乳化稠油中多重乳滴的形成及对乳状液性质的影响

在新滩肯东451区块产出的平均含水58%的稠油(W/O乳状油)中以0.6 mg/g油的加量加入复配乳化剂HATJ72,在50℃搅拌2分钟转相形成的O/W乳状液,含大量复杂的多重乳滴,观测到了以水为最外相的七重乳滴.多重乳滴稳定性差,讨论了影响多重乳滴稳定性的因素:乳化剂及其加量;搅拌强度;温度;Ostwald熟化作用及形成原始乳滴时的油水比.由该区块净化稠油和含水7.2%的塔河稠油加水加乳化剂配制的O/W乳状液中乳滴结构比较简单,绝大多数为W/O/W型.与由肯东稠油加水加乳化剂配制的O/W乳状液相比,肯东含水(58%)稠油加乳化剂转相形成的含水相同(35%)的O/W乳状液,表观黏度较低且黏度较不稳定.简介了获得成功的肯东451站含水稠油乳化降黏集输试验.在含水58%的稠油中按0.6 mg/g油的加量加入乳化剂HATJ72和自由水,转相形成O/W乳状液,输送温度50℃,乳化液滴结构复杂,乳状液稳定性较差,输送至下游5公里处时,管道垂直方向上含水、油、水滴数量、黏度已有很大差异.液滴结构复杂、乳状液稳定性差,是自由水引起的,因此应控制掺水量.     

稠油水包油型乳状液表观黏度的影响因素及预测模型

通过单因素实验,系统分析了两性/非离子复配表面活性剂含量、无机/有机复配碱含量、含油率、搅拌速率、乳化温度对稠油水包油(O/W)型乳状液表观黏度的影响。在单因素实验基础上,进行了六因素三水平的正交实验,并应用SPSS软件进行方差分析及非线性回归,进一步分析各因素对乳状液表观黏度影响的显著程度,得到稠油O/W型乳状液的表观黏度预测模型,进而从理论上分析了各因素对乳状液表观黏度的影响规律。结果表明,随着复配表面活性剂含量的增加,乳状液表观黏度增大;复配碱对乳状液表观黏度的影响具有双重性,既能促使界面上活性物质发生电离,又能压缩扩散双电层,结果取决于两者的相互竞争;随着含油率的增加,乳状液表观黏度增大;搅拌速率在500~1000 r/min范围内,随着搅拌速率的增加,乳状液表观黏度增大,在1000~1500 r/min〖JP〗范围内,表观黏度变化不大;乳化温度升高导致乳状液表观黏度降低。稠油O/W型乳状液的表观黏度预测模型预测的表观黏度与实验结果吻合。     

大庆西部斜坡稠油地层流动性影响因素实验研究

针对大庆西部斜坡稠油在开采过程中与地层水和注入水乳化生成高黏的油包水型乳状液降低地层流动性的问题,通过流变性实验和岩心流动实验,研究了乳化、温度及地层渗透率对稠油黏度和地层流动性的影响规律,明确了原油在地层中流动困难的原因及改善流动性的技术方向。结果表明：含水乳化和温度是影响其黏度的主要因素,温度由30℃上升至120℃,脱水稠油黏度降低了95.5%;当含水率低于70%时,原油与水形成油包水型乳状液,含水率越大黏度越大,含水率为70%的稠油的黏度是脱水黏度的30倍左右;地层渗透率、温度及含水乳化对原油地层流动性具有显著的影响,地层渗透率越低、温度越低、含水乳化越严重,原油流动性越差,不同温度和含水率下的采油指数相差可达10倍以上。因此,促使含水稠油乳状液转相是油田降黏增产的有效途径。研究成果对同类油藏开发具有重要的指导意义。      

稠油O/W乳状液现场管道输送试验分析

综合含水68%～72%的胜利孤东新滩稠油与水混合液,在加入乳化剂HA78浓度为400～800mg/L、现场搅拌条件下,可转相形成较为稳定的O/W乳状液。由于含水率和搅拌强度的变化,在相同样加剂浓度下,现场条件配制的O/W乳状液较试验室配制的表观黏度低,其非牛顿性弱,稳定性有所下降,表观黏度随温度下降变化不明显。在加剂400～800mg/L范围减阻效果与乳化剂浓度成正比,混合方式对减阻效果影响不大。对于试验管道垦东451—东4联集输管道而言,从输送压降分析,在含水量相同的条件下,加入乳化剂后油水混合输送减阻效果优于掺热水输送效果,可以实现全越站输送。管流条件下,在O/W乳状液比较稳定时,减阻主要以降黏减阻为主,而在O/W乳状液不稳定时,主要以管壁与稠油之间形成水膜减阻为主。     

