孤东油田稠油极性四组分测定方法及其乳化特性研究

稠油油藏高效、经济的开发一直是油田企业研究的技术难题之一,胜利孤东油田稠油油藏由于其胶质、沥青质含量均高于国内主要稠油平均值,有其特殊性,开采难度也更大.文章通过大量室内实验,确定了稠油极性四组分(饱和分、芳香分、胶质、沥青质)的测定方法和分离方法,并采用元素分析、红外光谱分析等手段深入研究了稠油极性四组分的乳化特性、乳化剂对四组分乳化特性的影响.研究结果表明,孤东稠油极性四组分乳状液稳定性次序为饱和分＜沥青质＜芳香分＜胶质＜原油,原油中胶质与沥青质分子通过氢键形成的缔合,对原油的黏度有重要影响.乳化剂OP对稠油极性四组分均具有强烈的乳化促进作用,使W/O型乳状液转变为O/W型,达到了乳化降黏效果.     

乳化剂对超稠油四组分乳化性能的影响

通过乳状液透光率和界面张力考察胜利油田罗家超稠油极性四组分质量分数为2％的甲苯模型油加OP乳化剂前后与地层水、碱水的乳化性能，发现乳化荆对四组分都起到了强烈的乳化促进作用。加200mg／LOP乳化荆后，四纽分模型油透光率变化由大到小的顺序是：沥青质〉芳香分〉肢质≈饱和分；与地层水的界面张力降幅由大到小的顺序是：饱和分≈胶质〉芳香分〉沥青质：与碱水的界面张力降幅由大到小的顺序是：沥青质〉饱和分≈胶质〉芳香分。0P乳化荆使W／O型乳状液转变为0／W型，提高了稠油乳化程度，便于稠油的化学乳化开采和输送。     

孤岛原油正庚烷和正戊烷沥青质乳化能力研究

从孤岛原油中分离出正戊烷和正庚烷沥青质，元素分析和红外光谱分析结果表明，相对分子质量较大的正庚烷沥青质，含杂原子和极性基团较多。将两种沥青质溶于甲苯配制的模型油，分别与蒸馏水、模拟地层水、0～900mg／LHPAM溶液、0～500mg／L黏土液按1：10体积比充分乳化，测定静置时水相（水包油乳状液）透光率，据以考察沥青质的乳化能力，结果表明：正庚烷沥青质的乳化能力强于正戊烷沥青质；矿化离子使沥青质的乳化能力减弱；随聚合物浓度增大，沥青质乳化能力增强；黏土在浓度小于200mg／L时使乳化能力减弱，浓度大于200mg／L时使乳化能力增强。模型油与HPAM溶液间的界面张力，在聚合物浓度100mg／L时有最小值，在500mg／L时有最大值，正庚烷沥青质模型油的界面张力随聚合物浓度的变化较剧烈。正庚烷模型油在聚合物溶液中的乳化油滴直径分布范围较正戊烷模型油窄，聚合物浓度较大时，油滴直径分布范围较宽。正庚烷沥青质模型油与黏土液闸的界面张力，在黏土液浓度增至300mg／L时略有升高，浓度继续增大时大幅升高，而正戊烷模型油的界面张力在黏土液浓度300mg／L时有最低值。图9表3参7。     

渤海典型稠油活性组分对油水界面性质及乳状液稳定性的影响

为了揭示原油组分分子组成与各组分界面性质、乳化性能间的关系,阐明油水界面性质变化和原油乳化机理,用极性分离法将渤海某油田稠油分离为沥青质、胶质、剩余分三个组分,含量分别为5.45%、26.5%、57.13%。通过红外光谱、元素分析和高分辨质谱分析了三组分的分子组成,采用界面张力仪、界面黏弹性仪测定了各组分与模拟水间的界面特性。研究结果表明,沥青质、胶质中含有大量酸性化合物,其中沥青质中酸性化合物的相对分子量高、缩合度高且富集多杂原子化合物。0.55%沥青质、5%胶质、5%剩余分模拟油与模拟水间界面张力分别为11.5、20、28 mN/m,说明酸性化合物是原油中主要活性物质,且多杂原子酸性化合物的界面活性更强。原油三组分模拟油的剪切黏度随剪切速率增加而下降,在剪切速率为0.02~0.4 rad/s时,原油三组分/模拟水界面剪切黏度排序为沥青质胶质剩余分,说明各组分形成的界面膜具有明显的结构特性,沥青质尤为明显。原油与乙醇胺溶液能形成稳定的W/O型乳状液,一周后仍无水相析出;除去原油中沥青质后,乳状液稳定性明显变差,11 h后油水完全分层;除去沥青质、胶质后,不能产生乳化现象,说明沥青质、胶质是渤海某油田稠油乳化的活性组分。     

