石油羧酸盐及其复配体系中混合胶束对界面活性的影响

为揭示石油羧酸盐界面活性的结构成因,深入研究石油羧酸盐和磺酸盐的复配规律,选取了平均碳数分别为23.16、26.01、28.70的大庆原油馏分作原料制备石油羧酸盐,优选了一种平均碳数和油酸钠碳数相近的石油羧酸盐并将其界面活性与油酸钠进行了比较研究。此外,针对矿化度较高(矿化度11948.4 mg/L)、石油羧酸盐可以在低碱甚至无碱条件下单独达到超低界面张力的红岗油田,考察了石油羧酸盐和石油磺酸盐形成的混合胶束对复配体系界面活性的影响。研究结果表明,平均碳数和油酸钠碳数相近的石油羧酸盐的界面活性远优于油酸钠,其原因是石油羧酸盐由不同碳链长度的分子组成,由于亲水亲油性(HLB值)的差别,长链分子和短链分子在油水界面上插入深度不同,混合胶束的极性基团之间的斥力较单一分子组成的油酸钠极性基团间斥力小,分子间排列较紧密,界面吸附量较大。石油羧酸盐和磺酸盐的复配体系在矿化度较高的红岗油田具有很好的复配效果,石油羧酸盐和磺酸盐复配体系的界面活性比单剂好,达到初始界面张力的时间明显比单剂的短。石油羧酸盐单剂体系及复配体系中的混合胶束均使界面活性显著提高。     

驱油聚合物对甜菜碱降低界面张力的影响

为揭示化学驱体系中聚合物以及油相中活性物质对甜菜碱降低界面张力作用的影响规律,研究了部分水解聚丙烯酰胺和疏水缔合聚合物对甜菜碱溶液与正癸烷间动态界面张力的影响,考察了正癸烷中加入油酸对甜菜碱及甜菜碱与聚合物二元复配体系界面张力的影响。研究结果表明,甜菜碱类表面活性剂的亲水基团尺寸大于疏水基团,相应体系与正构烷烃间的界面张力较高;油相中的油酸与甜菜碱混合吸附,能明显降低界面张力。部分水解聚丙烯酰胺通过混合吸附使得甜菜碱溶液与正癸烷的界面张力总体上呈升高趋势;而疏水缔合聚合物与甜菜碱形成界面混合聚集体,造成界面张力升高。在油酸存在的条件下,两类聚合物对模拟油与甜菜碱间界面张力的影响趋势与正癸烷相近。     

复配表面活性剂对三元复合体系界面张力影响研究

研究了石油羧酸盐与不同磺酸盐的复配体系的界面活性,测定了复配表面活性剂在大庆油砂上的吸附量。结果表明,复配体系的界面活性优于单一的磺酸盐体系。将少量磺酸盐与石油羧酸盐复配,可使体系达到超低界面张力,碱度范围拓宽,初始界面张力变低。复配表面活性荆吸附过程中羧酸盐起到了牺牲剂作用,降低了磺酸盐的吸附损失,复配体系的这些特点对提高驱油效率很有利。     

全氟壬烯氧基苯磺酸钠与烷醇酰胺复配体系的研究与应用

研究了全氟壬烯氧基苯磺酸钠(OBS)与烷醇酰胺(CDEA)按不同比例复配后体系的表面张力、油水界面张力的变化情况,并对复配体系的耐温性能进行评价,同时考察了复配体系对压裂液的影响。实验结果表明:OBS与CDEA复配后具有协同效应,能降低体系的表、界面张力;OBS/CDEA复配体系经130℃,6h热处理后表、界面张力变化小,具有良好的热稳定性能;0.01%OBS+0.1%CDEA的加入能降低了压裂液破胶液的表、界面张力,提高了压裂液的返排率,可将此复配体系应用压裂液助排中使用。     

两种石油酸对二元驱油体系关键性能的影响*

为明确原油中石油酸对复合驱油体系界面张力和乳化性能的作用规律,以复合驱试验区原油为原料分离出两种石油酸和除酸油,分析了两种石油酸的结构和碳数分布,研究了其对二元驱油体系动态界面张力和乳状液稳定性的影响。结果表明,1#石油酸和2#石油酸的相对分子质量分别为242和312,其碳数分布分别为10～15和10～25。700 mg/L的2#石油酸可使油水平衡界面张力(IFT_(eq))降为0.021 mN/m,而同浓度的1#石油酸仅能使IFT_(eq)降为0.095 mN/m。混合酸对降低界面张力有正向协同作用,两种石油酸复配可使二元驱油体系的油水界面张力达到超低。含酸体系的乳液稳定性与油水动态界面张力相关联,含2#石油酸的油水乳状液体系的IFTeq较低,乳液的最终稳定性较高。通过对二元驱油体系性能与原料物性参数的分析,指出可以提高原料油石油酸含量来合成二元驱用磺酸盐,以增加二元驱油体系的乳化性能,获得较好的降低油水界面张力效果。图9表3参12     

