Experimental investigation the effect of nanoparticles on micellization behavior of a surfactant: Application to EOR

Chemical stimulation such as surfactant flooding in petroleum reservoirs makes efforts to produce remained oil and improve sweep efficiency by means of different phenomena such as lowering interfacial tension and wettability alteration of reservoir rock. Implementing concentration of surfactant through surfactant flooding is one of the big challenges while interfacial tension between surfactant solution and oil after certain concentration involves little changes such as critical micelle concentration (CMC). This article highlights the effect of nanosilica on CMC of Zyziphus Spina Christi, as sugar-based surfactant, in aqueous solutions for enhanced oil recovery and reservoir stimulation purposes. A conductivity approach was selected to assess the CMC of the introduced surfactant in aqueous solution at 25°C. The influence of nanosilica concentrations on CMC variation of introduced surfactant is considered. It is found that CMC of introduced surfactant decreased while the concentration of the nanosilica increased. Results from this study can aim in optimum condition selection of surfactant flooding as an enhanced oil recovery ends.     

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.     

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.     

降低启动压力的表面活性剂体系在朝阳沟油田的应用

针对朝阳沟低渗透油田注水过程中注水压力上升较快、欠注严重的问题,进行了朝阳沟油田降压增注表面活性剂体系的筛选工作,最终确定表面活性剂体系的配方为0.2%石油磺酸盐类表面活性剂T702-40^#+0.5%Na₂CO₃。实验结果表明,该表面活性剂体系与原油间平衡界面张力能够达到2×10^-2mN/m,耐温、抗盐性好,与朝阳沟油田注入水和地层水配伍性好,能够使岩石的润湿性发生反转,比水驱提高采收率5%左右。该表面活性剂体系驱替计算得出的可流动渗透率值约比水驱可流动渗透率值大15%,具有明显的降低启动压力的作用,并进行了表面活性剂体系降低启动压力的机理分析。朝阳沟油田朝82-152井区矿场试验结果表明,该表面活性剂体系能够降低启动压力,使油层吸水能力提高,使低渗透储层动用比例提高,7口油井累积增油1768t。     

低渗透油藏的热水驱研究

热水驱仅包括两个被加热相的流体,热水驱的主要机理是热膨胀,降低黏度,润湿相改变和油水界面张力的降低。热水驱实验使用的岩心样本取自某稠油低渗透油藏,主要是未被饱和的砂岩。实验在相同的油藏压力,不同的温度（范围在110oC以内）和不同种类的原油下进行的。对比了每个试验的最终原油采收率、残余油饱和度、束缚水饱和度、和压力降落。应用JBN方法分析了动态恒温驱替的结果,从而得到岩心的相对渗透率及低渗透砂岩中温度对油水相对渗透率的影响。结果显示在低渗透率的砂岩中使用高温热水在较高压力下驱替稠油,也有可能获得较高的采收率。在稠油体系中,原油生产的热水注入率比在中质油和超稠油要高,但是在传统稠油油藏它的价值很少被报道。另外,研究发现当岩石被加热时,油水的相对渗透率取决于温度,而残余油饱和度会降低,束缚水饱和度会增加。     

非均相复合驱油体系设计与性能评价

为进一步提高聚驱后油藏采收率,针对聚驱后油藏非均质性强、剩余油普遍分布的特点,提出了非均相复合驱油体系。非均相复合驱油体系包括黏弹性颗粒驱油剂（PPG）、表面活性剂和聚合物。通过研究黏弹性颗粒驱油剂的溶胀能力、黏弹性、滤过能力和在岩心中运移性能,及其与表面活性剂、聚合物之间相互作用,得到了适合于胜利高温高盐油藏和聚合物驱后油藏的非均相复合驱油体系1000 mg/L PPG＋1000 mg/L聚合物＋0.3％胜利石油磺酸盐＋0.1％非离子表面活性剂1709。结果表明,PPG可遇水溶胀,耐盐性能好,在油藏中具有封堵和运移性能,较单一聚合物能够更好地提高波及体积。在含水98％条件下注入0.3倍孔隙体积的非均相复合驱油体系,聚合物驱后提高采收率13.6%(OOIP)。该体系可应用于高温高盐油藏或聚合物驱后油藏大幅度提高采收率。     

