPs, whose insoluble blocks have asymmetric interactions with the O/W phases, depends on the graft density and volume fraction. This is particularly the case for their dispersibility, which is an important factor for the interfacial tension. At low graft density, we observe a uniform distribution of HO–HI PGNPs at the O/W interface, resulting in an effective reduction in interfacial tension. At high volume fractions of PGNPs with high graft density, a more tightly packed distribution is observed between HO–HI PGNPs than between HI–HO PGNPs, and their changes in assembly behavior reverse the rate of decrease in the interfacial tension of HO–HI and HI–HO PGNPs. Our results indicate that the grafting architectures of diblock polymers have a significant influence on the assembly behavior at the interface and interfacial tension, and that the appropriate grafting architecture for effective emulsifiers that stabilize the interfaces is different depending on the graft density and volume fraction of the PGNPs. This study also provides new insights into the relation between the interfacial assembly and the stability of emulsion droplets covered by the PGNPs. We observe that the diblock PGNPs, which have the insoluble block as the inner block, are more promising candidates for stabilizing emulsions compared with Janus PGNPs. In the opposite case, the insoluble blocks become the “sticky” points for the adhesion of emulsion droplets, resulting in droplet–droplet coalescence even for effective emulsifiers in reducing interfacial tension. The findings of this study offer a theoretical guide for designing optimal PGNPs for specific volume fractions and optimal graft densities and volume fractions for the grafting architectures of synthesizable PGNPs, and they support the progression from the trial-and-error empirical approaches for developing improved emulsifiers.

Pore scale investigation of chelating agents flooding for enhanced oil recovery

Recently, laboratory tests have shown a positive response to chelating agent brines in sandstone and carbonate reservoirs as a new enhanced oil recovery technique. There is little research on direct and visual evidence of underlying mechanisms behind the chelating agent effects. In this study, a microfluidic method was established using glass micromodel to investigate the micro-mechanisms of displacement under ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) chelating agent at the pore-scale level. Furthermore, for the study of fluid/fluid interactions, EDTA brine and DTPA brine were brought into contact with two different crude oils to examine the possible compositional changes. For this purpose, sample tests, Fourier Transform Infrared Spectroscopy (FTIR), microscopic image analysis, and dynamic interfacial tension (IFT) measurements were conducted. The FTIR data showed EDTA brine and DTPA brine induced changes in the oil sample composition compared to seawater, which can be related to the formation of water-in-oil micro-dispersions. Microscopic image analysis on samples confirmed the formation of these micro-dispersions. The visual study by the micromodel demonstrated the micro-dispersion formation in the tertiary injection of EDTA and DTPA brine. Based on the observation made, the pore-scale mechanisms of chelating agent flooding involve the chelating agent brine penetrating the crude oil, resulting in micro-dispersion formation. These micro-dispersions tend to alter wettability to a more water-wet state, facilitate oil detachment from the surface, redistribution of oil saturation, and thus leading to improved oil recovery. The observed IFT reduction aids the penetration of EDTA and DTPA brine into the crude oil to form micro-dispersions.

Molecular dynamics insights into gas-water interfacial tension: Optimizing hydrogen storage in subsurface conditions

This study presents a comprehensive analysis of interfacial tension (IFT) between pore water and hydrogen-cushion gas mixtures in subsurface porous media, a key variable in the distribution of gas mixtures for hydrogen storage. Employing molecular dynamics simulations, we developed two IFT models at 20 MPa and 373 K: one for an H2–CO2–H2O system and another for an H2–CH4–H2O system. The models reveal that increasing cushion gas concentration reduces gas-water IFT. Notably, for H2–CO2–H2O mixtures, the IFT substantially decreases with CO2 concentration up to 40%, after which the reduction rate diminishes. In H2–CH4–H2O mixtures, the IFT decreases linearly with CH4 concentration. The study attributes these variations to local density distributions and molecular orientation effects. Specifically, CO2 adsorption at the interface up to 40% concentration significantly lowers IFT, while CH4 adsorption proportionally decreases IFT. The influence of CO2 on water molecule orientation at the interface, in contrast to the non-effect of CH4, is also critical in enhancing IFT reduction. Our results also highlight the reduction of H2 self-diffusion at the interface caused by CO2 and CH4, an essential factor in optimizing subsurface hydrogen storage operations.

Unraveling the Impact of Ethylenediaminetetraacetic Acid Chelating Agents on the Oil Recovery Processes: An Insight into Its Role in Fluid-Fluid and Rock-Fluid Interactions.

