The role of CO2 and ion type in the dynamic interfacial tension of acidic crude oil/carbonated brine

The e ects of CO2 and salt type on the interfacial tension(IFT) between crude oil and carbonated brine(CB) have not been fully understood. This study focuses on measuring the dynamic IFT between acidic crude oil with a total acid number of 1.5 mg KOH/g and fully CO2-saturated aqueous solutions consisting of 15,000 ppm of KCl, NaCl, CaCl2 and MgCl2 at 30 °C and a wide range of pressures(500–4000 psi). The results of IFT measurements showed that solvation of CO2 into all the studied aqueous solutions led to an increase in IFT of acidic crude oil(i.e., comparison of IFT of crude oil/CB and crude oil/brine), while no significant e ect was observed for pressure. In contrast, the obtained results of studied salts indicated a positive e ect on the IFT reduction of acidic crude oil/carbonated water(CW)(i.e., comparison of IFT of crude oil/CB and crude oil/CW).

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 interracial 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.

Effect of water salinity on oil/brine interfacial behaviour during low salinity waterflooding: A mechanistic study

In recent years,controlling the salinity and composition of the injected water has become an emerging enhanced oil recovery(EOR)technique,often described as low salinity(LS)waterflooding.This work is done with the intention to contribute to the ongoing discussions about LS waterflooding mechanism(s).For this purpose,a series of different experiments were conducted.At first,the effect of salinity on the interfacial tension(IFT)and the contact angle was evaluated with a crude oil sample.Then to achieve more accurate results in observing oil/water interface,similar IFT experiments were also carried out on a synthetic oil containing asphaltenes.Thereafter,microscopic visualization using glass micromodel was performed on the interface of the synthetic oil sample and brines.Four brine solutions including Sea Water(SW),it's dilutions and formation water(FW)were used for various experiments.Finally,to investigate the presented mechanism by other authors,a series of Environmental Scanning Electron Microscopy(ESEM)analysis on the synthetic oil was carried out to understand better the phase behaviour after contacting both synthetic oil and water phases from the micromodel experiment.Based on the existing mechanism,there exists an optimal concentration beyond which dilution is no longer an effective process.

An experimental and numerical study of chemically enhanced water alternating gas injection

In this work, an experimental study combined with numerical simulation was conducted to investigate the potential of chemically enhanced water alternating gas （CWAG） injection as a new enhanced oil recovery method. The unique feature of this new method is that it uses alkaline, surfactant, and polymer additives as a chemical slug which is injected during the water alternating gas （WAG） process to reduce the interfacial tension （IFT） and simultaneously improve the mobility ratio. In essence, the proposed CWAG process involves a combination of chemical flooding and immiscible carbon dioxide （CO2） injection and helps in IFT reduction, water blocking reduction, mobility control, oil swelling, and oil viscosity reduction due to CO2 dissolution. Its performance was compared with the conventional immiscible water alter- nating gas （I-WAG） flooding. Oil recovery utilizing CWAG was better by 26 % of the remaining oil in place after waterflooding compared to the recovery using WAG conducted under similar conditions. The coreflood data （cumulative oil and water production） were history mat- ched via a commercial simulator by adjusting the relative permeability curves and assigning the values of the rock and fluid properties such as porosity, permeability, and the experimentally determined IFT data. History matching ofthe coreflood model helped us optimize the experiments and was useful in determining the importance of the parameters influencing sweep efficiency in the CWAG process. The effectiveness of the CWAG process in pro- viding enhancement of displacement efficiency is evident in the oil recovery and pressure response observed in the coreflood. The results of sensitivity analysis on CWAG slug patterns show that the alkaline-surfactant-polymer injection is more beneficial after CO2 slug injection due to oil swelling and viscosity reduction. The CO2 slug size analysis shows that there is an optimum CO2 slug size, around 25 % pore volume which leads to a maximum oil recovery in the CWAG process. This study shows that the ultralow IFT system, i.e., IFT equaling 10 2 or 10 3 mN/ m, is a very important parameter in CWAG process since the water blocking effect can be minimized.

