ROLES OF CO-SURFACTANT AND CO-SOLVENT IN SURFACTANT WATERFLOODING

Residual oil displacement and surfactant retention were measured in Berea cores with well-characterized surfactant systems; phase and interfacial tension behavior was determined as well. The results, interpreted in terms of what is known about the different surfactant-rich microstructures present in aqueous sodium 4-(l'-heptylnonyl) benzenesulfonate (SHBS) alone or in conjunction with the co-surfactant sodium dodecylsulfate (SDS) or the co-solvent n-butanol (NBA), indicate that the large retention by Berea rock of liquid crystalline dispersions can be greatly reduced by sonicating them to produce tiny vesicles or by adding a suitable co-solvent or co-surfactant to dissolve the liquid crystallites.

The core tests show that high oil recovery with low retention can be achieved by injecting isotropic solutions of alcohol-solubilized surfactant or ultradispersions of vesicles, although the former performed better than the latter. These are able to form, in situ upon contact with residual oil, a surfactant-rich third phase with low interfacial tensions against both aqueous and oleic phases so that it can mobilize the oil.     

A study of surfactant flooding at high salinity and hardness

The main purpose of this work was to evaluate surfactant systems in terms of viscosities and retention levels in Berea sandstone and in terms of their oil displacement efficiencies. Commercially available surfactants can act as effective cosurfactants to petroleum sulfonates in high salinity and high hardness environments. Such systems can achieve the ultralow interfacial tensions required for effective tertiary oil recovery. The two cosurfactants producing effective systems distribute between the phases in such a way that one is between the upper and middle phases, and the other is between the middle and lower phases. The cosurfactant material increases the excess phase uptake into the microemulsion-rich phase which is opposite to the behavior of alcohols used in low salinity formulations. Tertiary oil in Berea sandstone is recoverable by such surfactant systems in high salinity and high hardness environments. The chromatographic separation of surfactant species has been observed. Retention levels are quite high and must be reduced substantially before these systems can be commercialized.     

Preparation and characterization of monoclinic sulfur nanoparticles by water-in-oil microemulsions technique

Nanosized monoclinic sulfur particles have been successfully prepared via the chemical reaction between sodium polysulfide and hydrochloric acid in a reverse microemulsions system, with theolin, butanol, and a mixture of Span80 and Tween80 (weight ratio 8 : 1) as the oil phase, co-surfactant and surfactant, respectively. Transparent microemulsions were obtained by mixing the oil phase, surfactant, co-surfactant, and the aqueous phase in appropriate proportion using an emulsification machine at the room temperature. The resulting sulfur nanoparticles were characterized by dynamic light scattering (DLS), X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM).     

Extraction of anionic dyes with ionic liquid–nonionic surfactant aqueous two-phase system

The cloud point of nonionic surfactant (Triton X-114) in ionic liquid ([Bmim]Cl) aqueous solution exhibits as increase and then decrease and increase again with the increase of ionic liquid (IL) content, which is the origin of an IL–nonionic surfactant aqueous two-phase system. The nonionic surfactant-rich phase coexists with a high content of IL aqueous solution phase in the IL–nonionic surfactant aqueous two-phase system. The partitioning of various ionic dyes indicates that anionic species exhibit a high partitioning coefficient between the IL-rich phase and the nonionic surfactant-rich phase.     

预分散溶剂萃取平衡与传质特性

预分散溶剂萃取(predispersed solvent extraction,简称PDSE）是一种新型的液-液萃取方法.该过程首先将溶剂制成胶质液体泡沫(colloidal liquid aphron ,简称CLA),同时借助胶质气体泡沫(colloidal gas aphron,简称CGA)实现溶质的分离.本文以磷酸三丁酯（TBP）-煤油为溶剂,以十二烷基苯磺酸钠（SDBS）为水相表面活性剂,以TWEEN 80为油相表面活性剂制备了胶质液体泡沫（CLA）. 用十六烷基三甲基溴化胺（HTAB）为水相表面活性剂制备了胶质气体泡沫（CGA）. 利用半间歇式PDSE过程萃取苯酚溶液.研究了pH值、表面活性剂浓度、相比等对萃取率和平衡分配系数的影响.实验发现,PDSE过程更适用于小相比（油相∶水相为1∶1000或更小）和极稀溶液的萃取.实验还发现, PDSE过程的萃取率随着CLA中TBP浓度的增加而增加, 随相比的增加而提高.利用刚性球模型计算了CLA的传质系数,并与传统的液滴进行了比较.在相同的粒径下,CLA比传统的液滴具有更高的分散相总传质系数;与传统萃取塔中存在的液滴相比,CLA也具有一定的优势.此外,对于两者K_da的比较,更体现了CLA的优越性.     