In recent years, chelating agents have garnered increasing attention due to their unique capabilities in addressing challenges associated with chemically enhanced oil recovery materials. Most previous studies have primarily focused on examining the influence of chelating agents on rock-fluid interactions. However, their effects on fluid-fluid interactions, specifically on interfacial tension (IFT) characteristics under various conditions, remain relatively unknown. This study investigates the effect of crucial reservoir parameters on the performance of ethylenediaminetetraacetic acid (EDTA) chelating agents in the IFT between crude oil and brine. Furthermore, the study evaluated the impact of varying concentrations of this agent on rock wettability alteration, zeta potential, and spontaneous imbibition. The results illustrated that introducing EDTA at high concentration into seawater (SW) solution reduced the IFT by 85%. Additionally, while higher pH levels contributed to IFT reduction due to increased hydroxyl ions, excessive salinity levels resulted in elevated IFT. Raising the temperature from 30 to 75 °C further decreased the IFT, changing the IFT for optimal EDTA concentration from 20.43 to 2.56 mN/m (∼88% reduction). The changes in zeta potential and contact angle measurements indicated that solutions of 5 and 7 wt % EDTA shifted rock wettability from oil-wet to strongly water-wet, resulting in the wettability alteration index of 1.01 and 1.02, respectively. Inductively coupled plasma analysis, on the other hand, revealed substantial chelation of metal ions from both the solution and rock when EDTA was added to the rock/SW system. This resulted in a significant increase in Ca2+ ions and a decrease in Mg2+ ions, attributed to the multi-ion exchange phenomenon.

Mutual role of dodecylbenzene sulfonic acid on enhanced oil recovery and asphaltene inhibition in low salinity medium: Experimental and XDLVO study

Understanding the molecular interactions during oil recovery processes can shed light on screening new chemicals for future operations. Of particular interest are chemicals capable of providing the mutual role of asphaltene inhibition and interfacial tension reduction at liquid–liquid and rock-liquid interfaces. This study delves into the interfacial interactions between low-salinity brines, model oils containing dodecylbenzene sulfonic acid, and dolomite rock surfaces. In the experimental part, the asphaltene precipitation inhibition efficacy of dodecylbenzene sulfonic acid was evaluated through filtration and precipitation test, and its oil recovery performance was examined from interfacial tension reduction and wettability alteration viewpoints. The theoretical part was then followed by the implementation of the surface energy concept based on the XDLVO theory, where acid-base and Lifshitz-van der Waals interaction energies, as well as the work of cohesion/adhesion between interacting bodies in asphaltene and oil recovery systems, were considered. The results obtained from this study revealed that dodecylbenzene sulfonic acid, owing to its acidic nature and the long alkyl chain in its structure, could simultaneously perform the role of asphaltene inhibitor and oil recovery agents. In particular, asphaltene particles showed less tendency to aggregate and form macrostructures in the presence of low-salinity brines formulated with magnesium chloride. The total interaction energy between asphaltene particles was almost halved by the addition of dodecylbenzene sulfonic acid. The low interfacial tension of 0.16 mN/m between model oil containing 1 wt% of DBSA and low-salinity brine containing 5000 mg/L magnesium chloride and the wettability alteration of the dolomite sample toward water-wetness were also confirmed by theoretical calculations using the concept of work of adhesion.

Analysis of metallurgical defects in enamel steel castings

Abstract The relevant experiments and studies were conducted to address the metallurgical defects such as subcutaneous bubbles and slag inclusions occurring during the enamel steel continuous casting process. According to the high-temperature experimental results, calculations were made to determine the changes in viscosity and tension due to the steel reaction with the slag. Based on the experimental findings, there was a notable variation in the content of SiO2 and Al2O3 in the slag before and after the reaction. The concentration of the element Al in the steel melt significantly decreased, whereas the concentration of Ti showed a minimal change. These observations indicate that the reduction of SiO2 at the slag–steel interface is predominantly attributed to the role of Al. The calculation results showed that at 300 s of reaction time, the viscosity rapidly increased from 0.108 to 0.133 Pa·s and then slowly increased to 0.155 Pa·s; The interfacial tension rapidly decreased from its initial value of 1,380 mJ·m−2 to a minimum of 1,320 mJ·m−2, and it then slowly increased to an equilibrium state. Therefore, the main cause of the occurrence of porosity defects in the enamel steel continuous casting process is the reduction of interfacial tension between slag, steel, and gas caused by the reaction between the slag and steel, as well as the foaming of the slag.

Interfacial Behaviors and Oil Detachment Mechanisms by Modified Silica Nanoparticles: Insights from Molecular Simulations.

