Nonlinear Behavior and Domain Feature at Oil/Water Interface

Studies on nonlinear behavior at oil/water interface membrane were performed. This system showed rhythmic oscillations and chaos of electrical potential in a given concentration domain. The nonlinear behavior response at the liquid membrane apparently resembled that of biological chemoreceptive membrane. The possibility of developing a new type of chemical sensor with the ability to simulate substance equilibrium in living organisms was suggested in the paper.

Prediction of curved oil–water interface in horizontal pipes using modified model with dynamic contact angle

In this study,interface shapes of horizontal oil–water two-phase flow are predicted by using Young-Laplace equation model and minimum energy model.Meanwhile,the interface shapes of horizontal oil–water twophase flow in a 20 mm inner diameter pipe are measured by a novel conductance parallel-wire array probe(CPAP).It is found that,for flow conditions with low water holdup,there is a large deviation between the model-predicted interface shape and the experimentally measured one.Since the variation of pipe wetting characteristics in the process of fluid flow can lead to the changes of the contact angle between the fluid and the pipe wall,the models mentioned above are modified by considering dynamic contact angle.The results indicate that the interface shapes predicted by the modified models present a good consistence with the ones measured by CPAP.

Formation of Uniform Oil-Soluble Fe_3O_4 Nanoparticles via Oil-Water Interface System

Nowadays,the novel oil water interface method has attracted a considerable attention owing to the advantages of mild reaction conditions,simple operation,low cost,and high efficiency.In this paper,uniform oil-soluble Fe_3O_4 nanoparticles(NPs) were synthesized by oil-water interface method from mixing iron tristearate of 0.067mol/L in cyclohexane with ferrous sulfate in water.The as-prepared products were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),vibrating sample magnetometer(VSM),Fourier transform infrared spectroscopy(FT-IR) and thermogravimetric analyzer(TGA).TEM images and XRD profiles showed that the size of the oil-soluble products ranged in 1.7-6.9 nm.VSM indicated that the Fe_3O_4 NPs were superparamagetic.FT-IR and TGA proved that oleic acid was combined to the surface of Fe_3O_4 NPs closely.TEM images and XRD profiles revealed that the most suitable reaction concentration of NH_3·H_2O,oleic acid/water in volume,reaction temperature and reaction time were 4.5 mol/L,50:1 000,80℃ and 6 h,respectively.The formation mechanism of the nearly monodispersed Fe_3O_4 NPs was that the preformed Fe_3O_4 nuclei were capped by oleic acid as early as the nucleation occurred in oil-water interface and subsequently entered into oil phase to stop growing.

Quantitatively probing interactions between membrane with adaptable wettability and oil phase in oil/water separation

The membrane method based on adaptive wettability shows great advantages in oil-water separation.At present,researches focus on the excellent application performance of the membrane material,while the quantitative analysis of interactions in oil-water separation is rarely recognized.Herein,we constructed an adaptable wettability membrane with multiple polymer networks by polydopamine(PDA)and mussel-inspired amphiphilic polymer.Based on the Owens three-probe liquid method,the surface energy of the modified membrane was verified to meet the adaptive wettability conditions,with surface energies(γ-8)of 147.6 mJ m^(−2)(superhydrophilic/underwater superoleophobic)and 49.87 mJ m^(−2)(superhydrophobic/superoleophobic),respectively.The adhesion or repulsion of the membrane to the oil phase under different conditions during the separation process was quantified by the chemical probe AFM technique.In addition,the oil-water selective separation mechanism was further analyzed in a simplified membrane microchannel model.The results show that the different wetting produces capillary additional pressure in opposite directions,resulting in different energies to be overcome when the oil or water passes through the microchannels,thus achieving selective separation.

Solvent switching and purification of colloidal nano- particles through water/oil Interfaces within a density gradient

Traditional post-treatment of colloidal nanoparticles （NPs） usually involves repeated centrifugation-wash-sonication processes to separate NPs from the original synthetic environment; however, such separation processes have either high energy cost or low efficiency and tend to cause aggregation. Here we show a general and scalable colloid post-processing technique based on density gradient centrifugation through water/oil interfaces. Such a one-step technique can switch the solvent in a colloid at almost any concentration without aggregation, and meanwhile purify colloidal nanoparticles by separating them from by-products and environmental impurities. Droplet sedimentation was shown to be the mechanism of this one-step concentration/purification process, and mathematical modeling was established to quantify the accumulation and sedimentation velocities of different NPs.