孤岛聚合物驱原油沥青质乳化能力研究

沥青质是原油乳化的活性组分，研究沥青质对乳状液稳定性的影响，有助于明确聚驱采油污水含油过高的原因。从孤岛原油中分离正戊烷和正庚烷沥青质，运用红外光谱分析了其官能团差异，通过考察模拟地层水、聚合物和粘土对2种沥青质的乳化和界面张力性质的影响。结果表明，模拟地层水使正戊烷沥青质的乳化能力减弱。使正庚烷沥青质乳化能力增强；随着聚合物浓度增大，乳化能力增强，聚合物浓度在500mg／L时，界面张力最大；粘土浓度小于200mg／L时。对乳状液具有破乳作用，大于200mg／L时，则随粘土浓度增加，乳化能力增强。粘土浓度在300mg／L左右。界面张力最小。     

大庆原油与碱作用机理研究

 采用四组分分离法将大庆原油分离为饱和分、芳香分、胶质和沥青质，并用醇碱萃取法提取原油中的酸Ⅰ组分和酸Ⅱ组分。分别考察了各组分模拟油与水及碱体系的界面张力、界面剪切黏度，以及模拟油与碱长时间反应所形成的乳状液稳定性。结果表明，大庆原油中能降低油-水界面张力的主要活性组分是与碱反应较快的酸；对模拟油与碱体系形成的W/O型乳状液起稳定作用的主要组分是其中与碱反应较慢的、支链较多的大分子酸及酯类。大庆原油饱和分中存在着与碱发生慢反应的酯类。原油、原油组分模拟油与 碱反应初期，易形成O/W型乳状液，反应后期乳状液由O/W型向W/O型转变。醇碱萃取法只能萃取出与碱发生快速反应的酸组分，而不能将与碱反应较慢的相对分子质量较大的酸或酯类萃取出来。     

水包稠油乳状液稳定性研究：Ⅲ．稠油官能团组全与极性组分的油—水界面张力考察

从稠油官能团组分与极性组分油－水界面张力的角度,研究了稠油各组分的界面活性及其在水包油型乳状液中的作用机理和影响因素。测定了官能团四组分以及极性四组分的油－水界面张力,考察了组分浓度,水相pH值,温度,盐度等因素对油－水界面张力的影响。结果表明,稠油极性四组分的甲苯溶液－水的界面张力大小顺序为：饱和分＞芳香分＞胶质＞沥青质;官能团四组分的顺序为：中性分＞碱性分＞酸性分和两性分。酸性分,两性分及沥青质均具有低界面张力的特性,尤其在碱性（qH=11-12)条件下,界面张力很低,是稠油中主要的界面活性组分。碱性条件下更有利于O／W型超稠油乳状液的稳定。官能团组分更能揭示稠油中活性组分的内在本质。     

稠油中沥青质在碱水体系中乳化性能的研究

考察了我国两个稠油区(辽河和克拉玛依九区)遘选的稠油中沥青质在碱水体系中的乳化性能。结果表明，所研究的稠油中沥青质都含有乳化活性组分，它与碱液间均形成低界面张力，有利于碱水驱油。     

原油中沥青质在碱水驱油中乳化性能的研究

研究了胜利油田孤岛稠油及胜坨高凝油中沥青质在碱水驱油方法中的乳化性能。结果表明，所研究的原油中的沥青质均含有乳化活性组分，它与碱液间均能形成低界面张力，有利于碱水驱油。     

一种超稠油模拟油的油水界面扩张黏弹性研究

采用三组分分离法,从一种超稠油中分离出胶质、沥青质和抽余油,配制成不同浓度的模拟油。用OCA20界面张力仪/界面黏弹性仪考察了该种超稠油模拟油的动态界面扩张模量随扩张频率和活性组分浓度的变化规律,研究了从超稠油中分离出的胶质、沥青质和抽余油对模拟油油水界面张力及界面扩张性质的影响。结果表明,当各组分在模拟油中的浓度相同时,抽余油的界面张力最小,胶质的最大,沥青质的居中;含有不同活性组分模拟油的动态界面扩张模量均随扩张频率的升高而增大,胶质模拟油的动态界面扩张模量随活性组分浓度的增大而增大,而沥青质、抽余油模拟油的却先增加后降低;当活性组分浓度为1～4 g/L时,模拟油界面扩张模量的大小顺序为:沥青质胶质抽余油。     

Effect of Alkali on Daqing Crude Oil/Water Interfacial Properties

Alkaline-surfactant-polymer(ASP)flooding using sodium hydroxide as the alkali component to enhance oil recovery in Daqing Oilfield,northeast China has been successful,but there are new problems in the treatment of produced crude.The alkali added forms stable water-in-crude oil emulsion,hence de-emulsification process is necessary to separate oil and water.The problems in enhanced oil recovery with ASP flooding were investigated in laboratory by using fractions of Daqing crude oil.The oil was separated into aliphatics,aromatics,resin and asphaltene fractions.These fractions were then mixed with an additive-free jet fuel to form model oils.The interfacial properties,such as interfacial tension and interfacial pressure of the systems were also measured,which together with the molecular parameters of the fractions were all used to investigate the problems in the enhanced oil recovery. In our work,it was found that sodium hydroxide solution reacts with the acidic hydrogen in the fractions of crude oil and forms soap-like interfacially active components,which accumulate at the crude oil-water interface.     