以大庆减压渣油为原料的高效、廉价驱油表面活性剂OCS的制备与性能研究

针对现有三元复合驱油体系化学剂费用投入大，经济效益差的缺点，以廉价的大庆减压渣油为原料在实验室内合成出廉价的驱油用表面活性剂OCS，并初步评价了所得OCS样品的性能。结果表明，OCS表面活性剂制备重复性好，性能稳定。OCS表面活性剂具有优异的降低原油一地层水界面张力的能力，在NaOH存在条件下，能在较宽的碱浓度范围内使大庆四厂原油的油-水界面张力降至10^-3mN／m。在Na2CO3存在条件下，能在较宽的碱浓度范围内使大庆四厂原油、华北油田古一联原油及胜利孤东采油厂原油的油-水界面张力降至10^-3mN／m。在无碱条件下，对于大港油田枣园1256断块原油，当OCS表面活性剂含量达到0．1％时，油-水界面张力即可降至10-3^mN／m。对大庆四厂原油的驱油试验结果表明，OCS表面活性剂、碱和聚合物三元复合体系(ASP)的驱油效率比水驱提高20％以上。     

ROS驱油表面活性剂在高温高盐油藏中的应用

研究了 ROS 驱油表面活性剂用于华北油田晋45断块的有关性能,包括溶解性、界面张力性能、耐高温性能、吸附性能以及岩心驱替实验。结果表明,ROS 驱油表面活性剂在晋45断块地层水中具有良好的溶解性和耐高温性能;当 ROS 质量分数大于0.2%时,油水界面张力可以达到10~(-3)mN/m 的超低值;在设计注入质量分数0.3%附近,吸附量小于1.0 mg/g,能够满足华北油田晋45断块对表面活性剂驱油的要求;质量分数为0.2%的 ROS 驱油表面活性剂驱可比水驱提高采收率13.3%。     

深层缝洞型油藏烃气混相驱可行性及影响因素

针对塔河油田深层缝洞型油藏,基于室内相态实验,采用经验公式法、拟三元相图法和细管模拟法计算烃气与原油最小混相压力,并通过数值模拟,研究了油藏前期注入氮气和原油品质对烃气混相驱的影响。研究结果表明：3种方法计算得到的原油最小混相压力远小于地层实际平均压力,研究区深层缝洞型油藏烃气混相驱具有较好的可行性;油藏前期注入氮气对烃气混相驱影响显著,注入氮气波及的储集层区域,烃气与原油的最小混相压力变高,氮气含量与注入烃气含量比大于1.208时,无法形成混相;原油品质对烃气混相驱影响显著,原油中的轻组分含量越高,烃气与原油最小混相压力越低,原油中的重组分含量越高,烃气混相驱最终采收率越低。     

大庆油田强碱三元复合驱表面活性剂配方优化

烷基苯磺酸盐表面活性剂的性能直接影响强碱三元复合驱的开发效果。通过研究原油组成、油砂吸附等对烷基苯磺酸盐表面活性剂浓度及强碱三元复合体系界面张力的影响,建立了原油分子量与表面活性剂当量之间的定量匹配关系。结果表明,依据该定量匹配关系选择合适当量的表面活性剂可使三元复合体系与大庆地区 不同原油间达到超低界面张力,提高了强碱三元复合体系的适应性;原油组成影响表面活性剂在油水相中的分配比例,原油中的沥青质含量越高,水相中的表面活性剂浓度越低,原油组成对表面活性剂当量的影响较小;油砂吸附改变了表面活性剂的当量及组成分布,导致三元体系中表面活性剂的浓度降低、三元体系界面张力升高,可采取增加高碳组分、调整表面活性剂当量的方法,扩大复合体系在地下运移过程中的超低界面张力作用距离。图11表3 参16     

