微乳液泡沫驱油技术原理、挑战和研究进展

微乳液驱和泡沫驱是强化采油领域中的两个重要技术。前者利用表面活性剂形成油-水微乳液提高增溶能力,降低油水界面张力和毛细管阻力,从而提高驱替效率和微观采收率;后者利用泡沫剂将气体稳定地分散在水相中,在油藏孔隙中形成泡沫,封堵优势通道和已驱替区域,从而扩大波及体积并提高宏观采收率。通过综述两个技术的国内外发展历史和研究进展,阐明了其优势和局限性。近年来提出的微乳液泡沫驱油技术,又称为低张力泡沫驱,其既可以保留两个独立技术的优势,又可以克服他们的缺点,最终同时提高微观和宏观采收率。但是在实际研究中,微乳液泡沫驱技术却面临理论和应用上的双重挑战。通过调查国内外相关研究进展,详细阐述了微乳液泡沫驱技术目前面临的挑战、研发思路和研究建议。     

泡沫驱提高采收率技术研究新进展

泡沫驱提高采收率技术研究新进展主要集中在:①气-液-固三相泡沫驱,包括纳米颗粒泡沫、膨润土泡沫和粉煤灰泡沫;②微泡沫驱;③自生气泡沫驱,包括自生CO_2泡沫和自生N_2泡沫;④泡沫复合驱,包括泡沫-凝胶深部调驱、冻胶泡沫强化封堵;⑤泡沫-物理法复合技术提高采收率,包括泡沫-振动波综合调驱、泡沫-热力采油。就以上技术展开综述,介绍了研究进展、作用机制和存在问题,并对下一步研究进行了展望。     

阴非离子复配微乳液体系优选及驱油效果

针对阴非离子表面活性剂复配微乳液体系优选,研究不同摩尔比情况下的界面张力和乳化率的大小,优选出复配表面活性剂合适的摩尔比。利用天然岩心微乳液驱油实验说明微乳液驱提高采收率的效果,现场数值模拟应用技术验证微乳液驱油实验的准确性。结果表明,优选出的最佳微乳液驱油体系是质量分数为4%,摩尔比3∶7的烷基酚聚氧乙烯醚与十二烷基磺酸钠,质量分数为2%的正丁醇,质量分数为0.8%的NaCl。与水驱相比,微乳液驱提高采收率增幅可达到13.06个百分点,采收率提高效果较为显著。现场数值模拟技术的应用结果表明,天然岩心的驱油实验的实验值与理论值相差不大,整体曲线拟合误差不超过3个百分点,具有较高的准确性。     

微泡沫提高采收率技术研究进展

通过广泛调研和分析,介绍了泡沫驱现状及存在的问题,总结了微泡沫的主要性质与驱油特性,介绍了目前常用的微泡沫生成方法,微泡沫国内外研究现状,讨论了微泡沫提高采收率技术走向现场应用需要研究解决的几个关键技术问题。     

微泡沫提高采收率技术研究进展

通过广泛调研和分析,介绍了泡沫驱现状及存在的问题,总结了微泡沫的主要性质与驱油特性,介绍了目前常用的微泡沫生成方法,微泡沫国内外研究现状,讨论了微泡沫提高采收率技术走向现场应用需要研究解决的几个关键技术问题。     

微乳液形成及相行为研究

微乳液作为一种表面活性剂浓溶液体系,在采油过程以其超低的界面张力、高的增溶能力及热力学稳定性等优点大幅度提高原油采收率从而受到人们的重视。本文主要研究微乳液的形成方式、微观结构、相行为特点和微乳液在三次采油过程中的主要作用。     

三元复合驱体系驱油剂的开发

用D相乳化法,由十二烷基苯磺酸钠与醇醚硫酸盐、多元醇、二甲苯等复配生产了新型微乳液驱油剂S99;并以之配制了三元复合驱体系。该体系的质量百分组成为:0.06%S99+1.5%氢氧化钠+0.15%聚合物+0.2%助剂。此复合驱体系可使油水张力降低到1.1×10-2mN/m,并进行了原油驱替实验,结果表明,可提高采油率13.82%,提高剩余油采收率27.8%。     

泡沫驱提高采收率的研究进展

本文介绍了国内外泡沫驱提高采收率技术的一些研究进展,主要包括氮气泡沫驱、二氧化碳泡沫驱和空气泡沫驱。综述了各种泡沫驱提高采收率的矿场应用现状和机理研究进展,并指出了泡沫驱的当前研究热点和未来发展方向。     

微乳液驱油技术强化石油采收率的研究进展

近几年我国对于石油能源的需求量越来越大，提升石油产量的方法也就受到了越来越多的重视，例如将微乳液驱油技术应用于石油采收工作之中，可以对油水界面表面张力起到有效的控制作用，同时降低含油岩层的湿润程度，也就有利于提升石油的采收率，所以，本文对微乳液驱油技术强化石油采收率的情况进行分析，以供参考。     