Surfactant flooding has been considered as a promising approach for chemically enhanced oil recovery (EOR). However, this technique encounters several limitations, such as high costs, environmental concerns, and reduced efficiency under high-temperature and high-salinity reservoir conditions. Recently, nanoparticles have also been proposed as an alternative for EOR due to their superior properties compared with surfactants. This research employs molecular dynamics simulations to explore the impact of modified SiO2 nanoparticles on oil-water interfacial behaviors and the detachment of oil droplets from an oil-wet surface. The simulation results reveal that modified nanoparticles, featuring hydrophilic and hydrophobic functional groups, have slight impacts on interfacial tension reduction of the oil-water interface. Nanoparticles with varying degrees of modification exhibit distinct positions within the interface, consequently influencing the thickness of the interfacial layer. Notably, the interactions among the nanoparticles, oil molecules, and surface facilitate the formation of a water channel, thereby enhancing the process of oil detachment. Comparative analysis indicates that in terms of oil displacement efficiency, the thickness of the interfacial layer has a more significant impact than interfacial tension reduction. Furthermore, to elucidate the mechanisms of modified nanoparticles enhancing the oil recovery rate, the interaction energies among the oil droplet, nanoparticles, water, and surface are analyzed. The molecular-level insights derived from this investigation could provide valuable guidance for the design of modified nanoparticles tailored to EOR applications.

Stabilizing effect of silver carp myofibrillar protein modified by high intensity ultrasound on high internal phase emulsions: Protein denaturation, interfacial adsorption and reconfiguration

This study evaluated the impact of high intensity ultrasound (HIU) on myofibrillar proteins (MP) from silver carp, and investigated the stabilizing effect of HIU-treated MP (UMP) on high internal phase emulsions (HIPEs). Ultrasonic cavitation induced protein denaturation by decreasing size and unfolding conformation, to expose more hydrophobic groups, particularly UMP at 390 W, showing the smallest particle size (181.71 nm) and most uniform distribution. These structural changes caused that UMP under 390 W exhibited the highest surface hydrophobicity, solubility (92.72 %) and emulsibility (115.98 m2/g and 70.4 min), all of which contributed to fabricating stable HIPEs with oil volume fraction up to 0.8. UMP-based HIPEs possessed tightly packed gel network and self-supporting appearance due to the adsorption of numerous proteins at the oil-water interface and the reduction of interfacial tension by protein reconfiguration. The larger interface coverage reinforced cross-linking between interfacial proteins, thus increasing the viscoelasticity and recoverability of HIPEs, also the resistance to centrifugal force, high temperature (90 °C, 30 min) and freeze-thaw cycles. These findings furnished insightful perspectives for MP deep processing through HIU, expanding the high-value application of UMP-based HIPEs in fat replacer, nutritional delivery system with high encapsulation content and novel 3D printing ink.

Forecasting the Problem of Excessive Oil Entrainment in a Desalter Using Spinning Drop Method.

Frequent desalter upsets in the refineries processing opportunity crude oils are often triggered by a rapid and uncontrollable buildup of the rag layer, a thick water-in-oil emulsion, at the oil-brine interface. This is caused by spontaneous emulsification of brine in oil. This study investigates a unique observation from a spinning drop (SD) tensiometer, revealing the low apparent interfacial tension and rigidity of SD caused by spontaneous emulsification. Fine droplets of brine generated through spontaneous emulsification decorate the SD surface and form a stable, low-energy bilayer. Simulated rag layers using the brines from upset incidences exhibit similar behavior, indicating that spontaneous emulsification is driven by chemical species in brine, which promote osmotic water transport. The rate of rag layer buildup correlates with the rate of spontaneous emulsification, with the temperature coefficient of interfacial tension reduction serving as a sensitive indicator. An imminent upset in the operation can be forecasted by measuring this temperature coefficient, enabling preventive measures.

Impact of cationic surfactant-coated hydrophilic nanoparticles on polymeric solution performance in chemical enhanced oil recovery (CEOR) from a two-dimensional porous medium

This study aims to investigate the mechanisms underlying enhanced oil recovery (EOR) through chemical injection and explore the key parameters influencing these mechanisms in a two-dimensional porous medium. Distilled water, polyacrylamide (PAM), α-Al2O3 nanoparticles, and cetyltrimethylammonium bromide (CTAB) surfactant were employed for this purpose. The effects of interfacial tension (IFT), viscosity, and zeta potential measurement were also examined. The results revealed that the injection of PAM polymer increased the viscosity of the displacing fluid, and enhanced the sweep efficiency. This resulted in a 35 % increase in the oil recovery factor compared to the water injection alone. Furthermore, the introduction of alumina (α-Al2O3) nanoparticles altered the wettability and stabilized the emulsion, leading to a further increase in the oil recovery factor. In the optimal state, the oil recovery factor reached 63.2 %. Moreover, the study of various concentrations of polymer and nanoparticles illustrated that low concentrations of polymer and high concentrations of nanoparticles in the base fluid resulted in higher oil recovery factors. Furthermore, adding CTAB surfactant ended a significant reduction in IFT, with a decrease from 45.03 to 10.33 mN/m. This reduction resulted in the highest oil recovery factor of 69 %. Consequently, the highest oil recovery factor was achieved using PAM polymer at a concentration of 500 ppm, α-Al2O3 nanoparticles at a concentration of 0.1 wt%, and CTAB surfactant at a critical micelle concentration of 1 mM in the base fluid (pure water), with a constant injection flowrate of 0.1 ml/min.

