Al2O3纳米颗粒与表面活性剂对O/W乳状液稳定性的影响

为了提高原油乳状液的稳定性,研究了亲水和疏水两种氧化铝纳米颗粒在阴离子表面活性剂十二烷基苯磺酸钠(SDBS)、阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)和非离子表面活性剂烷基酚聚氧乙烯醚(OP-10)中的分散稳定性,并用氧化铝纳米流体、液体石蜡和OP-10制得O/W型乳状液,考察了亲水与疏水纳米颗粒和OP-10对乳状液稳定性的影响。结果表明,表面活性剂类型与浓度对氧化铝纳米颗粒分散效果的影响较大,OP-10的分散性较好。O/W乳状液的稳定性与纳米颗粒和表面活性剂密切相关。在一定浓度下,随着纳米颗粒和表面活性剂浓度增加油水界面张力降低,乳状液的稳定性增强;高浓度的纳米颗粒和表面活性剂会使油水界面张力和乳状液析水率增加,稳定性降低;0.3%OP-10复配0.2%疏水氧化铝纳米颗粒形成的乳状液稳定性较好。与亲水氧化铝纳米流体相比,疏水氧化铝纳米流体具有更高的分散稳定性和更强的稳定乳状液的能力。     

2-D智能纳米黑卡在低渗透油藏中的驱油性能评价*

针对低渗透油藏渗透性差、孔喉狭小和岩层致密等特点,研制了片状2-D智能纳米黑卡驱油体系。研究了2-D智能纳米黑卡的微观结构、润湿性、界面性质、稳定性、乳化降黏性,通过一维岩心驱替实验考察了岩心渗透率、纳米黑卡浓度以及原油黏度对2-D智能纳米黑卡溶液驱油效果的影响。研究结果表明,纳米黑卡尺寸约为60 nm×80 nm×1.2 nm,其与油水界面形成"面-面"接触,界面作用极强。纳米黑卡比表面积大,能在水相中均匀分散,可发挥润湿反转、乳化降黏、降低界面张力、降压增注等多重功效。岩心驱替实验结果表明,岩心渗透率、纳米黑卡浓度和原油黏度对驱油效果均有影响。在岩心渗透率为25×10^-3μm^2、纳米黑卡加量为0.005%和原油黏度为25 mPa·s时,2-D智能纳米黑卡溶液的驱油效果较好,原油采收率增幅为18.10%。片状2-D智能纳米黑卡可充分发挥"智能找油"功能,适用于低渗透油藏提高驱油效率。图10表2参28。     

化学法改进稠油开采技术

1.降粘剂的筛选及乳化油的稳定性 （1）乳化降粘剂的静态稳定性筛选.选择的降粘剂应具有以下特点：①较高的表面活性,其亲水能力大于亲油能力;②较好的破乳分散效果,能使原油形成稳定的O/W型活性膜或将W/O型乳化油反转成O/W型乳化油,使原油粘度降低;③使原油不易附着在管壁上,达到降低摩阻的目的.     

2-D智能纳米黑卡微观驱油机理可视化实验*

由中国石油大学(北京)非常规油气科学技术研究院自主研发的2-D智能纳米黑卡是一种具有尺寸小、比表面积大等优势的片状纳米材料(尺寸为80×60×1.2 nm,比表面积约57 m2/g)。本文使用不同孔隙度、渗透率的二维可视化模型,进行2-D智能纳米黑卡微观驱替可视化实验。通过分析岩心渗透率、颗粒浓度和注入速率等因素对驱油效果的影响,研究在微观条件下该纳米材料的微观渗流机理和运移规律。研究表明,该材料具有优异的亲水亲油平衡性,能够改变岩石表面润湿性,在两相界面产生楔形渗透压,形成微观回旋流,相对于以往如SiO2等球型纳米颗粒,具有更大的表面接触性。2-D智能纳米黑卡可有效驱替地层剩余油,剥离微小孔喉壁面上的油膜,扩大低渗层波及体积,提高原油采收率。图38参22     

石油磺酸盐弱碱体系采出液分离及影响因素

跟踪石油磺酸盐弱碱体系三元复合驱矿场试验主段塞注入阶段,对采出液进行了系统研究,模拟了碱、表面活性剂和聚合物对采出液油水分离特性的单一和协同影响。结果表明:碱与原油中的天然物质反应生成界面活性物质,降低油水界面张力,使原油乳状液乳化强度增大,O/W型乳状液中的分散相油珠粒径显著下降,稳定性增强;在低表面活性剂质量浓度下,活性剂吸附到油水界面上顶替了部分原油中的天然表面活性物质及碱与原油反应生成的界面活性物质,插入到油水界面上胶质和沥青质聚集体之间,降低了胶质和沥青质聚集体之间的作用力,但加强了界面黏弹性,使原油乳状液稳定性增强;聚合物使水相具有黏弹性,使得水滴难以破裂,导致原油乳状液中水滴尺寸增大,稳定性下降。     