乳液流体在石油开发中的研究进展

乳液体系作为一种极具潜力的调驱体系和提高采收率手段,受到广泛的重视.相比于传统的表面活性剂制备的乳液体系,利用化学驱组分与纳米材料制备的乳状液通过润湿调控作用、贾敏效应以及降黏作用显著地提高了水驱后岩心的采收率.但是与传统乳液相比,新型的乳液驱油体系在界面性质特别是界面黏弹性方面存在显著的差异,而油水界面特性的改变都会显著地影响流体在多孔介质中的渗流规律以及微观孔隙尺度和宏观地层尺度下的压力响应特征.目前乳液体系在多孔介质中的渗流规律更多考虑其粒径与地层孔隙尺寸的匹配关系,并未充分考虑纳米材料对油水界面性质的影响.因此未来针对乳液体系的研究将更多侧重于纳米材料对乳液界面特性的影响和对其渗流规律的作用机制.     

Effect of oil viscosity on recovery processes in relation to foam flooding

Laboratory experiments were conducted to determine the effect of oil viscosity on the oil-recovery efficiency in porous media. The pure surfactants (i.e., sodium dodecyl sulfate and various alkyl alcohols) were selected to correlate the molecular and surface properties of foaming solutions with viscosity, and the recovery of oil. Oil-displacement efficiency was measured by water, surfactant-solution and foam-flooding processes, which included 2 types of foams (i.e., air foam and steam foam). A significant increase in heavy-oil recovery was observed by steam foam flooding compared with that by air foam flooding, whereas for light oils, the steam foam and air foam produced about the same oil recovery. An attempt was made to correlate the chain-length compatibility with the surface properties of the foaming agents and oil-recovery efficiency in porous media. For mixed foaming systems (C₁₂ SO₄ Na + C_n H_2n+1 OH), a minimum in surface tension, a maximum in surface viscosity, a minimum in bubble size and a maximum in oil recovery were observed when both components of the foaming system had the same chain length. These results were explained on the basis of thermal motions (i.e., vibrational, rotational and oscillational) and the molecular packing of surfactants at the gas-liquid interface. The effects of chain-length compatibility and the surface properties of mixed surfactants are relevant to the design of surfactant formulations for oil recovery under given reservoir conditions.     

空气泡沫驱驱油机理与实验研究

针对传统聚合物驱、三元复合驱等驱油体系在中后期油田开采中采油效率不高的问题,提出一种高效空气泡沫驱驱油技术。为验证高效泡沫驱的驱油效果,以延长油田1#地质条件为背景,探讨不同起泡剂浓度、矿化度下对空气泡沫驱的性能影响,从而筛选出空气泡沫驱的最优综合性能,通过驱替实验,对高效泡沫驱驱油机理进行观察。最后通过封堵能力评价验证了空气泡沫驱的性能与驱油机理。     

Experimental study of secondary and tertiary modes combined low salinity water and polymer flooding in sandstone porous media

Combined low salinity water (LSW) and polymer (LSP) flooding is the most attractive method of enhanced oil recovery (EOR). Considerable research has investigated effective mechanisms of LSP flooding. In this study, 10 laboratory core flood tests were carried out to evaluate the effects of LSW injection into samples without any clay particles, the timing of LSW injection, and the advantages of adding polymer to the injection water for EOR. Secondary and tertiary LSW injections were performed on sandpack samples with different wettability states and water salinity. Tertiary LSW injection after secondary synthetic seawater (SSW) injection in oil-wet samples resulted in 13% more oil recovery, while the water-wet sample showed no effect on the oil recovery. Secondary LSW injection in oil-wet porous media improved oil recovery by 8% of the original oil in place (OOIP) more than secondary SSW injection. Tertiary LSP flooding after secondary SSW injection in the oil-wet sample provided a recovery of 67.3% of OOIP, while secondary LSW injection followed by tertiary LSP flooding yielded the maximum ultimate oil recovery of about 77% of OOIP. The findings showed that the positive EOR effects of LSW and LSP flooding were the results of wettability alteration, pH increase, improved mobility ratio, better sweep efficiency, and oil redistribution. In addition, results showed that wettability alteration is possible without the presence of clay particles. The findings of this study can help for a better understanding of fluid propagation through the porous media and an investigation of delays in reaching ultimate oil recovery.     

Correlation between microscopic structural parameters and macroscopic flow behaviour of some polymer-surfactant systems suitable for tertiary oil recovery

Some materials, suitable for application in polymer-surfactant flooding used in tertiary oil recovery (EOR), have been characterized by static and dynamic light scattering and studied in respect to their suitability in various model brines by measuring their rheological and dynamic-rheological behaviour. Xanthan and polyacrylamides of different degree of hydrolysis have been used as polymers, an ethylene glycol sulfonate as surfactant. Correlations have been established between microscopic structural parameters (Hydrodynamic radius, radius of gyration, molar mass, shape of the polymers) and the macroscopic behaviour, such as viscosity and elasticity, being important rheological parameters for EOR application. Additional investigations on surface tension and long term viscosity study lead then to a judgement for the efficiency and long term stability of polymer-surfactant slugs in various reservoirs of different salinity.     