Influence of surfactants used in surfactant-polymer flooding on the stability of Gudong crude oil emulsion

The influences of an anionic-nonionic composite surfactant and petroleum sulfonate, used in surfactant-polymer flooding in Shengli Gudong oilfield, East China, on the interfacial properties of Gudong crude model oil and synthetic formation water was studied by measuring interfacial tension, interfacial viscoelasticity and Zeta potential. The influence of the surfactants on the stability of Gudong water-in-oil (W/O) and oil-in-water (O/W) emulsions was evaluated by separating water from the W/O emulsion and residual oil in the aqueous phase of the O/W emulsion respectively. The results showed that the two kinds of surfactants, namely anionic-nonionic composite surfactant and petroleum sulfonate, are both able to decrease the interfacial tension between the oil phase and the aqueous phase and increase the surface potential of the oil droplets dispersed in the O/W emulsion, which can enhance the stability of the W/O and O/W crude oil emulsions. Compared with petroleum sulfonate, the anionic-nonionic composite surfactant is more interfacially active and able to enhance the strength of the interfacial film between oil and water, hence enhance the stability of the W/O and O/W emulsions more effectively.     

原油复配破乳剂的配方设计

研究了水相pH值、非离子破乳剂和助剂对沙轻原油、阿曼原油、杰诺原油、胜利原油乳液稳定性的影响 ,考察了破乳剂与助剂的协同效应。结果表明 :沙轻原油在水相 pH =6～ 7时乳液的稳定性最差 ;破乳剂通过降低界面张力和使沥青质胶团向油相解缔而破坏乳液的稳定性 ;有机小分子助剂改变界面极性环境或增加芳香度使沥青质增溶而破坏乳液的稳定性 ,它们与破乳剂有很好的协同效应     

ASP体系与大庆原油的乳化作用及影响因素

ASP三元复合体系与原油之间的乳化作用与该体系提高采收率以及采出液分离的效果直接相关.通过建立的ASP三元复合体系与原油乳化能力的评价方法,给出了ASP三元组分对乳化作用的影响;并系统评价了作用力和作用方式、油水比、ASP三元组分的类型及质量分数等因素对乳状液的类型和稳定性的影响.碱在乳化过程中起到非常重要的作用,高质量分数的碱有利于乳化形成,碱的强度直接影响形成乳状液的类型和稳定性,而水溶性聚合物可通过提高水相粘度和油膜或水膜的强度而增强乳状液的稳定性.     

Effects of Different Heavy Crude Oil Fractions on the Stability of Oil-in-water Emulsions — the film properties of heavy crude functional components and water system

A series of π-A isotherms are drawn to study the film properties of the components with Langmuir-Blodgett technique. The effects of the aromaticity of spread solvents and pH value on the air/water film formed by the components are investigated. Acid fraction and asphaltene can form stable two-dimensional insoluble films on an air/water surface.The surface film pressure of acid fraction and asphaltene is higher and more stable than that of the other fractions. The surface film pressure of the fraction increases evidently under the basic condition (pH=12). The results show that the interfaciai activity of acid fraction and asphaltene is superior to that of the other fractions and the basic condition is favorable to the stability of the O/W emulsion.     

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%。     

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.     

Characterization of the isolated wetting crude oil components with infrared spectroscopy

To improve the understanding of wettability, especially the influence of different crude oil colloids, wetting experiments on quartz sand and kaolin were performed with an asphaltene rich oil. A two-step procedure was developed to investigate the wetting behavior. In the first step, those crude oil components were extracted, which preferentially wet solid surfaces. The extracted crude oil components were characterized in a second step. The composition of the fractions extracted with different solvents are different. The acetone fractions extracted from quartz sand are rich in compounds containing nitrogen, whereas the compounds containing sulphur predominate in the chloroform fraction extracted from quartz sand. IR spectroscopy of the extracted fractions shows that carbonyl compounds are abundant in the methanol/chloroform and acetone/chloroform fractions extracted from quartz sand. The chloroform fraction is poor in carbonyl group-containing compounds. In agreement with elemental analysis, a strong signal for C–N groups in the IR spectra is found for acetone/chloroform and methanol/chloroform fractions, extracted from the quartz sand system. On the other hand, a significant, strong IR-peak representing S=O containing components is observed in the acetone and acetone/chloroform fractions, extracted from quartz sand.     

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

ABSTRACT

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.