磺酸盐与磺酸盐表面活性剂协同作用研究

为获得具有性能优良的表面活性剂,研究了磺酸盐与磺酸盐表面活性剂在降低油水界面张力方面的协同作用。选取了十二烷基苯磺酸钠(C12ΦS)与4-(7'-十四烷基)苯磺酸钠(7C14ΦS)、4-(8'-十八烷基)苯磺酸钠(8C18ΦS),绘制了磺酸盐及复配体系的烷烃扫描曲线,考察了表面活性剂的亲水亲油性能、复配比例对协同作用的影响及磺酸盐及复配体系降低原油界面张力的能力。证实了磺酸盐与磺酸盐复配协同作用源自亲水亲油性能的改善,亲油性磺酸盐8C18ΦS与亲水性磺酸盐C12ΦS、7C14ΦS复配,可以获得具有适中亲水亲油性能的复配体系,实现协同降低界面张力作用,通过适当的磺酸盐表面活性剂复配可使长庆油田原油与1%Na Cl水溶液的界面张力降低至超低值。     

孤东油田有机碱与原油相互作用界面张力变化规律

为了深入认识碱与原油之间的作用规律,对酸值较高的孤东油田原油进行了研究,通过提取石油酸,切分原油组分,考察了碱的类型、pH值对不同原油组分模拟油界面张力的影响.实验结果表明:有机碱和无机碱分别与孤东油田原油作用,界面张力变化规律不同,随着溶液pH值的升高,无机碱溶液使孤东油田原油界面张力下降至最低值后不再变化,而有机碱溶液使原油的界面张力先降低后升高,界面张力最低值对应的有机碱质量分数为1.0％;有机碱与原油酸性组分作用生成活性物质,可降低界面张力,使动态界面张力曲线呈“V”形或“U”形;有机碱与原油中的胶质、沥青质组分作用均可产生活性物质,初始界面张力最低,后逐渐升高;有机碱与原油中饱和分、芳香分之间没有相互作用.     

石油羧酸盐与烷基苯磺酸盐的复配效果及其结构成因

为揭示石油羧酸盐与烷基苯磺酸盐复配体系的性能特征,考察了石油羧酸盐和烷基苯磺酸盐形成的混合胶束(超分子结构)对复配体系界面活性的影响。结果表明,亲水亲油平衡值(HLB值)的差别使石油羧酸盐分子和烷基苯磺酸盐分子在油水界面上插入深度不同,由于距离拉开而减少了极性基团间的斥力,因而混合胶束排列得较紧密,界面吸附增加,界面活性比单剂好。此结构特点对复配体系界面活性的影响体现在:复配体系能在较宽的表面活性剂浓度及矿化度范围产生超低界面张力;在0.6%数1.2%弱碱(Na2CO3)下有优良的界面活性,避免了强碱(Na OH)对地层的伤害;达到超低界面张力所需表面活性剂浓度较低,可以降低驱油剂成本;在和油粒接触后可较快达到超低界面张力,对驱油过程有利。复配体系在强碱、弱碱、无碱情况下的界面活性均较好。和石油羧酸盐有良好协同效应的烷基苯磺酸盐应是直链分子结构,才能形成较紧密的混合胶束,具有较高的界面活性。     

羧基甜菜碱-烷醇酰胺复配体系界面张力研究

研究了以不同比例复配的羧基甜菜碱/烷醇酰胺体系与临盘原油的动态界面张力,筛选出了适用于临盘凝油的表面活性剂体系。结果表明,单一的烷醇酰胺或甜菜碱与临盘原油间的界面张力值达不到超低值;而两种活性剂以1∶1和2∶1进行复配时,具有明显的协同效应,在总浓度为0.005%～0.2%范围内,油水界面张力值可降低到10-4 mN/m数量级,且经过石英砂静态吸附后,复配体系具有较好的低界面张力性能,是一种具有现场应用价值的表面活性剂体系。     

有机碱三元复合驱油体系与胜利原油的协同作用

采用旋转滴法测定了胜利石油磺酸盐与不同区块原油的油水界面张力,考察了有机碱乙醇胺及聚合物对体系界面张力的影响,测定了复合驱体系的粘度。实验结果表明,乙醇胺和胜利石油磺酸盐之间存在降低油水界面张力的协同效应,在适宜的乙醇胺浓度条件下,界面上的石油酸、反应生成的石油酸皂和石油磺酸盐混合吸附,界面张力达到最低。聚合物对界面张力总体影响不大。有机碱三元复合驱体系的粘度变化不大。     

Effect of active species in crude oil on the interfacial tension behavior of alkali/synthetic surfactants/crude oil systems