Aqueous Extended-Surfactant Based Method for Vegetable Oil Extraction: Proof of Concept

The use of hexane to extract vegetable oil from oilseeds is of growing concern due to hexane’s environmental impact and because of worker exposure concerns. The goal of our work is to demonstrate that the aqueous extended-surfactant-based method is a viable alternative for vegetable oil extraction. In our method, ground oilseeds were dispersed in the aqueous surfactant solution, allowing the oil to be liberated from the seeds as a separate phase from the aqueous phase. The impact of pH, shaking intensity, shaking time and seed to liquid ratio on oil yield are presented. Extended-surfactants are a new type of surfactant with propoxylate (PO) and/or ethoxylate (EO) groups inserted between the hydrophilic head and the hydrophobic alkyl chain of the surfactant molecule. This unique structure of extended-surfactants enables them to produce ultralow interfacial tension with vegetable oils. We have found that at low aqueous concentrations (less than 0.3 wt%), extended-surfactant solutions are able to produce ultralow interfacial tension between aqueous extraction and vegetable oil phases. At optimum condition (seed to liquid ratio of 1–5, 30 min extraction at 150 shakes/min and 30 min centrifugation at 2,170×g) we achieved 93–95% extraction efficiency for peanut and canola oils at 25 °C. The oil quality produced from the aqueous extended-surfactant-based method was found to be comparable or even superior to that obtained from hexane-based extraction, further demonstrating the viability of aqueous extended-surfactant based extraction.     

Acidic Heavy Oil Recovery Using a New Formulated Surfactant Accompanying Alkali–Polymer in High Salinity Brines

The strength of a newly formulated surfactant with an alkali and polymer (AS/ASP) to improve an acidic heavy oil recovery was laboratory evaluated by various flooding experiments. The comparative role of the parameters like chemical nature, surface wettability, salinity, temperature and injection scheme were explored at high temperature and pressure on Berea sandstone rocks. According to the results the anionic surfactant is capable of providing proper oil displacement under high salinity conditions around 15 wt%. Continuous monitoring of differential pressure response and effluents’ state clearly represented the formation of an emulsified oil in high saline solutions with both alkali and surfactant. Adding sodium metaborate to the surfactant solution reduced the interfacial tension (IFT) to ultra low values and decreased the surfactant emulsion generation capability at higher salinities. Besides, adding Flopaam AN113SH to the chemical slug increased the residual oil removal owing to lower mobility ratios. So, while high capillary number and an emulsion phase were generated by the A/S slug phases, adding polymer could further enhance the performance of these chemicals. On the other hand, chemical flooding through the oil-wet medium resulted in shorter break through time, lower differential pressure, finer emulsion formation, and lower oil recovery in comparison to the similar water-wet cases.     

预分散溶剂萃取分离苯酚溶液的研究

Predispersed solvent extraction (PDSE) is a new method for separating solutes from aqueous solution by solvent extraction and one which has shown promise for extraction from extremely dilute solution very efficient and very quick. The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interracial mass transfer and low interfacial mass transfer areas in solvent extraction process. In present paper, colloidal liquid aphrons are successfully generated using kerosene as a solvent,tributyl phosphate(TBP) as an extractant, sodium dodecyl benzene sulphate(SDBS) as surfactant in aqueous phase and Tween-80 in oil phase. Extraction of phenol from dilute solution was studied by using colloidal liquid aphrons and colloidal gas aphrons in a semi-batch extraction column. It has been found that the PDSE process is more suitable for extraction of dilute solutions. It has also been discovered that the PDSE process has a great advantage over traditional single-stage extraction process.     

相分离法制备相变材料微胶囊

相分离法是一种较为简便的微结构聚合物制备方法,通过改变表面活性刺的种类、浓度和聚合物的种类等,可以方便地控制所制备聚合物微球的形貌.研究采用聚甲基丙烯酸甲酯(PMMA)与聚苯乙烯(PS),油相使用的是相变材料十六烷(HD),共溶剂使用的是二氯甲烷(DCM)或三氯甲烷(TCM),将聚合物溶于油相中,通过溶剂挥发导致的相分离作用,以及在界面张力的调控作用下,可以制得多种形貌的微胶囊.     