长庆油包水乳状液的稳定性与沥青质含量的关系

以长庆轻质原油为例,探讨了原油组分对乳状液稳定性的影响规律;采用煤油萃取轻质组分及二 甲苯溶解沥青质两种方法证实了沥青质是稳定轻质油包水乳状液的主要因素;采用流变仪、布氏黏度计 和光学显微镜等仪器测定了含水原油乳状液界面膜强度、油相黏度和乳状液尺寸。结果表明,取决于沥 青质的油 水界面膜强度和油相黏度是影响原油乳状液稳定性的主要因素,沥青质含量越高,油 水界 面膜强度和油相黏度越大,乳状液越稳定。     

稠油乳化驱油机理及室内效果评价

渤海L油田属于稠油油藏,存在水驱开发程度较低的问题。为了改善油水差异的问题,开展了稠油乳化剂与储层岩石润湿能力、原油之间乳化能力、界面张力和降黏效果实验及机理研究。结果表明,稠油乳化剂一方面可以使亲油岩石转变为亲水岩石,另一方面降低亲水岩石的亲水性,有利于将原油与岩石分离,达到提高洗油效率的目的。当"油:水"低于"4:6"时,稠油乳化剂溶液与原油可形成W/O/W型乳状液,大幅度降低稠油黏度,达到改善稠油储层内流动性和扩大宏观波及体积的目的。稠油乳化剂与原油在多孔介质内接触并发生乳化作用,乳状液通过吼道时存在"贾敏效应",致使局部渗流阻力增加和微观波及效果提高。     

DPS-1型原油破乳剂

大庆油田目前原油采出液大部分井站综合含水率已超过85％,部分油井采出液综合含水率已达到了90％以上。随着采出液含水率的上升,原油采出液的类型也发生了变化,已由过去的油包水型(W/O)为主转变为水包油型(O/W)和水包油包水型(W/O/W)多重乳状液。而目前     

原油乳状液稳定性影响因素研究的新进展

乳化剂的存在是生成稳定乳状液的必要条件。研究表明:胶质和沥青质的协同作用很强,胶质对沥青质的分散能力可以阻碍沥青质的聚并和缔和。随着原油相黏度增加,阻碍了界面膜的排液,油滴间难以聚并,使W/O型乳状液更加稳定。在界面面积不变的情况下,油水两相间具有较低的界面张力,降低界面能,可增加界面膜的强度,这不仅有利于增加乳液的热力学稳定性,同时还能保持乳状液动力学稳定性不变,使乳状液的稳定性增加。对于W/O型乳状液,随着十二烷基苯磺酸钠(SDBS)浓度的增加,电导率不断提高,比较容易形成胶束。在调配驱油体系时,碱的加量应控制在一定范围内,以最大程度地发挥其驱油效果。     

聚酰胺-胺星形聚醚原油破乳剂的合成与性能

以1.0G、2.0G、3.0G 乙二胺为核制备了星形大分子聚酰胺-胺,并与环氧丙烷、环氧乙烷进行烷氧基化反应制备了一系列具有多分支结构的二嵌段聚醚类破乳剂。采用浊点法测定了系列破乳剂的亲水亲油平衡值,单滴法测量了降低油水界面膜强度的能力,针对油包水型原油乳状液进行了破乳性能研究。结果表明:该系列聚醚破乳剂具有良好的界面活性,对油包水型原油乳状液脱水率超过90%,具有良好的破乳性能和适应性;破乳剂起始剂聚酰胺-胺代数越高,分支越多,所合成的聚醚破乳剂性能越好;随着聚酰胺-胺的代数及破乳剂质量浓度的增加,油滴液膜排液时间缩短,半生命期减小,破裂速率常数增大。     

聚醚结构对油水界面性能及稠油降黏效果的影响

为深入认识化学驱稠油乳化降黏的作用机制,考察了3种不同结构的聚醚与稠油的界面张力和界面扩张流变性质,测定了聚醚溶液与稠油形成的乳状液的稳定性、粒径和黏度.结果表明,聚醚类表面活性剂具有较长的柔性氧乙烯(EO)链和氧丙烯(PO)链,能形成界面"亚层",油水界面膜以弹性为主,易与稠油形成稳定的O/W乳状液,显著降低稠油黏度...     