The effect of active species present in crude oil on the interfacial tension （IFT） behavior of alkali/synthetic surfactants/crude oil systems was studied. The system consisted of heavy alkyl benzene sulfonate, sodium chloride, sodium hydrate and Daqing crude oil. Experimental results indicated that active species would diffuse from oil/aqueous interface to aqueous phase and finally an equilibrium could be reached in the system with increasing contact time. Moreover, the minimum IFT and equilibrium IFT values increased with increasing contact time and a linear relationship existed between dynamic IFT and f^-1/2 when IFT value approaching the minimum and after the minimum IFT was reached. This indicated that the dynamic IFT-time behavior was diffusion controlled. The oil and aqueous phases were analyzed by infrared （IR） spectroscopy. IR spectra of oil and aqueous phases illustrated that the content of active species in the oil phase decreased, but the content of active species in the aqueous phase increased after alkali reacted with crude oil. This indicated that the active species present in oil played an important role in reducing IFT.     

界面张力对相对渗透率曲线的影响

本文研究了界面张力对相对渗透率曲线的影响。为此进行了一系列非稳态驱替实验。实验是采用非胶结岩心和不同界面张力的流体体系进行的。 流体体系中,被驱动相采用的是模拟原油,驱动相分别是:地层水、表面活性剂溶液、下相微乳液和中相微孔液。研究结果表明:①界面张力对相对渗透率曲线有实质性影响。随着界面张力的降低,驱替相和被驱替相的相对渗透率曲线均升高。特别是在界面张力σ<10~(-2)mN/m时此影响更明显。②随着界面张力的降低原油采收率有明显的提高。     

胜利原油活性组分对原油-甜菜碱溶液体系油-水界面张力的影响

采用传统的柱色谱四组分分离方法（SARA）将胜利孤岛原油分离得到沥青质、饱和分、芳香分和胶质,采用碱醇液法萃取原油得到酸性组分。测定了正构烷烃、煤油以及原油活性组分模拟油与2种不同疏水结构的甜菜碱溶液组成的体系的油 水界面张力。结果表明,在原油活性组分模拟油 甜菜碱溶液体系中,直链甜菜碱由于疏水基团较小,与原油活性组分尤其是酸性组分和胶质发生正协同效应的混合吸附,使油 水界面上表面活性剂分子的含量增加,界面膜的排布更紧密,导致油 水界面张力降低;支链甜菜碱由于具有较大尺寸的疏水基团,煤油中少量的活性物质即可将油 水界面张力降至超低(<10-3 mN/m),而原油活性组分的加入,则使界面上表面活性剂分子的排布被破坏,削弱了界面膜原有的紧密性,导致油 水界面张力大幅度升高。     

石油羧酸盐和磺酸盐复配体系的界面活性

研究了用石油馏分液相氧化产物制得的石油羧酸盐与不同磺酸盐（ＯＲＳ－４１、Ｂ－１００、ＭＳ－４５等）的复配体系的界面活性。结果表明,复配体系的界面生优于单一的石油羧酸或磺酸盐体系。复配体系的这些特点对提高驱油效率很有利。     

用中和烃氧化产物制备高界面活性的驱油剂

为了用C_(22)和C_(26)直链和环烷烃的石油馏分油作原料制备适用于强化采油的活性剂,先将原料汽相氧化,再用碱液中和氧化产物。用红外光谱研究了氧化产物和中和产物的组成,发现前者含有羧酸,后者含有羧酸盐。得到的羧酸盐活性剂用于模拟油[由38.8%(体积)的异丙苯和61.2%(体积)的正癸烷组成],使油水间达到低于10~(-2)mN/cm的超低界面张力。实验表明,用氢氧化钠进行中和,比用其他的碱性物质(如硅酸钠、三聚磷酸钠、碳酸钠)更易得到界面活性高的活性剂溶液;当硅酸钠或三聚磷酸钠协同氢氧化钠一起与氧化产物反应时,所得活性剂的界面张力对电解质浓度的敏感程度比仅用氢氧化钠作处理剂时低,中和时的碱量会影响所得活性剂体系的界面张力。对于活性剂浓度不同的体系,若pH值相同则最佳含盐量也相同;若pH值高,则最佳含盐量低。当活性剂体系含有1000ppm的氯化钙时,仍具有良好的界面活性。在驱油试验中,浓度为1%的1个孔隙体积的活性剂溶液可采出42%的二次残油。     

Thermophysical interface properties of crude oil and aqueous solution containing sulfate anions: experimental and modeling approaches

Abstract

Sulfate anion is well-known for being one of the most active agents to be injected into the oil reservoirs and being capable of not only altering the interfacial properties of crude oil but also enhancing the water solution properties in oil recovery. In the current study, the effects of temperature and pressure were studied on interfacial tension (IFT) as well as the adsorption behavior of two different solutions containing sulfate anion using experimental measurements and modeling approaches. Although it was expected that IFT values of the studied systems might decrease as temperature increased due to the improvement in the molecule mobility and solubility of crude oil in water, which consequently might lead to the reduction in its free energy, the reverse trend was observed. The measured dynamic IFT values and adsorption behavior revealed that surface excess concentration of natural surfactants (Г_NS) can be considered as the most effective parameter on interpreting IFT behavior as a function of temperature.     