季铵盐阳离子聚合物防膨剂对 W/O乳状液稳定性的影响

为揭示季铵盐阳离子聚合物防膨剂对热采稠油乳状液稳定性的影响规律,根据南堡35-2油田热采现场采出液特征,采用高温高压可视相态釜模拟配制油包水乳状液,研究了季铵盐阳离子聚合物防膨剂对油水界面张力、界面剪切黏度及乳状液表观黏度和破乳脱水率的影响。结果表明,随着防膨剂浓度的增大,油水间的界面张力降低,界面剪切黏度增大;防膨剂浓度一定时,随着剪切速率的增大,界面剪切黏度增大并最终趋于稳定。温度对乳状液体系的性能影响较大:防膨剂在55℃时几乎对原油的乳化不产生影响,防膨剂溶液与原油形成的乳状液不稳定;在乳化温度为100℃和150℃下形成的乳状液稳定性高,且其表观黏度随防膨剂浓度的增大而增大;防膨剂浓度一定时,随着乳化温度升高,乳状液的表观黏度明显增大,脱水率降低,150℃时含0.5%~10%防膨剂乳状液的脱水率均为0,稳定性良好。季铵盐阳离子聚合物防膨剂能降低油水间的界面能,提高界面膜强度,增加W/O型乳状液的稳定性。     

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。     

聚合物对W/O乳状液稳定性的影响规律研究

根据孤岛聚合物驱现场采出液特征,室内模拟配制了W/O乳状液,研究了聚合物对乳状液表观黏度、液滴直径及油水界面黏弹性质的影响规律.结果表明,采出液中的残留聚合物可显著提高乳状液的表观黏度,当聚合物浓度为400 mg/L时,乳状液黏度达到极大值;大于400 mg/L时,乳状液的黏度不再增大.聚合物浓度增大使W/O乳状液的水珠粒径减小、分布集中;聚合物浓度大于300 mg/L时,水珠粒径基本不变.聚合物可改变油水界面膜的流变性,增强油/水界面的黏弹性模量和复数黏度,增大界面膜的强度,增加乳状液的稳定性.以上效应导致含聚合物的采出液乳化更加稳定,破乳更加困难.     

有机碱和无机碱对原油的乳化性质及对聚合物黏度的影响

以乙二胺作为有机碱,NaOH作为无机碱,利用乳化实验和黏度测量实验,对两种碱与稠油的乳化行为及两种碱对聚合物黏度的影响进行了研究。结果表明,乙二胺的加入基本不增加溶液矿化度,其质量分数的增加不会促使油包水乳状液的形成,且在NaCl质量分数不大于1.2%时,0.2%~1.0%的乙二胺可将稠油乳化成较稳定的水包油乳状液;而NaOH的加入会增加溶液的矿化度,即使溶液中不加NaCl,0.6%以上的NaOH会促使油包水乳状液的形成,不利于水包油乳状液的稳定,且不同NaCl质量分数下1%的NaOH溶液都会把稠油乳化成油包水乳状液。溶液中NaOH的加入会大大降低聚合物的黏度,当NaOH质量分数为1%时,聚合物的黏度会降低一半多;而乙二胺的加入基本不增加溶液矿化度,不仅不会降低聚合物黏度,反而可以使聚合物的黏度有所上升。由此可知,乙二胺在原油开采及提高原油采收率方面相对NaOH有较大优势。     

石油乳状液的黏度模型

在大量文献调研的基础上,总结了化学复合驱数值模拟中应用的石油乳状液黏度模型,包括黏度-含水率模型、黏度-剪切速率模型以及黏度-含水率-剪切速率模型.研究表明化学驱中生成的乳状液的黏度受到多种因素影响,其中最为重要的是体系的含水率(或含油率)、剪切速率和温度;对于不同的含水条件,乳状液的黏度表达式不同;随着含水率的增加,将出现黏度突变的临界含水率,此临界点对应水包油型与油包水型乳状液之间的转变.建立了化学驱数值模拟软件中对应不同含水阶段的乳状液黏度模型.图4参13     

高含蜡石蜡乳状液的研制及影响因素探讨

以石蜡为主要原料,采用剂在油中法制备了石蜡乳状液.考察了乳化剂类型和用量、乳化水用量、乳化温度、乳化时间、搅拌速度对石蜡乳化效果的影响.结果表明,复配乳化剂优于单一乳化剂,且复配-Ⅱ型乳化剂效果最好.并确定了最佳乳化工艺条件:复配-Ⅱ型乳化剂用量10%,乳化水用量65%～70%,乳化温度90℃,乳化时间30min,搅拌速度1000r/min.在此条件下,石蜡乳状液蜡含量为30%～35%,具有较好的稳定性和分散性.     