Interfacial Rheology Measured with a Spinning Drop Interfacial Rheometer: Particularities in More Realistic Surfactant–Oil–Water Systems Close to Optimum Formulation at HLDN = 0

Three different cases were selected to study the effect of physicochemical formulation on interfacial rheology properties of surfactant–oil–water (SOW) systems by increasing the complexity of the system from a basic case. This was performed by changing the normalized hydrophilic–lipophilic deviation (HLD_N) to attain the optimum formulation at HLD_N = 0. Two types of SOW systems were studied: the first one used an ionic surfactant with a salinity scan, and the second one a mixture of two nonionic surfactants in a formulation scan produced by changing their proportion. Both of them contained cyclohexane as a pure oil phase, without alcohol. Sec-butanol was then added as a co-surfactant with hardly any formulation influence on HLD_N. The complexity in interfacial rheology was then increased by changing the oil to a light crude with low asphaltene content. The interfacial rheology is also reported for a realistic system with a high asphaltene content comprised of crude oil diluted in cyclohexane with a conventional surfactant and a commercial demulsifier. The findings confirm that at optimum formulation and whatever the scanning variable (salinity, average ethylene oxide number in the nonionic surfactant mixture, or surfactant/demulsifier concentration), the interfacial tension, and interfacial elastic moduli E, E′, and E″ exhibit a deep minimum. These observations are related to the acceleration of the surfactant exchanges between the interface, oil, and water, near the optimum formulation. Several arguments are put forward to explain how these findings could contribute to the decrease in emulsion stability at HLD_N = 0.     

辛基酚聚氧乙烯醚烷基磺酸钠溶液的性能研究

对非离子-阴离子型表面活性剂辛基酚聚氧乙烯醚(10)烷基磺酸钠(OPS-10)的溶液性能进行了研究。用表面张力法测定OPS-10的CMC为65 mg/L;在85℃、无机盐离子浓度90 000 mg/L的水溶液中,OPS-10表现出了良好的抗温抗盐性;动态界面张力研究显示,OPS-10降低油-水动态界面张力的曲线呈"L"型,平衡值达到10-2数量级;室内驱替实验表明,对于特低渗透率的岩心,OPS-10可以在水驱的基础上提高驱油效率2.89%,优于十二烷基苯磺酸钠的驱替效果。基于在上述方面表现的良好性能,OPS-10可以作为驱油剂或助剂进行高矿化度水和高温油藏的驱油实验研究和应用。     

聚合物-表面活性剂对油/水界面剪切粘度的影响

利用正交实验设计研究了聚合物A、石油磺酸盐B、表面活性剂C三种因素共存时对原油模拟油/水界面剪切粘度的影响。单因素实验表明,表面活性剂C使原油模拟油/水界面粘度降低,而聚合物A的存在则使油/水界面剪切粘度上升。而三种因素共存时,在实验条件下,表面活性剂C对油/水界面剪切粘度有一定的影响,聚合物A和石油磺酸盐B看不出有较大影响。因此,在聚合物-表面活性剂复合驱体系中,界面剪切粘度的变化主要取决于体系中表面活性剂的变化。     

Influence of phase orientation on dynamic interfacial tension measured by drop volume tensiometry

In processes involving two liquid phases, such as enhanced oil recovery, one phase is often present in a drop form (drop phase) while the other is in continuous form (bulk phase). In the present paper, the effect of such phase orientation on dynamic interfacial tension between the two phases formed by the partially miscible system composed of butanol-1 and water has been investigated by using the method of drop volume tensiometry. With butanol-rich (butanol-1 saturated by water) as the drop phase and water-rich (water saturated by butanol-1) as the bulk phase, the interfacial tension is 1.70 ± 0.02 mN/m. The interfacial tension for water-rich as the drop phase is almost identical at 1.72 ± 0.03 mN/m. Addition of a surfactant, sodium dodecyl sulfate, to the system has been studied. When the surfactant is added to the drop phase (either butanol-rich or water-rich), the magnitude of the decrease in interfacial tension is smaller than when surfactant is added to the bulk phase (water-rich or butanol-rich) or to both phases. Under otherwise identical conditions, when the water-rich acts as the drop phase, the apparent interfacial tension is higher than that when the butanol-rich acts as the drop phase.     

