Stability of the Oil-water Emulsion Formed During Amphiphilic Polymer Flooding

The amphiphilic polymer can greatly improve the stability of produced liquid and thus makes it difficult to treat. It is of great necessity to study the stability of amphiphilic polymer flooding O/W crude oil emulsion. O/W crude oil emulsion tends to be more stable with increasing amphiphilic polymer concentration and decreasing holding temperature. Amphiphilic polymer flooding O/W crude oil emulsion is much more stable, especially when polymer concentration is above critical aggregation concentration. Aggregation formed by hydrophobic groups of the amphiphilic polymer is beneficial to the stability of amphiphilic polymer flooding O/W crude oil emulsions.     

聚丙烯酰胺影响原油乳状液稳定性的机理

以不同粘均分子量（用紫外光降解制得,相对分子质量分别为：398万、114万、60万、26万）和不同浓度的聚丙烯酰胺溶液作为水相,和原油配制成含聚原油乳状液。通过对原油乳状液脱水率的测定,考察了聚丙烯酰胺的相对分子质量、浓度对原油乳状液稳定性的影响,同时测定了它们的分配系数和粘度,并与通过加NaCl降粘的聚丙烯酰胺溶液对比考察了聚丙烯酰胺影响原油乳状液稳定性的本质。结果表明：当聚丙烯酰胺相对分子质量大于114万时,将明显增强原油乳状液稳定性;当聚丙烯酰胺相对分子质量低于114万时,其对乳状液稳定性无明显影响。影响原油乳状液稳定性的根本因素是聚合物溶液自身的粘度,与分配系数关系不大。聚丙烯酰胺溶液的自身粘度越大,对原油乳状液稳定性的增强作用越明显。     

水解聚丙烯酰胺对原油破乳的影响

采用紫外光降解法制备了4种不同黏均相对分子质量(Mη)的聚合物溶液,并用其配制不同质量浓度的含该聚合物的原油乳液。通过测定原油乳液脱水率、界面张力和分配系数,考察了聚合物质量浓度、黏均相对分子质量及聚合物种类对原油破乳的影响。实验结果表明,聚合物种类及其黏均相对分子质量是影响原油破乳的主要因素。对于水解聚丙烯酰胺(LDHPAM),当Mη1.14×106时,相对于空白样,它对原油乳液稳定性有明显的增强作用;当Mη1.14×106时,它对原油乳液稳定性无明显影响;与LDHPAM相比,疏水缔合聚合物(AP-P4)由于分子中含有少量的疏水基团,更易吸附于油水界面,对原油乳液稳定性的影响较为显著,当AP-P4质量浓度大于等于300mg/L时,原油乳液在55℃下静置2h后的脱水率仅为20%,远低于LDHPAM的60%。     

锦州9-3油田产出聚合物对污水稳定性的影响研究

针对渤海锦州9-3油田聚合物驱生产污水组成特点,分别测定了不同相对分子质量、质量浓度及水解度的产出聚合物对含聚污水表观黏度、油滴粒径、Zeta电位、油水动态界面张力、油水平衡界面张力、油水界面扩张黏弹性等指标的影响。研究结果表明,含聚污水中产出聚合物的存在会增加含聚污水的黏度,吸附于油水界面增强含聚污水中O/W型乳液滴的Zeta电位,增加水化层以及油水界面膜强度,从而增强污水的乳化程度和稳定性,降低污水中油滴的聚并效率,增大了含聚污水的达标处理难度。     

高分子表面活性剂研究进展

本文综述了近十余年来通过表面活性单体聚合、亲水／疏水性单体共聚合及大分子化学反应三大类方法制备的新型高分子表面活性剂的结构和表面活性。已有的研究结果表明，一种单体均聚或不同种类单体嵌段、接枝、无规共聚，为合成具有指定结构和预期性能的高分子表面活性剂提供了巨大的可能性和选择性。     

Effect of polymer concentration on the properties of the crude oil-water emulsion