基于能量及原油物性定量分析的原油乳化含水率预测模型

 原油-水两相体系的乳化特性与原油物性密切相关,以流动状态下的原油乳化含水率来表征原油-水两相体系的乳化特性,针对高含水原油-水两相体系,通过实验研究了乳化过程消耗的机械能对原油乳化含水率的影响。研究表明,不同剪切条件下的原油乳化含水率可以与消耗的机械能进行定量关联,并且可以采用幂律关系式进行描述,该关系式中的2个待定参数与原油物性密切相关。确定了用沥青质胶质含量、蜡含量、机械杂质含量、原油酸值、原油全烃平均碳数这5个典型参数来表征原油物性。通过回归分析,建立了待定参数与原油物性之间的定量关系,从而确定了原油乳化含水率的预测模型,即φE=c₁E^c2。     

基于原油物性定量分析的原油乳状液转相点预测模型

以流动状态下的原油乳化含水率来表征原油-水体系的乳化特性,通过实验研究了体系含水率对原油乳化含水率的影响。研究表明：当体系含水率较小时,原油能将水相全部乳化,形成稳定的W/O乳状液;而当体系含水率超过一定的临界值后,原油乳化含水率急剧减少,形成的是W/O/W多重乳状液;该临界体系含水率,即为原油乳状液从W/O型向W/O/W型转变的转相点。确定了5个典型参数来表征原油物性,分别是沥青质胶质含量、蜡含量、机械杂质含量、原油酸值、原油全烃平均碳数。通过回归分析,建立了原油乳状液转相点预测模型,预测结果的平均相对偏差为3.2%。     

应用降粘剂提高大港稠油油藏水驱采收率

在对大港官109-1断块稠油组成及结构进行分析的基础上,针对油藏高温、高矿化度及水驱采出程度低的特点,研制出一种降粘剂。在含水量大于30%及降粘剂加入量大于1 000 mg/L（占油水总质量）的条件下,能使油水体系形成稳定的O/W乳液,降粘率大于97%,且降粘剂的存在对采出液的破乳脱水没有负面影响。岩心驱油实验结果表明,降粘剂驱油体系比水驱体系稠油采收率提高22%以上,说明使用降粘剂可降低油藏稠油粘度,改善水/油流度比,提高波及系数,明显改善水驱效果。     

The Formation of Waxy Crude Oil-in-water Emulsions for the Reduction of Pour Point and Viscosity

Waxy crude oil is characterized by high pour point and poor flow properties, which bring great difficulty to the oil exploitation and transportation. In this study, the fluidity of waxy crude oil with the pour point of 47°C was highly improved by emulsification with synthetic formation water used as aqueous phase. It was found that the combination of CAO-35 and sodium oleate was an effective emulsifier mixture to form stable waxy crude oil-in-water emulsion and when the mass ratio of oil to water was 7:3, the optimum composition of emulsifying additives with respect to the total mass of the emulsion was obtained as follows: emulsifier mixture (the mass ratio of CAO-35 to sodium oleate was 8:2) 0.4% (w/w), sodium triphosphate 0.028% (w/w), NaOH 0.05% (w/w), and polyacrylamide 0.15% (w/w). Diverse factors affecting the pour point of the formed emulsion were also studied. It was found that the pour point of emulsion increased as oil content increased and the optimum mixing speed and cooling rate were 600 rpm and 0.5°C/min, respectively. Under the optimum emulsifying conditions, when mixing speeds were 250 and 600 rpm, respectively, by forming O/W emulsions with the oil content of 70%, the pour point reductions were 20 and 25°C, respectively, and the corresponding viscosity reductions were 89.79% and 97.46% (40°C), respectively. Thus the pour point and viscosity of waxy crude oil are obviously reduced by forming oil-in-water emulsion, which is highly promising for the exploitation and transportation of waxy crude oil.     

搅拌测量法测定油水混合液流动特性

对于非均匀混合(乳化)、不稳定的油水两相体系,传统的黏度计无法测量其黏度。通过搅拌可以维持油水两相的均匀混合状态,并且搅拌轴的扭矩反映了流体的当量黏度。基于这一原理,建立了搅拌测量油水混合液流动性的方法,包括搅拌桨叶类型的选择、根据搅拌轴扭矩确定一定搅拌转速下的黏度、根据搅拌转速及流体黏度确定搅拌槽的平均剪切率。针对单相原油和油水混合液,将该方法的测量结果分别与同轴圆筒黏度计和试验环道的测试结果进行了对比,验证了其可靠性。应用该方法,对高含水油水混合液在不同温度和含水率条件下的流动性进行了测量,结果具有良好的规律性。     

Mechanism of the viscosity reduction with ternary compound in the sulfonate-straight chain alcohol-alkaline compound system

Research shows that the viscosity greatly reduction of viscous crude oil can improve the exploitation and promote the fluidity. We studied the effects and the mechanism of viscosity reduction of viscous crude oil emulsion after introducing the ternary compound of sulfonate-straight chain alcohol-alkaline as the viscosity reducer. Results showed that the best emulsifying performance can be achieved using 5% 1-pentanol. 0.2% of Na₂CO₃ and DEA shows the strongest emulsification ability of the O/W emulsion. The use of AOS, straight chain alcohol and petroleum carboxylate resolves diffusion on the oil-water interface, which can form a dense surfactant of single molecular layer to reduce the interfacial tension and prevent the phase change of the emulsification. When the mass fraction of AOS, Na₂CO₃, DEA and 1-pentanol were 0.2%, 0.25%, 0.2% and 5% respectively, the viscous crude oil would achieve the best effect of viscosity reduction.     