Biphasic interfacial functioning improvement using naturally derived Hop and Dill surfactants in carbonate reservoirs

This study mainly focuses on the application of environmentally friendly surfactants in enhanced oil recovery (EOR). Two natural and environmentally friendly surfactants of Hop and Dill were introduced to observe their visions of fluid/fluid/rock interfacial activity of surfactant solutions as ion tuned EOR method. Investigations of interfacial tension (IFT) reduction and wettability alteration toward a water-wetting tendency were conducted to evaluate the improvement of oil recovery factor. Dynamic displacement tests of carbonate porous medium flooding including both secondary and tertiary flooding were conducted to observe the validity of IFT reduction and wettability alteration (contact angle decrease, CA) effects. IFT measurements showed that Dill and Hop surfactants can reduce the initial IFT of 28 mN/m to 2.443 and 5.614 mN/m, respectively. Ion concentration tuning showed that 10,000 ppm of NaCl is the optimum concentration that could enhance the optimization value of Dill surfactant from 91.27% to 92.8% (with 17.46% improvement compared with CMC of Dill). In addition, NaCl salt at the same concentration improved the effectiveness of Hop surfactant by 6.1%. Meanwhile, the used surfactants reduced the contact angle from 151° to 75° and 65° for Dill and HOP, respectively. Ion tuning showed that 10,000 ppm of salinity effect could enhance the optimization by Dill and Hop to 70.86 and 71.54%, respectively. Zeta potential measurements proved that the contact angle results in a complementary manner. Core flood tests validated previous results through the improvements in the recovery of oil by 8.56 and 10.11% original oil in place (OOIP) for HOP and Dill natural surfactants, respectively.

Insights into Molecular Dynamics and Oil Extraction Behavior of the Polymeric Surfactant in a Multilayered Heterogeneous Reservoir.

Interlayer heterogeneity, an inevitable and complex challenge during water flooding, seriously constrains the spread of the sweep region and oil recovery enhancement in multilayered heterogeneous reservoirs. To overcome this challenge, a novel polymeric surfactant, having an excellent performance in the reduction of interfacial tension (IFT) and the increase of viscosity of displacing fluid, is applied for enlarging the sweep resonance and increasing the oil washing efficiency. Through the molecular dynamics (MD) simulation, the molecular distributing mechanisms of the polymeric surfactant at the oil-water interface are analyzed to provide the theoretical basis for explaining the microscopic mechanism of oil extraction. To directly reflect the microscopic behavior of oil extraction, multiple transparent sand-packed models are designed to investigate the flowing behavior of different fluids and the extracted mechanisms of the remaining oil in both pore and macroscales. The multilayered heterogeneous reservoirs consisting of high-, moderate-, and low-permeability layers are fabricated to represent a heterogeneous characteristic. The recognition from the visual experiment and MD simulation can study the performance control, the extracting performance of the remaining oil, and the expression of the displacing front from different perspectives. The results from MD simulation demonstrate that the polymeric surfactant can promote the disintegration of the remaining oil and enhance its mobility. The experimental results indicate that the sweep efficiency is restricted by viscous fingering and tongue advance. Through the analysis of mathematical models, the rising mobility ratio and the location of the displacing front have a strong positive relationship with viscous fingering and tongue advance, which can reasonably explain the plugging performance of the polymeric surfactant, greatly improving the sweeping effect of the whole reservoir. Moreover, the Marangoni effect generated by the IFT gradient can induce the transformation of interfacial energy to displacement kinetic energy by the emulsification of the oil-water interface so that the remaining oil in the blind-end pore can be effectively extracted. However, by comparing data from image quantification techniques and production dynamic performance, the sweep efficiency (484%) was significantly greater than that of oil recovery (300%), demonstrating that the expanded sweep effect still plays a dominant role in the extraction of remaining oil after polymeric surfactant flooding. This study provides a novel plugging and effective washing agent that is expected to be an excellent and comprehensive method for solving the problem of low oil recovery in multilayered heterogeneous reservoirs.