低渗透油藏泡沫驱油机理及应用现状研究

低渗透油气藏在世界范围内分布范围广,储量大,在新探明储量中占得比例越来越大,是全球油气资源增产的主要来源,合理高效的开发低渗透油藏中的油气资源,是未来面临的主要问题。泡沫驱油作为继水驱、气驱之后新的驱油方式,结合了气体和泡沫的优点,以独特的优势越来越得到人们的重视,是低渗透油藏提高采收率的又一个重要途径。分析了泡沫驱相对于其他驱油方式的优势,概述了泡沫驱油的驱油机理,简要分析了空气泡沫驱、氮气泡沫驱各自特点,对泡沫驱油在国内外油田的应用现状做了介绍。对泡沫驱油存在的问题做了阐述,并提出了泡沫驱油的发展方向。     

Experimental Study of In-Situ CO<Subscript>2</Subscript> Foam Technique and Application in Yangsanmu Oilfield

The Yangsanmu oilfield of Dagang is a typical heavy oil reservoir. After the maximum primary production (waterflooding), more than half of the original oil is still retained in the formation. Therefore, the implementation of an enhanced oil recovery (EOR) process to further raise the production scheme is inevitable. In this work, a novel in-situ CO₂ foam technique which can be used as a potential EOR technique in this oilfield was studied. A screening of gas producers, foam stabilizers and foaming agents was followed by the study of the properties of the in-situ CO₂ foam systems through static experiments. Core-flooding experiments and field application were also conducted to evaluate the feasibility of this technique. The results indicated that the in-situ CO₂ foam system can improve both the sweep and displacement efficiencies, due to the capacity of this system in reducing oil viscosity and interfacial tension, respectively. The EOR performance of the in-situ CO₂ foam system is better than the single-agent and even binary system (surfactant-polymer) flooding. The filed data demonstrated that the in-situ CO₂ technique can significantly promote oil production and control water cuts. These results are believed to be beneficial in making EOR strategies for similar reservoirs.     

Evaluating the performance of designed terpolymers for polymer flooding

In this work, polymeric materials designed for enhanced oil recovery (EOR) were evaluated for their intended application. Properties including viscosity, flow through porous media (resistance factor and residual resistance factor), and heavy oil displacement (incremental oil recovery) were assessed for designed terpolymers of 2-acrylamido-2-methylpropane sulphonic acid (AMPS), acrylamide (AAm), and acrylic acid (AAc). The same properties were evaluated for two commercially available reference materials (e.g., partially hydrolyzed polyacrylamides or HPAM) with similar characteristics, which allowed for direct comparison between the newly designed terpolymers and materials that are currently on the market for the polymer flooding application. The incremental oil recovery directly associated with polymer flooding, which includes both the polymer flooding and post-polymer waterflooding stages (excluding the initial waterflooding injection (or secondary) oil recovery), demonstrates that the designed terpolymers provided a higher incremental recovery (42% and 58%) than the reference materials (33% and 46%). Therefore, the terpolymers provided a higher contribution to incremental (or enhanced) oil recovery than the typical HPAM. Additionally, both designed terpolymers showed better injectivity in unconsolidated porous media and are less likely to cause plugging than the commercially available reference materials. Therefore, using a targeted design approach ultimately led to polymeric materials with excellent performance for EOR polymer flooding applications.     

聚驱后强弱碱三元体系极限驱油效果实验研究

随着大庆油田主力油层开发进入高含水阶段,急需聚合物驱后提高采收率接续技术方法。本文针对聚合物驱进入高含水阶段后进行三元驱的可行性展开了研究,利用达到超低界面张力条件的三元体系,模拟聚合物驱达到极限驱油效率后,开展三元体系极限驱油效果对比研究。结果表明:在聚合物驱达到极限采收率后,开展三元体系驱油能够进一步提高驱油效率,当弱碱三元体系中碱浓度较低时,聚驱后三元驱的采收率增加值较高,阶段极限采收率可达32.97%;当强碱三元体系中强碱浓度较高时极限采收率可达30.29%。在体系其他组成相同的条件下,基于强碱三元体系对注入系统和油层伤害较严重的问题,建议采用弱碱三元体系开展驱油生产。     

国内轻质油藏注空气、空气泡沫提高采收率效果分析

在重点调研国内油田空气、空气泡沫驱的基础上,论述了注空气、空气泡沫低温氧化技术的原理,对我国油田开展注空气、空气泡沫驱技术的实际效果以及潜力进行了的分析,认为注空气低温氧化工艺技术安全可控,不但可以解决我国储量丰富的低渗透油藏所面临的开发难题,而且可以进一步提高水驱、聚合物驱后油藏的采收率。随着技术进步,注空气低温氧化技术是我国乃至全世界注气提高采收率技术发展的必然趋势。并通过对现场应用情况分析,给出了对轻质油藏注空气、空气泡沫提高采收率的一些建议。