Influence of Water Content and Temperature on Stability of W/O Crude Oil Emulsion

Water content of W/O crude oil emulsion and temperature have great influence on stability of the W/O crude oil emulsion and the subsequent demulsification process especially for oil-water treatment centers using a two-step sedimentation demulsification process in Jilin oilfield. Electrical microscope and Turbiscan stability analyzer were employed to investigate the influence of water content and temperature on stability of synthetic W/O emulsion. The results show that the average water droplets size decreases when water content decreases, the emulsion stability decreases when water content or holding temperature increases, and the emulsion stability constant and the temperature have a linear relationship.     

Experimental investigation of the effects of various parameters on viscosity reduction of heavy crude by oil–water emulsion

The effects of water content, shear rate, temperature, and solid particle concentration on viscosity reduction(VR) caused by forming stable emulsions were investigated using Omani heavy crude oil. The viscosity of the crude oil was initially measured with respect to shear rates at different temperatures from 20 to 70 C. The crude oil exhibited a shear thinning behavior at all the temperatures. The strongest shear thinning was observed at 20 C. A non-ionic water soluble surfactant(Triton X-100) was used to form and stabilize crude oil emulsions. The emulsification process has significantly reduced the crude oil viscosity. The degree of VR was found to increase with an increase in water content and reach its maximum value at 50 % water content.The phase inversion from oil-in-water emulsion to water-inoil emulsion occurred at 30 % water content. The results indicated that the VR was inversely proportional to temperature and concentration of silica nanoparticles. For water-in-oil emulsions, VR increased with shear rate and eventually reached a plateau at a shear rate of around350 s-1. This was attributed to the thinning behavior of the continuous phase. The VR of oil-in-water emulsions remained almost constant as the shear rate increased due to the Newtonian behavior of water, the continuous phase.     

流动条件下原油乳化含水率与水相组成的关系

油田采出水中含有大量的无机阴、阳离子,如Na⁺、Ca²⁺、Mg²⁺、Cl^-、HCO₃^-等,这些离子对油-水两相体系的乳化特性有重要影响。以流动条件下原油的乳化含水率表征油-水两相体系的乳化特性,针对以CaCl₂、NaHCO₃、Na₂SO₄、MgCl₂和NaCl共5种盐溶液为水相、存在游离水的高含水油-水两相体系,通过搅拌实验,研究了水相组成对原油乳化含水率的影响。研究表明,这些无机盐的加入可以使原油的乳化含水率增大,但随着矿化度的增大,原油乳化含水率增大的速率逐渐减小;这5种无机盐对流动条件下原油乳化含水率的影响大小排序为:NaCl>(Na₂SO₄、NaHCO₃)>MgCl₂>CaCl₂;酸性环境不利于原油的乳化,而碱性环境能够促进原油的乳化,一定矿化度条件下,pH值越高,其乳化含水率越高。对于一定矿化度下的高含水油-水两相体系,不同剪切条件下的乳化含水率可以与搅拌槽内的黏性流动熵产率进行归一化关联,并且二者符合幂律关系。通过回归分析得到了该幂率关系式中的待定参数与水相组成之间的定量关系式。     

微观液滴分布对含蜡原油乳状液流变性的影响

通过显微镜观察并拍摄原油乳状液的微观结构图像,研究了乳状液体系分散相液滴大小及分布规律,以及微观液滴分布对乳状液体系流变性的影响机理。W/O型原油乳状液中含水率增加,引起内相液滴个数增多,小液滴所占的比例减小,相对大的液滴所占的比例增大;搅拌转速的增大,使体系内相液滴个数增多,平均液滴直径减小。通过测试在固定搅拌条件下制备的不同含水率的3种含蜡原油乳状液在原油凝点附近温度屈服特性和触变性等流变特性,可以发现随含水率的增大,乳状液体系屈服应力增大、触变性增强,且含水率越高,变化的趋势越明显。通过测试不同搅拌转速下制备的含水率为30% 的原油乳状液在原油凝点附近温度的触变性,可以看出随搅拌转速的增大,体系经受同等剪切速率剪切时对应的剪切应力增大、触变性增强。进一步建立了屈服应力与测试温度、含水率之间的关系式,其平均相对误差为9.83%。