Abstract

In order to clarify the stability mechanism of the crude oil-water emulsion during polymer flooding, the effect of polymer concentration on the properties of the crude oil-water emulsion is systematically investigated by laboratory experiment, including the changes of the compositions of the crude oil, the parameters of interfacial tension, interfacial electrical property, interfacial expansion rheology and interfacial shear rheology, which can be used to characterize the change of the oil-water interfacial properties under the different polymer concentration. The results show that polymer molecules can be absorbed at oil-water interface to react with the asphaltene and resin to reduce the interfacial energy, increase the modulus of interfacial expansion rheology and interfacial shear rheology, and enhance the electronegativity of the oil-water film, which is contributed to emulsification, so that the emulsion is more stable with the increase of the polymer concentration.     

Water-in-Crude Oil Emulsion Stability Investigation

Abstract

The water-in-crude oil emulsion has great importance in the oil industry. The stability of water-in-crude oil emulsion is investigated over a wide range of parameters. These parameters are water concentration (10–50%), surfactant concentration (0.1–1%), mixing speed (500–2, 000 rpm), salt concentration (0–5%), polymer concentration (0–1, 000 ppm), and temperature (13–40^○C). The physical properties of water-in-crude oil emulsion in terms of density, viscosity, and interfacial tension are measured by Pycnometer, Ostwald viscometer, and spinning drop tensiometer, respectively. The stability of water-in-crude oil emulsion is studied for each case in details. This investigation shows that the presence of the emulsifying agent is necessary for stable emulsion, and stability gradually decreases with water concentration. The presence of 5% NaCl or 1, 000 ppm of Alcoflood polymer provides 100% stable emulsion. Emulsion stability reduces with temperature. Impeller type has a strong effect on the emulsion stability. S-curved blade impeller provides 100% stable emulsion for more than 2 days.     

Study the Influence of Some Polymeric Additives as Viscosity Index Improvers,Pour Point Depressants and Dispersants for Lube Oil

Abstract

In the present work, some polymeric additives were prepared as pour point depressants, viscosity index improvers and dispersant additives for lube oil, these additives prepared by copolymerization of maleic anhydride with different esters of acrylic acids and then amination. The molecular weights of the prepared copolymers were determined by gel permeation chromatograph (GPC). The efficiency of the prepared compounds as pour point depressants and viscosity index improvers was investigated. It was found that the efficiency of the prepared compounds as pour point depressants increases with decreasing the concentration of the prepared polymers, increasing the chain length of alkyl groups and increases with decreasing the molecular weight. The efficiency of the prepared compounds as viscosity index improvers increases by increasing the concentration of these additives and by increasing the molecular weight of polymer. It was found that the amination of polymer enhance the efficiency of the prepared additives as pour point, viscosity index, and dispersant for sludge.     

Synthesis and Evaluation of Some Polymeric Compounds as Pour Point Depressants and Viscosity Index Improvers for Lube Oil

Abstract

In the present study, some polymeric additives were prepared and used as pour point depressants and as viscosity index improvers for lube oil via copolymerization of maleic anhydride and vinyl acetate with different esters of acrylic acid. The molecular weights of the prepared copolymers were determined by GPC. The efficiency of the prepared compounds as pour point depressant and viscosity index improvers was investigated. It was found that the efficiency of the prepared compounds as pour point depressant increases with decreasing the concentration of the prepared polymers, increasing the chain length of alkyl groups, and increases with decreasing the molecular weight. The efficiency of the prepared compounds as viscosity index improvers increases by increasing the concentration of these additives and by increasing the molecular weight of the polymer.     