Effect of salinity and alcohol partitioning on phase behavior and oil displacement efficiency in surfactant-polymer flooding

The equivalent alkane carbon number (EACN) of a crude oil, namely Ankleshwar crude, is successfully modeled by a mixture of pure alkanes. The EACN of the crude oil is found to be 9.3, and an appropriate mixture of nonane and decane exhibited phase behavior similar to that of the crude oil. A surfactant system for a water flooded reservoir at 80 C and having a salinity in the range of 2% to 3% NaCl is formulated by blending a phosphated ester with a petroleum sulfonate in the weight ratio of 2/5. The addition of phosphate ester not only increases the salt tolerance of the petroleum sulfonate system, it also broadens the IFT minimum. The oil displacement tests at 80 C in sandpacks and Berea cores showed that the surfactant formulation containing tertiary amyl alcohol (TAA) displaced 92% oil in sandpacks and 79% crude oil in Berea cores. The oil recovery efficiency was poor when formulations contained other alcohols. From the effluent surfactant concentration, it is shown that there is a correlation between the tertiary oil recovery, surfactant breakthrough and surfactant retention in porous media. It is proposed that, because alcohols such as isopropyl alcohol (IPA), isobutyl alcohol (IBA) and secondary butyl alcohol (SBA) partition significantly in the equilibrated excess brine phase, the alcohol-depleted surfactant slug forms stable emulsions resulting in faster breakthrough of surfactant in the effluent and lower oil displacement efficiency. In the case of TAA-containing formulation, there is a partitioning of TAA in the oil phase. Therefore, there is a mass transfer of alcohol from surfactant slug to the oil ganglia in porous media. This produces a transient ultralow IFT between residual oil and the surfactant solution which mobilizes oil, resulting in higher oil displacement efficiency. Presented in part at International Symposium on Oilfield and Geothermal Chemistry, June 1983, in Denver, CO.     

Ultralow oil-water IFTs using neutralized oxidized hydrocarbons as surfactants

Surfactants that may be suitable for application in enhanced oil recovery have been produced from C₂₂ and C₂₆ paraffinic and naphthenic petroleum fractions by a two-step process. The hydrocarbon feed stocks were first oxidized in the vapor-phase, followed by neutralization of the oxidized products with aqueous alkali. As a result, dilute solutions of organic acid salts were produced that achieved ultralow (<10⁻² dyne/cm) interfacial tensions against a synthetic oil. Surfactant solutions that exhibited the lowest interfacial tensions (IFTs) were prepared from neutralizations that used low concentrations of sodium hydroxide rather than sodium silicate, sodium tripolyphosphate, or sodium carbonate. Neutralizations that used sodium silicate or sodium carbonate resulted in surfactant solutions having IFT profiles that were less sensitive to the electrolyte concentration. When sodium hydroxide was combined with either sodium silicate or sodium tripolyphosphate in the neutralizations, solutions having intermediate IFT properties were produced. The amount of alkali used in the neutralizations was observed to affect the IFT properties of the resultant surfactant solution. The electrolyte concentration at which the minimum IFT occurred was inversely related to the pH of the surfactant solution. For surfactant solutions of common pH prepared from different concentrations of oxidized product, the minimum IFTs all occurred at the same concentration of electrolyte. Surfactant solutions remained interfacially active even in the presence of significant concentrations of calcium chloride. One pore volume of a solution containing only about 1% of active surfactant recovered 42.0% of the residual oil in a tertiary core-flood experiment.     

硫酸酯盐双子表面活性剂的合成和界面张力的研究

实验室条件下,以长链羧酸(月桂酸)、聚乙二醇等为主要原料,通过赫尔-乌尔哈-泽林斯基反应等和酯化反应,用醚键加入方式加入联接基团,用浓硫酸加成反应加入硫酸酯键,从而在实验室条件下合成具有特殊结构的双子表面活性剂-GA12-S-12.通过用旋转液滴法测合成的硫酸酯盐阴离子双子表面活性剂的表面张力,测得其临界胶束浓度(CMC)为438 mg/L,临界胶束浓度下表面张力为30.9 mN/m,并对比十二烷基硫酸钠水溶液表面张力,显示GA12-S-12[低聚二醇(α-硫酸酯钠)月桂酸双酯阴离子双子表面活性剂]具有更优的表面活性.进一步配制不同浓度的GA12-S-12表面活性剂溶液,测定它们与长庆五里湾原油的界面张力,效果显示其适用于五里湾区原油采收率的提高.     