表面活性剂驱在薛岔低渗油区的效果分析

为进一步提高水驱采收率,薛岔油区实施了表面活性剂驱矿场试验。试验结果表明,表面活性剂驱有效抑制了单井产量递减,单井日产油量提高。在水下分流河道主体砂体上,砂层厚度、孔隙度、渗透率值相对较大,表面活性剂可以更好地驱替残余油,见效更明显。表面活性剂可以使得油水等渗点右移,岩石表面亲水性进一步增强,使油水两相相对渗透率均得到提高,薛岔试验区注入压力下降0．7MPa,也证实了驱油剂将近井地带残余油被驱替,水相渗透率得到提高。     

OCS表面活性剂工业品的界面活性及驱油效率

针对现有三元复合驱油体系化学剂费用投入大,经济效益差的缺点,利用廉价的大庆减压渣油为原料合成了驱油用表面活性剂OCS.测试结果表明,OCS表面活性剂工业品具有优异的降低原油-地层水界面张力的能力,能在较宽的碱浓度和表面活性剂浓度范围内使不同大庆采油厂原油的油-水界面张力降至10^-3mN/m.在无碱条件下,对于大港油田枣园1256断块原油,当OCS活性剂质量分数达到0.2%时,油-水界面张力即可降至10^-3mN/m.大庆原油的平面模型驱油试验表明,OCS表面活性剂、碱和聚合物三元复合体系（ASP）的驱油效率比水驱提高20%以上.     

表面活性剂─聚合物驱复合段塞的优化设计

文中对蒙古林砂岩油藏原油粘度相对较高,水驱效率低的特点,提出了一种新型复合驱油体系。室内在对油水界两张力、配伍性、吸附量等方面性能评价的基础上,进行段塞优化设计。实验结果表明：该复合段塞采用混合注入的方式,不仅能够有效地降低油水界面张力,减少表面活性剂在岩石表面的吸附,而且具有很好的保持流度的能力．根据蒙古林油藏条件进行模拟实验和油藏数值模拟,复合段塞被设计为：表面活性剂浓度为0.5％,生物聚合物浓度为1400mg／L,段塞大小为0．1PV,注入方式采用混合注入,可提高原油采收率19％。     

利用表面活性剂降压增注提高采收率技术

在绝对渗透率难以改变的客观条件下,通过改变油、水及岩石间的界面张力,从而改善油、水渗流性,提高水相渗透率,降低低渗透油层注入压力,并在一些低渗透油田开展了低浓度活性剂降压增注试验研究,取得了一定的效果。室内实验结果表明,在岩心中注入表活剂体系,可以不同程度地降低注入压力,最好情况可以达到40%~60%。     

龙虎泡油田活性水驱油室内实验研究

针对大庆外围低渗透油田注水压力高、吸水能力差以及水驱采收率低等问题,选取龙虎泡油田进行活性水驱油室内物理模拟实验研究。表面活性剂筛选实验结果表明,十二烷基苯磺酸钠配制的活性水溶液/原油体系界面张力可达0.2041 mN/m,且与地层水配伍性良好,比水驱采收率提高16.6%。驱油实验结果表明,水驱速度、活性水浓度、活性水注入量、注入时机均对驱油效果产生一定的影响,当水驱速度为1.0 mL/min、活性水浓度为0.3%、活性水注入量为0.3 PV 时驱油效果最佳。现场实验应选取低含水井进行活性水驱油,当含水率较高时,适当提高活性水浓度以保持开发效果。     

非均质油藏复合驱合理界面张力实验研究

针对油田三元复合驱油实际需求,通过调整活性剂、聚合物和碱的类型和配方组成,在两种具有大庆油田油藏典型地质特征的物理模型上对低活性剂浓度三元复合体系的适应性进行了实验评价。结果表明,非均质油藏三元复合驱应当兼顾扩大波及体积和提高洗油效率。将复合体系中表面活性剂和碱的浓度分别降低到0.1%和0.8%,驱替相与被驱替相间界面张力保持为0.01mN/m,并适当增大聚合物相对分子质量或增加聚合物浓度,低活性剂浓度三元复合体系驱原油的采收率可以增加20%以上。     