两亲聚合物泡沫稳定性及影响因素研究

针对泡沫驱两亲聚合物起泡剂的泡沫性能及影响因素开展了室内实验研究。结果表明:与普通表面活性剂泡沫相比,两亲聚合物泡沫的起泡体积较小,但其稳定性要远远优于表面活性剂泡沫;两亲聚合物泡沫性能随着两亲聚合物浓度的变化存在一个最优值,炼化Ⅰ型两亲聚合物在浓度为1.5 g/L时,其泡沫性能最优,且该泡沫体系具有良好的耐温、抗盐性;在高剪切下(转速大于4000 r/min)或煤油含量超过20%后,该泡沫体系的泡沫性能变差。     

Results of Bench-Scale Oil Displacement of Novel Polymer Solution in Daqing Oilfield

Abstract

In order to improve the dissatisfied oil displacement results of conventional low molecular weight polymers in some thin and poor reservoirs of the Daqing Oilfield in China, two new polymers with low molecular weight are introduced. A series of laboratory experiments were performed to evaluate the performance index and oil displacement results of the novel polymers. The results show that the new polymers have the characteristics of higher viscosity, better salt and shearing resistance, and better solubility than conventional polymers, and the viscoelasticity and shearing resistance of the new polymers increases with a decrease in molecular weight. Bench-scale oil displacement experiments indicate that the oil displacement results of the new polymers are better than those of the conventional polymers with the same molecular weight and the performance will be better with a decrease in molecular weight. Novel polymers have a favorable matching relationship with low-permeability reservoirs that are fit for wide application in thin and poor reservoirs.     

The Demulsification of Crude Emulsion of ASP Flooding by an Organic Silicone Demulsifier

Abstract

In order to enhance crude oil recovery, the dosages of alkali, surfactant, and polymer in the tertiary flooding are becoming increasingly higher, which makes the emulsion more difficult to demulsify. In this article the application of new organic silicone demulsifiers for the demulsification of produced crude emulsion of alkali-surfactant-polymer (ASP) flooding with higher concentrations of alkali, surfactant, and polymer was investigated. The result indicated that organic silicone demulsifiers whose hydrophile–lipophile balance (HLB) number ranged from 10 to 15 had a satisfactory effect on demulsification. The dewatering efficiency can be improved evidently by adding a demulsifier mixed with DC2 and JG31 whose volume ratio was 4:1. The dewatering efficiency for produced crude emulsion from ASP flooding could exceed 80% at 60°C in which the concentrations of alkali, polymer, and surfactant ranged from 1,200 to 9,000 mg/L, 400 to 1,000 mg/L, and 200 to 800 mg/L, respectively. The simulative industrialized experiment of the ASP flooding produced emulsion was made, the dewatering efficiency was 99.6%, and the oil content of the produced water was less than 100 mg/L.     

PEPTIZATION AND COAGULATION OF ASPHALTENES IN APOLAR MEDIA USING OIL-SOLUBLE POLYMERS

ABSTRACT

The asphaltene fraction of crude oil contains a variety of acidic and basic functional groups. During oil production and transportation, changes in temperature, pressure or oil composition can cause asphaltenes to precipitate out crude oil through the flocculation among these polar functional groups. In this study, two types of oil-soluble polymers, dodecylphenolic resin and poly (octadecene maleic anhydride), were synthesized and used to prevent asphaltenes from flocculating in heptane media through the acid-base interactions with asphaltenes. The experimental results indicate that these polymers can associate with asphaltenes to either inhibit or delay the growth of asphaltene aggregates in alkane media. However, multiple polar groups on a polymer molecule make it possible to associate with more than one asphaltene molecule, resulting in the hetero-coagulation between asphaltenes and polymers. It was found that the size of the asphaltene-polymer aggregates was strongly affected by the polymer-to-asphaltene weight (or number) ratio. At low polymer-to-asphaltene weight ratios, asphaltenes keep flocculating with themselves and with polymers until the floes precipitate out of solution. On the other hand, at high polymer-to-asphaltene weight ratios, asphaltene-polymer aggregates peptized by the extra polymer molecules can remain fairly stable in the solution.     