双水相胶束萃取苯酚

根据胶束的加溶原理和非离子表面活性剂系统在浊点温度以上自动分相的现象 ,采用TritonX - 10 0胶束系统萃取苯酚 .结果表明 :苯酚的比胶束加溶量与其在水相的平衡浓度成比例关系 .测定了比例系数 ,即加溶平衡常数 .由此建立了数学模型 ,讨论了表面活性剂浓度、溶质浓度、pH值等因素对萃取率的影响 .模型计算结果和实验结果都说明 ,调节pH值可以反萃取苯酚的原因是苯酚电离改变了加溶平衡常数     

Effect of Electrolyte and Temperature on Volatile Organic Compounds Removal from Wastewater Using Aqueous Surfactant Two-Phase System of Cationic and Anionic Surfactant Mixtures

Abstract

Benzene, toluene, ethylbenzene, and xylene are frequently observed contaminants in industrial wastewaters causing concerns about environmental and health effects. An aqueous surfactant two-phase (ASTP) extraction system using mixtures of cationic and anionic surfactants have been shown to be a promising surfactant-based separation technique to concentrate solutes such as proteins and dyes from aqueous solution. A phase separation of a surfactant solution occurs at certain surfactant compositions and concentrations, forming two isotropic phases. One is rich in surfactant aggregates (surfactant-rich phase) and the other is lean in surfactant aggregates (surfactant-dilute phase). Most of the organic contaminants tend to solubilize and concentrate in the surfactant-rich phase, leaving the surfactant-dilute phase containing only small amounts of contaminants as remediated water. The effect of NaCl addition on the critical micelle concentration (CMC) and the extraction ability of ASTP formed by mixtures of cationic surfactant (dodecyltrimethylammonium bromide; DTAB) and anionic surfactant (alkyl diphenyloxide disulfonate; DPDS) at 50 mM total surfactant concentration with a 2:1 molar ratio of DTAB:DPDS was investigated; the CMC of the mixture slightly decreases with increasing NaCl concentration. The extraction and preconcentration of benzene are greatly enhanced by added NaCl. The higher the degree of hydrophobicity of contaminants, the greater the extraction into the surfactant-rich phases. At 1.0 M NaCl addition, about 95% of xylene, 92% of ethylbenzene, 90% of toluene, and 79% of benzene are extracted into the surfactant-rich phase within a single stage extraction and the contaminant partition ratios can be as high as 395 for xylene, 273 for ethylbenzene, 206 for toluene, and 84 for benzene, which are greater than those obtained from the conventional ASTP extraction system using nonionic surfactants.     

Disintegration of granules made from pure nonionic surfactants and surfactant mixtures

Dissolution in water of pure liquid nonionic surfactants and some of their mixtures was studied in previous research in this laboratory. In the work described here, a hanging drop slide was used to study disintegration behavior in water of corresponding granules consisting of many zeolite particles bound together with a liquid nonionic surfactant. Granules disintegrated below the cloud point of the nonionic surfactant or mixture. Few differences in disintegration time were seen for various systems. However, disintegration did not occur when the neat surfactant developed viscous myelinic figures upon contact with water. Nor was it observed when a dilute aqueous phase coexisted with a surfactant-rich L₁ phase or L₃ (sponge) phase at equilibrium.     

Partition behaviour of antioxidative phenolic compounds in heterophasic systems

Differences in the efficiency of antioxidants in dispersed lipid systems may be related to the differential solubility of the antioxidants within the physically distinct phases of colloidal food systems. This study determined the partitioning of antioxidants in water/oil systems, surfactant solutions (dodecyltrimethylammonium bromide, DTABr, sodium dodecylsulfate, SDS, polyoxyethylenesorbitan monolaurate, Tween 20), and emulsions. There were significant differences in the partition of the antioxidants between oil, water and interfacial phases both as a function of pH and surfactant. The proportions of hydrophilic antioxidants (ferulic acid, caffeic acid, gallic acid, propyl gallate, catechin and Trolox) showed significant decreases in the aqueous phase when lowering the pH from 7.0 to 3.0 in Tween 20 emulsions. DTABr lowered the proportion of all antioxidants in the unbuffered aqueous phase to a higher extent than SDS or Tween 20. Changing the ionic strength (5mM NaCl to 50mM NaCl) did not cause significant differences in water/oil systems. Therefore, the effectiveness of hydrophilic antioxidants in heterophasic systems is influenced by their partition into the different phases of water/oil, surfactant and emulsion systems.