表面活性剂对水驱普通稠油油藏的乳化驱油机理

为了研究乳化降黏驱油剂对不同渗透率的水驱普通稠油油藏的驱油效率和孔隙尺度增效机理,选取了烷基酚聚氧乙烯醚(J1)、α-烯基磺酸盐类表面活性剂(J2)、十二烷基羟磺基甜菜碱(J3)、J3与烷基酚聚氧乙烯醚羧酸盐复配表面活性剂(J4)作为驱油剂,开展了4种驱油剂一维驱油和微观驱油模拟实验,明确了乳化降黏驱油剂在孔隙尺度的致效机理。结果表明,降低界面张力对提高驱油效率的作用大于提高乳化降黏率。在油藏条件下,乳化降黏驱油剂需要依靠乳化降黏和降低界面张力的协同增效作用,才能大幅提高驱油效率。乳化降黏驱油剂的乳化能力越强、油水界面张力越低,驱油效率增幅越大。当化学剂乳化降黏率达到95%时,油水界面张力从10^(-1)mN/m每降低1个数量级,化学剂在高渗透和低渗透岩心中的驱油效率依次提高约10.0%和7.8%。乳化降黏驱油剂注入初期通过降低界面张力,使得高渗透岩心和低渗透岩心中的驱替压力分别为水驱注入压力的1/2和1/3,从而提高注入能力。注入后期大块的原油被乳化形成大量不同尺寸的油滴,增强原油流动性,提高驱油效率。乳化形成的界面相对稳定的稠油油滴,能暂堵岩石的喉道和大块稠油与岩石颗粒形成的通道。油滴的暂堵叠加效应,使高渗透和低渗透岩心的驱替压差分别为水驱压差的5.2倍和32.3倍,大幅提高了注入压力,从而扩大平面波及面积。降黏驱油剂驱油实现了提高驱油效率的同时扩大波及范围。研究结果为水驱稠油开发用驱油剂的研发提供参考,为大幅提高水驱普通稠油采收率奠定基础。

The Colored Oil Property Effect on Switching Behavior of Electro-Fluidic Display

The switchable oil layer driven by electrowetting gives visible color and light valve control, which is the basis of Electro-Fluidic Displays. The colored oil’s property is a key factor that influences the Electro-Fluidic Displays switching behavior. A purple oil was formulated by the oil-soluble purple dye in decane in this study. The dye molecule itself is nonpolar and it doesn’t dissolve in water. The concentration of colored oil influenced the oil/water interfacial tension and oil viscosity. The relationship of EFD switching behavior with oil/water interfacial tension, oil viscosity, and oil conductivity has been systematically investigated. The oil/water interfacial tension decreased with increasing oil concentration, in the meanwhile, the conductivity increased. Oil conductivity was one of the key factors that influenced the Electro-Fluidic Displays optical property. We found for the first time that at the lower oil concentration (2% - 10%), the interfacial tension plays a main role effect on the rupture voltage and response time, but as the conductivity of higher concentration of colored oil increased (at 20%), the rupture voltage-controlled both by conductivity and interfacial tension.

应用OP-13复配型表面活性剂降黏实验研究

研究了以乳化剂OP-13作为主剂,与不同种类的阴离子和碱复配的三元复配体系对稠油的乳化降黏性能。结果表明,阴离子表面活性剂中质量分数为0.5%的SAS60与质量分数为0.6%的OP-13复配后,降黏效果最优,降黏率96.3%,分水率38%。三元复配体系中,OP-13、SAS60、叔丁醇钠以质量比6∶5∶3进行复配时,降黏性能最好,降黏率98.3%,分水率为1%。

水包油乳状液稳定性影响因素分析研究综述

管道运输是油品运输的重要方式之一,所以稠油乳状液在运输过程中的稳定性对运输效率起到决定性作用。不同类型的表面活性剂、界面张力、油水比、乳化温度、分散相粒径、化学添加剂、界面电荷等对稠油乳状液稳定性有着不同的影响,而影响水包油乳状液稳定性的主要因素是稠油乳状液分散性粒径的大小、界面张力和油水界面膜的性质。分析了平均粒径、界面张力和油水界面膜性质对水包油型稠油乳状液的稳定性影响,探究了使其稳定的机理和影响平均粒径、界面张力、油水界面膜性质的因素,并对水包油乳状液稳定性研究的发展前景进行展望。

纳米颗粒间相互作用对油-水界面张力的影响机制

为了研究油-水界面上纳米颗粒的动态吸附过程及其对界面张力的影响,采用耗散粒子动力学模拟方法,建立纳米颗粒在油-水界面物理模型,研究单颗粒的吸附动力学过程及多颗粒相互作用对界面张力的影响机制。结果表明:单颗粒在油-水界面的吸附分为自由扩散、界面吸附、动态平衡3个阶段;单颗粒吸附过程自由能变化远大于颗粒的动能,颗粒吸附可自发、快速进行,且吸附后能稳定在界面上;多颗粒间的相互作用力随颗粒间距离的增大而振荡衰减,这是由颗粒间的溶剂粒子所产生的溶剂化效应所致;当颗粒间相互作用为引力时,界面张力增大,当颗粒间相互作用为斥力时,界面张力减小。