Investigation of Kinetic and Rheological Properties for the Demulsification Process

Chemical demulsification process is the most widely applied method of treating water in crude oil emulsions and involves the use of chemical additives to accelerate the emulsion breaking process. Hence, five demulsifiers were prepared in two steps. In the first step, the nonyl phenol was polymerized with formaldehyde to obtain five different molecular weights polymers. In the second step, the resulting polymers were ethoxylated with 50 ethylene oxide units and propoxylated with 10 propylene oxide units, yielding (D₁–D₅). The demulsification efficiency of these demulsifiers was investigated. The influence of viscosity on the droplet diameter for water-in-crude oil emulsion with three different ratios; 30:70, 50:50 and 70:30 (v/v) w/o emulsions were examined. The results showed that, the viscosity of w/o emulsion was strongly augmented by increasing volume of water before reaching the inversion point. The yield point which is required to start the flow decreases with decreasing water percent. The coalescence rate increases with increasing drop size for D₅ as a representative sample. Results show that, the droplet size increases with increasing water content. The efficiency of water separation increases as the molecular weight increase.     

Influence of polymers on the stability of Gudao crude oil emulsions

The influence of different types and concentrations of polymers on the stability of Gudao crude oil emulsion was investigated by measuring the volume of water separated from the emulsions and the interfacial shear viscosity of the oil/water interfacial film. Experimental results indicate that the simulated water-in-oil emulsion with 40 mg/L of partially hydrolyzed polyacrylamide （HPAM） 3530S could be easily broken by adding demulsifier C and was readily separated into two layers. However, HPAM AX-74H and hydrophobically associating water-soluble polymer （HAP） could stabilize the crude oil emulsion. With increasing concentration of AX-74H and HAP, crude oil emulsions became more stable. Water droplets were loosely packed in the water-in model oil emulsion containing HPAM 3530S, but water droplets were smaller and more closely packed in the emulsion containing AX-74H or HAP. The polymers could be adsorbed on the oil/water interface, thereby increasing the strength of the interracial film and enhancing the emulsion stability.     

Preparation of an SBS Latex–Modified Bitumen Emulsion and Performance Assessment

Abstract

For resolving the contradiction of the stability between styrene-butadiene-styrene (SBS)-modified bitumen emulsion and the concentration of SBS, a method of preparing SBS latex is provided in this article. Results showed that SBS latex had good stability properties and performance. The effect of emulsifier concentration on the storage stability showed that the maximum stability of SBS latex–modified bitumen emulsion (SBS-LMBE) was obtained at emulsifier weight concentration 1.0% and addition of SBS latex to bitumen emulsion enhanced the difficulty of emulsification. The effects of SBS latex on bitumen properties showed the penetration decreased, whereas the softening point and ductility at 5°C increased, which means that SBS latex plays a role in improving the properties of bitumen. Compared to the base bitumen, saturate and aromatic of evaporation residue of SBS-LMBE decreased. However, resin and asphaltene increased. Analysis of the relationship between the components and properties of bitumen showed that the components change caused by SBS latex was beneficial to the properties of bitumen. The colloidal index (CI) showed that SBS latex also made the colloidal system more stable.     

The Role of Asphaltene Solubility and Chemical Composition on Asphaltene Aggregation

Abstract

Asphaltenes from four different crude oils (Arab Heavy, B6, Canadon Seco, and Hondo) were fractionated in mixtures of heptane and toluene and analyzed by small angle neutron scattering (SANS). Fractionation appeared to concentrate the most polar species into the least soluble sub-fraction as indicated by elemental analysis. SANS results indicated a wide spectrum of asphaltene aggregate sizes and molecular weights; however, the less soluble (more polar) fraction contributed the majority of the species responsible for asphaltene aggregation in solution. This more polar, less soluble fraction is likely the major cause for many petroleum production problems such as deposition and water-in-oil emulsion stabilization. A comparison of molecular weight and aggregate size indicated that asphaltenes formed fractal aggregates in solution with dimensions between 1.7 and 2.1. This was consistent with the “archipelago” model of asphaltene structure. Resins were shown to effectively solvate asphaltene aggregates as observed by an increase in asphaltene solubility, reduction in aggregate size and molecular weight, and an increase in the fractal dimension to ? 3.     