稠油乳状液的流变性试验研究

用四种不同的粘性原油乳状液进行了乳状液流变性的研究。结果表明，剪切应力与剪切速率的关系和液滴尺寸大小密切相关，视粘度和非牛顿性随液滴尺寸减小而增大。大部分乳状液在低剪切速率下（＜５０Ｓ－１）剪切变稀，当剪切速率超过５００ｓ－１时呈现牛顿流体性质。因此．液滴尺寸是乳状液流变性研究中的重要因素。     

Viscosity of Concentrated Emulsions: Relative Effect of Granulometry and Multiphase Morphology

Abstract

High viscosity and high density make heavy and extra heavy crude oils very difficult to produce. They cannot be pumped in their natural state and advanced technologies are required. Formation of oil-in-water emulsions is one of them. A typical emulsion contains 65% of dispersed phase and has a viscosity lower than 500 mPa.s. Current research is aimed at increasing the crude oil content at reduced costs with still good stability and low viscosity. Consequently, an experimental study was dedicated to the relationship between the structure and the rheological properties of heavy oil emulsions. Particular attention was paid to process parameters employed to prepare emulsions. Depending on the shear device, various emulsions have been obtained, either simple or multiple, monodisperse or bimodal. The resulting viscosity is discussed. It is particularly low when the emulsion is either coarse and unimodal or fine and simple. The highest viscosity is obtained when the emulsion is fine and multiple. The experimental results confirm that both composition variables and process parameters have to be taken into account to minimize viscosity of heavy oil emulsions.     

EFFECT OF ASPHALTENE AND RESINS ON THE STABILITY OF WATER-IN-WAXY OIL EMULSIONS

Asphaltene, resins and paraffin waxes, their mutual interactions and their influence on the stability of water-in-oil emulsions have been studied. 20 wt % paraffin wax dissolved in decalin was used to model the waxy crude oil. Asphaltene and resins separated from a crude oil were used to stabilize the water-in-oil emulsions. Synthetic formation water was utilized as the aqueous phase of the emulsion. The emulsion stability increased with increasing the concentration of asphaltene with a subsequent decrease in the average particle size distribution of the emulsion. Resins alone are not capable of stabilizing the emulsion, however, in the presence of asphaltene they form very stable emulsions. Dynamic viscosity and pour point measurements provided evidence for resins-paraffin waxes interactions. Asphaltene in the form of solid aggregates form suitable nuclei for the wax crystallites to build over with a mechanism similar to that of paraffin wax crystal-modifiers. As asphaltene are polar in nature they are derived at the oil/water interface which was proved by the ability of asphaltene to reduce oil/water interfacial tension. Consequently, nucleation of the wax crystallites by asphaltene and resins at the interface will add to the thickness of the oil-water interfacial film and hence increase the stability of the emulsion.     

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.     

STABILITY AND RHEOLOGY OF HEAVY CRUDE OIL-IN-WATER EMULSION STABILIZED BY AN ANIONIC- NONIONIC SURFACTANT MIXTURE

The stability and rheology of an Egyptian Heavy crude oil-in-water emulsions stabilized by an anionic (TDS) and a nonionic (NPE) surfactants individually or in a mixture have been studied. The study reveals that, the viscosity of the crude oil decreases when it is emulsified with water in the form of an oil-in-water type of emulsion. The stability of the oil-in-water emulsion increases as the surfactant concentration and speed of mixing of the emulsion increases. Fresh water and synthetic formation water have been used to study the effect of aqueous phase salinity on the stability and viscosity of the emulsion. Surfactant dissolved in synthetic formation water has been utilized to find out the possibility of injecting the surfactant into a well bore to effect emulsification in the pump or tubing for enhancing the production of heavy crude oils as oil-in-water emulsion. The study revealed that, the viscosity of the emulsion containing fresh water is always less than that containing formation water, these findings have been correlated with the crude oil/water interracial tension (IFT) measurements The decreased IFT value results in a decrease in the average particle size of the dispersed crude oil leading     

Modeling of flow of oil-in-water emulsions through porous media

Formation and flow of emulsions in porous media are common in all enhanced oil recovery techniques.In most cases,oil-in-water(O/W) emulsions are formed in porous media due to oil-water interaction.Even now,detailed flow mechanisms of emulsions through porous media are not well understood.In this study,variation of rate of flow of O/W emulsions with pressure drop was studied experimentally,and rheological parameters were calculated.The pressure drop increases with an increase in oil concentration in the O/W emulsion due to high viscosity.The effective viscosity of the emulsion was calculated from the derived model and expressed as a function of shear rate while flowing through porous media.Flow of O/W emulsions of different concentrations was evaluated in sand packs of different sand sizes.Emulsions were characterized by analyzing their stability,rheological properties,and temperature effects on rheological properties.     

Rheological behaviour of crude oil: Effect of temperature and seawater

The effect of temperature and seawater on rheological behavior was investigated in this work for four samples of crude oil from Algerian Sahara. The Newtonian model was used to fit the shear stress dependence on the shear rate for temperature range between 20 and 100°C. The temperature increase leads to a decrease in the dynamic viscosity of crude oil. The temperature dependence of dynamic viscosity was fitted by the Walther equation. For crude oil emulsion, the Herschel-Bulkley model was used to fit the shear stress dependence on the shear rate for volume fraction of seawater between 30 and 70%. The increase in the volume fraction of seawater induces not only an increase in the yield stress and the consistency index of crude oil emulsions but also a decrease in the flow index of crude oil emulsions.