PRODUCING ULTRALOW INTERFACIAL TENSION AT THE OIL/WATER INTERFACE

In view of the world-wide shortage of petroleum and the fact that a large amount of residual oil will remain in the reservoir after the primary recovery and water flooding stages, the use of Enhanced Oil Recovery (EOR) methods to recover as much as possible of this residual oil has become increasingly important worldwide. The predominant and most promising EOR technique is the micellar-polymer flooding process which uses a surface active agent (a surfactant) to decrease interfacial tension and hence allows oil to freely move from its original location through the porous media. The purpose of this paper is to present an experimental study of the factors affecting the equilibrium interfacial tension (IFT) at the oil/water interface. A large number of experiments was conducted to study the variations of IFT as a function of many parameters including reservoir temperature, pressure, surfactant concentration, and salinity. An Arabian heavy crude oil was used in the analysis along with three different synthetic surfactants and two formation waters. The pendent drop technique enhanced by video imaging was employed for measuring IFT. It was found that for the ranges of variables considered in this study, IFT decreases with temperature and salinity, increases with pressure, and decreases exponentially with surfactant concentration.     

STUDYING THE INTERACTIONS BETWEEN AN ARABIAN HEAVY CRUDE OIL AND ALKALINE SOLUTIONS

An experimental study to examine the effectiveness of alkaline flooding for the recovery of an Arabian heavy crude oil is presented. The interfacial tension (IFT) behavior of crude oil/alkali systems over a wide range of parameters (pressure, temperature, alkali concentration and time) was studied. These alkaline reagents react with the acidic species in crude oil to form surface-active soaps in-situ. This leads to a lowering of interfacial tension (IFT) and subsequently the mobilization of residual oil. The equilibrium IFTs obtained through alkaline flooding are compared with the IFTs when a synthetic surfactant (dodecyl benzene sulfonic acid sodium salt) is used in EOR recovery. A mathematical model representing the complete chemistry of the transient process is also presented. The model consists of a set of differential equations describing reactions, diffusion, and adsorption at the oil/alkaline solution interface. The kinetic parameters in the model are obtained through a differential algebraic optimization technique. The concentration of the surface active species are related to the measured IFTs through an independent step that is based on isolating the surface active species formed by the reaction between the acids in the crude oil and the alkaline solution. A sensitivity analysis using the model is carried out to study the effect of surface potential and alkaline concentration on the transient interfacial tensions.     

界面张力特征对三元复合驱油效率影响的实验研究

分别采用了油水平衡界面张力和瞬时动态界面张力为1mN/m、0.1mN/m、0.01mN/m和0.001mN/m的4种体系进行了岩心驱油试验.结果表明,在大庆油田三元复合驱中,油水动态界面张力最低值是影响驱油效果的重要因素,而不是平衡界面张力.动态界面张力最低值达到0.01mN/m时,体系的驱油效果与界面张力平衡值达到0.001mN/m时基本相同.因此,可以大幅度降低三元复合体系中碱的用量,甚至可以不用碱.此外,还可以降低对表面活性剂的苛刻要求,扩大表面活性剂的种类和范围.     

PRODUCING ULTRALOW INTERFACIAL TENSION AT THE OIL/WATER INTERFACE

ABSTRACT

In view of the world-wide shortage of petroleum and the fact that a large amount of residual oil will remain in the reservoir after the primary recovery and water flooding stages, the use of Enhanced Oil Recovery (EOR) methods to recover as much as possible of this residual oil has become increasingly important worldwide. The predominant and most promising EOR technique is the micellar-polymer flooding process which uses a surface active agent (a surfactant) to decrease interfacial tension and hence allows oil to freely move from its original location through the porous media. The purpose of this paper is to present an experimental study of the factors affecting the equilibrium interfacial tension (IFT) at the oil/water interface. A large number of experiments was conducted to study the variations of IFT as a function of many parameters including reservoir temperature, pressure, surfactant concentration, and salinity. An Arabian heavy crude oil was used in the analysis along with three different synthetic surfactants and two formation waters. The pendent drop technique enhanced by video imaging was employed for measuring IFT. It was found that for the ranges of variables considered in this study, IFT decreases with temperature and salinity, increases with pressure, and decreases exponentially with surfactant concentration.