DESTABILIZATION OF WATER IN BITUMEN EMULSION BY WASHING WITH WATER

ABSTRACT

In order to get more information about the mechanism of stabilization of water-in-diluted-bitumen emulsion, bitumen diluted with toluene (10%, 25%, and 50% in volume) was “washed” using different amounts of water (0.20% in volume). The washing water was emulsified and then separated by high-speed ultra-centrifugation. The supernatant was then used to create a second w/o emulsion with the addition of new water. Stability of the new emulsion was measured in terms of the water separation rate under a low centrifugal force

It has been found that a very stable w/o emulsion was obtained in original diluted bitumen. However, after the diluted bitumen was pre-washed with a few per cent of water, the second emulsion became unstable. This indicates a significant effect of pre-washing with water on emulsion stability, possibly through the removal of emulsion stabilizing agents. Based on analytical results such as surface tension, and FTIR spectra, it appears that a small fraction of bitumen, mostly polar compounds such as carbonic acids and other oxygen-containing compounds, are responsible for the emulsion stabilization. Emulsion stability decreases with increasing volume of washing water but increases with the bitumen concentration.     

Stability of oil-in-water emulsions by SDS compound

Abstract

Surfactants are often required to reduce emulsion viscosity and heavy-oil flow resistance in pipelines, thereby forming a stable oil-in-water emulsion under shear stress. This study aimed to quantitatively discuss and analyze the stability of oil-in-water emulsions and characterize them through the initial viscosity change rate K. The value of K was obtained based on the oil-rich-phase viscosity curves of oil-in-water emulsions comprising sodium dodecyl sulfate (SDS), heavy oil, and water at different time points. Results showed that a smaller K corresponded to a more stable emulsion according to analysis of the effect of the compound system on emulsion stability and the synergistic mechanism. We then combined with 1-pentanol and octyldecyl glucoside (APG0810) with SDS. Results showed that the K values of the emulsions decreased from 19.457 to 6.284, and 19.457 to 5.834, respectively, after mixing 6% 1-pentanol and 0.4% APG, respectively, with 0.14% SDS. Then, 0.14% SDS was compared with 1.2% a mass fraction of each of the three additives to form a compound system, and the K values were found to follow the trend K_{1-pentanol/SDS} > K_APG/SDS. Thus, the stability of APG/SDS oil-in-water emulsion was better than that of 1-pentanol/SDS emulsion.     

RAFT聚合制备嵌段聚合物结构对降滤失剂性能的影响

为了探究聚合物结构对降滤失剂性能的影响,选用AMPS作为阴离子组分、离子液体1-乙烯基-3-乙基咪唑溴盐（VeiBr）作为阳离子组分及AM作为中性组分,采用可逆加成断裂链转移自由基（RAFT）聚合法合成了一系列组成相同而结构不同的两性离子降滤失剂。通过调节单体加入顺序合成了3种结构精确、键接顺序不同、分子量分布窄且可控的聚合物结构,即无规共聚物、部分嵌段共聚物和完全嵌段共聚物,并评价了其流变性能、降滤失性能。结果显示在其他条件相同的条件下,无规分布聚合物的降滤失效果最好,而嵌段聚合物可用于制备高动塑比的流型调节剂。通过改变链转移剂加量,精确调节聚合物分子量,进一步分析了同一聚合物结构下不同分子量对其性能的影响。结果表明分子量越大,聚合物整体呈现黏度增大、降滤失性能得到改善的趋势。因此,无规序列结构的嵌段聚合物在钻井液降滤失剂中性能较好,同时分子量越大的聚合物更加具有优势,该研究为从结构出发研发高效降滤失剂提供了理论基础。