Implementing radial basis function neural network for prediction of surfactant retention in petroleum production and processing industries

Chemical flooding is an effective way to gain higher oil recovery as part of a tertiary oil recovery scheme. There are several variables contribute in surfactant retention in petroleum production including type of rock, pH, chemical structure of surfactant, salinity of formation water, acidity of oil, mobility, microemulsion viscosity, and cosolvent concentration. Although different theoretical studies on the mechanisms of surfactant retention are reported in the literature there is little research on the development of an accurate and effective model for prediction of surfactant retention in petroleum production. In this study, radial basis function was developed based on experimental dynamic surfactant retention data. The experimental data include a wide range of conditions. Results of the modeling study showed that the developed model is very accurate and robust in prediction of actual surfactant retention data. In addition, the comparison between the proposed model in this study and available models in literature showed the superiority of this model.     

Performance improvement of ionic surfactant flooding in carbonate rock samples by use of nanoparticles

Various surfactants have been used in upstream petroleum processes like chemical flooding. Ultimately, the performance of these surfactants depends on their ability to reduce the interfacial tension between oil and water. The surfactant concentration in the aqueous solution decreases owing to the loss of the surfactant on the rock surface in the injection process. The main objective of this paper is to inhibit the surfactant loss by means of adding nanoparticles. Sodium dodecyl sulfate and silica nanoparticles were used as ionic surfactant and nanoparticles in our experiments, respectively. AEROSIL~? 816 and AEROSIL~?200 are hydrophobic and hydrophilic nanoparticles. To determine the adsorption loss of the surfactant onto rock samples, a conductivity approach was used. Real carbonate rock samples were used as the solid phase in adsorption experiments. It should be noted that the rock samples were water wet. This paper describes how equilibrium adsorption was investigated by examining adsorption behavior in a system of carbonate sample(solid phase) and surfactant solution(aqueous phase). The initial surfactant and nanoparticle concentrations were 500–5000 and 500–2000 ppm, respectively. The rate of surfactant losses was extremely dependent on the concentration of the surfactant in the system, and the adsorption of the surfactant decreased with an increase in the nanoparticle concentration. Also, the hydrophilic nanoparticles are more effective than the hydrophobic nanoparticles.     

洞-缝-洞介质中水驱油注采规律研究

为了揭示缝洞型油藏的注采机理,研究了缝洞介质中的水驱油规律。利用有机玻璃制作了一组不同裂缝宽度的洞-缝-洞组合模式物理模型,开展了物理模拟试验,分析了水驱后剩余油分布规律及形成机制,并研究了注入速度、裂缝宽度、毛管力对水驱油采收率、含水率的影响,通过相似理论计算得到了不同溶洞高度对应的临界裂缝宽度。研究发现:水驱后的剩余油主要存在于未波及的单向连通溶洞与裂缝中,表面活性剂溶液驱后的剩余油主要存在于单向连通溶洞的上部;当溶洞内的油水界面到达一定高度产生的压差克服毛管力作用时,水才能进入裂缝底部;注入速度越小、裂缝宽度越大、毛管力越小,模型采收率越高;溶洞高度越高,其对应的临界裂缝宽度越小。研究结果表明,表面活性剂驱可以提高洞-缝-洞型油藏的采收率。      

东营凹陷岩性油气藏成藏动力学特征

东营凹陷岩性油气藏主要为砂岩透镜体油气藏和砂岩上翘尖灭油气藏。受地层压力的影响,东营凹陷岩性油气藏表现为不同的成藏动力学特征。在正常压力系统,岩性油气藏油气运移的驱动力主要为浮力,油气沿断裂、不整合面或储集岩向上运移并在岩性圈闭中聚集成藏,运移相态主要为游离相;而在异常高压系统,油气运移的驱动力主要为压实和欠压实作用下产生的地层压力差,这种压力差可以驱动油气由高势区向低势区运移并在岩性圈闭中成藏,运移相态主要为混(溶)相和游离相。