新型表面活性剂提升油气开发采收率的影响研究

为了提升油气开发采收率,通常会使用表面活性剂。但是由于单一表面活性剂无法实现超低表面张力(IFT)和强亲水条件,因此传统的表面活性剂驱的油气开发采收率受到了影响。为了解决这些问题,通过表面活性剂混合物来实现提高石油采收率是一种较为可行的方案。检验了新型复合表面活性剂作为提高石油采收率的潜在手段的方案,结果表明,与单独的表面活性剂溶液相比,复合表面活性剂对油水表面张力和润湿性变化具有更显著的影响。使用复合表面活性剂系统可获得超低的表面张力(约0.006 mN·m^(-1)),因此研究认为此种新型复合表面活性剂有效并可投入油田开发。

油田深度调剖化学剂驱油效率与机理

随着石油资源的日益紧张,提高油田开采效率成了石油行业面临的主要挑战。选用3种不同的化学剂(PAM、SDBS、PAA)并通过测定岩心渗透率和油水界面张力进行驱油效率实验。实验结果显示,PAA在提高岩石渗透率方面表现最为突出,从130.14 m D增加到212.43 m D,增幅为63.2%,而SDBS则在降低油水界面张力方面表现最佳,从38.92 m N·m^(-1)降至21.00 m N·m^(-1),降低了46.2%。此外,在中温(40℃)和中压(20 MPa)以及适中的注入流量(100 L·min^(-1))下,驱油效率达到最优。化学剂在改变岩石孔隙结构及降低油水界面张力方面的作用,共同促进了油水流动性的提升,从而显著增强了整体的驱油效果。研究结果对于指导实际油田作业中化学剂的选择和应用具有重要的参考价值,为油田开发提供了新的视角和方法。

高效深度调剖化学剂在提高采收率中的应用及机理研究

通过高效液相色谱分析、界面张力仪测量、岩心驱替实验和扫描电子显微镜观察等实验方法,探究了高效深度调剖化学剂在提高采收率中的应用及其作用机理。结果表明:该化学剂主要由交联聚合物(58.6%)、表面活性剂(29.5%)和纳米粒子(11.9%)组成,具有良好的流变性能和热稳定性。化学剂在25℃时的黏度为121.6 mPa·s,随温度升高而降低,但在100℃时仍保持58.3 mPa·s的黏度;化学剂能显著降低油水界面张力,从32.6 mN·m^(-1)降至9.6 mN·m^(-1);在岩心驱替实验中,使用该化学剂后的额外采收率达到了19.2%,总采收率提高到47.8%,最佳的注入参数组合为化学剂质量分数0.5%,注入速率0.5 mL·min^(-1),注入量1.0 PV。机理分析表明,该化学剂通过降低油水界面张力、改善油藏渗透性、调整流动阻力和改变孔隙结构等多重机制,有效提高了采收率。该研究为油田的高效开发提供了新的技术支持,对于提高油田采收率具有重要的理论意义和应用价值。

钻井液用稠油降黏剂的研制与性能评价

稠油中含有胶质、沥青质等物质,使稠油与钻井液滤液形成W/O型乳状液,增大了稠油的开采难点。针对上述技术难题,以苯二酚、环氧乙烷、环氧丙烷、氯磺酸为原料制备一种水基钻井液用稠油降黏剂JN-A,应用于水基钻井液中,评价稠油降黏剂JN-A对稠油黏度的影响。结果表明:水基钻井液的滤液与稠油形成乳状液,使稠油的黏度上升至983.4 mPa·s,而3%稠油降黏剂JN-A使稠油黏度降低至75.1 mPa·s,其降黏率高达91.97%,表现出优异的降黏效果。稠油降黏剂JN-A使滤液-稠油界面张力降低至0.51mN·m^(-1),并降低储层岩心孔喉对稠油的黏附性和稠油在储层孔喉中的流动阻力,有利于稠油油藏的开采。

稠油油藏化学驱采收率的影响因素

采用烷基聚氧丙烯醚硫酸盐和羧基甜菜碱两类两性表面活性剂与碱复配构建具有不同界面张力特点的驱油体系,通过驱油试验评价不同体系对桩西稠油采收率的影响,采用微观驱替试验研究不同体系提高采收率的机制。结果表明:界面张力与采收率没有明显的对应关系;碱通过维持油、水、固三相接触点亲油性和降低油水界面张力,减弱驱替介质沿油与岩石之间的渗入,增强驱替介质从原油中心的突进和分散,提高驱替压力和波及体积;相比于碱和原油反应产生的表面活性剂,外加的表面活性剂亲水性较强,会增强固体表面的亲水性,导致驱油剂沿孔隙壁面突进;表面活性剂-碱体系与原油形成的细分散水包油型乳状液加剧了驱油剂的窜进,不利于提高波及系数;对于稠油油藏,化学驱体系的波及系数是提高采收率的关键因素。

阴离子双子表面活性剂的油水界面张力研究

为探究GA系列新型阴离子双子表面活性剂的油水界面活性及提高油层原油采收率的可行性,以模拟地层水和东河塘稀油,在45℃条件下,利用旋转液滴法测试了不同分子结构阴离子双子表面活性剂与稀油间的界面张力,并以GA12-4-12为对象,测试了其在不同浓度时的动态界面张力,考察了其与非离子表面活性剂ANT的复配性能。结果表明:连接基长度及碳链长度越长,油水界面张力越低;随GA12-4-12浓度增加,界面张力先降后升,0.3%时油水界面张力仅0.00885mN/m,但时间稳定性变差;GA12-4-12与ANT复配协同效果明显,复配比为4∶1时0.1%(GA12-4-12+ANT)加量可使油水界面张力达超低(0.00884mN/m),明显降低了GA12-4-12用量。可见GA12-4-12与ANT复配体系具有低剂量下提高原油采收率的性能,建议用该配方进行提高原油水驱采收率试验研究工作。

水包稠油乳状液稳定性研究 Ⅲ. 稠油官能团组分与极性组分的油-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 (pH =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。

胜利油田高温高盐稠油油藏复合驱技术

为提高胜利油田孤岛油田东区油藏化学驱油体系的耐温性、抗盐性、增黏性,研制了新型二元复合驱油体系。根据聚合物驱水油黏度比与提高采收率的关系,确定了聚合物的合理黏度,利用动态界面张力分析,研究了驱油体系各组分之间的相互作用。实验结果表明:油藏条件下分子质量为22×10~6的超高分子质量聚丙烯酰胺可满足驱油要求;石油磺酸盐(SLPS)与烷醇酰胺类非离子表面活性剂(GD-1)复配能大幅度提高体系的界面活性和抗钙能力;高效二元复合驱配方为0.18%聚合物+0.2%SLPS+0.2%GD-1,室内提高采收率17.4个百分点。孤岛东区Ng3-4二元复合驱先导试验于2011年实施,试验后综合含水率从94.7%降至80.9%,日产油由279 t/d增至778 t/d,截至2016年8月,试验区已累计增油65×10~4t,提高采收率6.0个百分点,预测可提高采收率11.3个百分点。研发的新型二元复合驱油体系可满足胜利油田高温、高盐稠油油藏开发的需要,先导试验的成功为同类油藏大幅度提高采收率研究提供了借鉴。

稠油驱油体系乳化能力和界面张力对驱油效果的影响

提出了定量表示表面活性剂体系乳化稠油难易程度的参数"乳化最小转速"。在55℃下测定了7种不同驱油剂与桩106-15-X18普通稠油组成的体系的油-水动态界面张力和乳化最小转速,并对其中5种驱油剂-稠油体系进行了室内驱油实验。结果表明,驱油剂-稠油体系乳化最小转速与其油-水动态界面张力没有对应性,而且,驱油剂-稠油体系的油-水动态界面张力与其采收率也没有一定的规律性,但乳化最小转速与采收率有较好的对应关系,乳化最小转速的体系采收率高,即乳化能力高的体系驱油效果好,乳化能力低的体系驱油效果差。

超低界面张力强化泡沫体系稠油驱研究

针对孤东六区稠油油藏条件,研究得到既能在不含碱的条件下与原油形成超低界面张力,又能形成稳定泡沫的超低界面张力强化泡沫体系。其配方为:3.0 g/L石油磺酸盐+5.0 g/L HEDP-Na4+0.6 g/LⅠ型两亲聚合物,气体为氮气。该体系具有较好的泡沫性能和乳化降黏性能,并且两亲聚合物能够改善泡沫的稳定性和体系对原油的乳化效果。超低界面张力强化泡沫体系对孤东六区稠油具有较好的驱替性能,原油采收率能够在水驱的基础上提高37.9%,总采收率达到65.7%,所注入体系能在较长时间里发挥调剖和驱油效果。

永平油田稠油自发乳化降粘剂的筛选及驱油效果评价

针对永平油田稠油粘度大、油层厚度薄、原始含油饱和度低及热采投产后产油量低的现状,筛选出一种能使稠油在地层中发生自发乳化的降粘剂,使稠油以较低粘度的乳状液被采出,从而提高稠油的采收率。针对不同乳化降粘剂对永平油田稠油的乳化效果评价结果表明,自发乳化降粘剂NS在质量分数为2%、温度为45℃的条件下,可将油水界面张力降至10-3mN/m数量级以下,并可完全自发乳化等体积的永平油田稠油,降粘率达99.74%。NS自发乳化驱油实验结果表明,经过后续水驱后,自发乳化驱的采收率在水驱基础上提高了38.18%。