TRANSFER MECHANISM OF QUININE DRUG ACROSS THE OIL/WATER (O/W) INTERFACE

The transfer phenomena of quinine drug at the aqueous 1,2- dichloroethane (DCE)interface have been studied by the current- scanning polarography. The relationships be-tween the wave height and pH of aqueous phase, concentration of quinine as well as therate of water drop are discussed. The effect of supporting electrolyte, buffer solution andthe nature of organic solvent on the polarographic wave is studied. The transfer char-acteristics of quinine in aqueous phase and in organic phase are compared, The mono- pro-tonated and diprotonated quinines can both transfer at the interface so as to produce twopolarographic waves. The transfer process of quinine at the interface is simultaneouslycontrolled by diffusion and reestablishment of the disturbed protonated equilibrium ofquinine. A further investigation is made by chronopotentiometry. On the basis of thetheoretical analysis, the formulae of the limiting current are derived and discussed. Thetheoretical results are in agreement with the experimental ones. The transfer mechanismof quinine is put forward.

原油乳状液对20钢的腐蚀

以某油田原油和采出水为原料配制了不同含水率的油包水或水包油乳状液,利用失重法和电化学测试技术研究了20钢的腐蚀行为,分析了不同含水率和不同类型乳状液的腐蚀性。结果表明:乳状液的腐蚀性低于采出水的腐蚀性,且水包油乳状液腐蚀性大于油包水乳状液;由于油包水乳状液中原油在20钢表面吸附形成的油膜的完整性较好,20钢与水分子接触受到一定限制,腐蚀比较轻;随着含水率增大,油膜完整性逐渐受到破坏,乳状液腐蚀性明显变强;在水包油乳状液中,20钢与采出水直接接触,20钢表面只存在分散状的油膜,其对金属基体的保护作用较弱,随着含水率的增加,水包油乳状液对20钢的腐蚀接近于采出水;在油水界面处,20钢腐蚀严重,其腐蚀行为与在水包油乳状液中的类似。

曝气强化三维电极对含油废水水-油微界面破乳机制研究

三维电极体系下曝气对含油废水破乳除油效果有着显著性增强。本研究采用新型三相三维电级工艺,通过正交实验优化曝气条件,深入探讨强化水-油微界面破乳过程的控制机制。实验结果表明,曝气量由2.0 L/min降低到1.5 L/min,此时的COD和含油量分别为107、1.35 mg/L,满足回注水标准,且明显提高了节能效率。将曝气条件加入数值模拟,利用COMSOL软件模拟乳化油滴破乳及聚集的过程。在电场和气场力的共同作用下,增加了油滴拉伸变形的程度,破坏水-油微界面膜的机械强度,加速油滴脱稳过程,进而快速发生团聚。这一研究对强化电化学处理含油废水,具有重大的指导意义。

断溶体油藏追踪油水界面变化的新方法

在底水驱动型断溶体油藏中确定原始油水界面及追踪动态油水界面变化一直是制约剩余油预测的重要难题。此文聚焦油水界面的油藏本质,精细量化了储集体的孔隙体积,开发动态数据试井化处理计算水油体积比,动静结合等比例分配油水体积计算出原始油水界面。在油藏内部划分出油水界面,后期根据水驱动用过程评估曲线划分水驱阶段,追踪动态油水界面变化,避免陷入前期常规方法选取参数困难、计算误差大的困境。开发实践证实该方法得到的结果误差小,计算方便快捷,具有推广应用前景。

果胶复合提升米谷蛋白界面特性及Pickering乳液的贮藏稳定性

米谷蛋白(Rice Glutelin,RG)是一种常用食品乳化剂,但在中性pH值下,RG易聚集成疏水性大尺寸颗粒,导致其稳定性差、界面活性弱。该研究通过果胶静电复合修饰米谷蛋白,探究两者复合比例对颗粒的尺寸、接触角、界面吸附性能和界面膜结构的影响,在此基础上,以复合颗粒为界面稳定剂制备Pickering乳液,考察其粒径分布、微观结构、流变学性质及储藏稳定性。结果表明,当米谷蛋白与果胶质量比为1:1时,复合颗粒平均粒径为675.4 nm,接触角为64.23°,油-水界面张力从36.55 mN/m降低至13.00 mN/m,界面膜以弹性为主,弹性模量达46.07 mN/m,由此复合颗粒稳定的Pickering乳液具有最小的粒径(d4,3~31.1μm)、最高的表观黏度和储能模量。因此,果胶复合可以显著降低米谷蛋白的尺寸,并赋予其合适的表面亲疏水性,进而提升其降低界面张力和增加界面膜黏弹特性的能力,有利于制备高稳定Pickering乳液,为拓展米谷蛋白在食品乳液体系中的应用提供了新策略。

双子表面活性剂疏水链对油水界面行为的影响

双子表面活性剂(Gemini surfactants)已经被认为是传统的单子表面活性剂的新型替代品。然而,双子表面活性剂对油水界面影响的微观机制还没有被充分理解,通过构建了具有不同疏水链长度的双子表面活性剂并利用耗散粒子动力学(DPD)模拟研究了双子表面活性剂对油水界面行为的影响,研究结果表明,双子表面活性剂的表面活性随着疏水链长度的增加而增加,这也促使油水界面从层状转变为乳状液滴形态。温度的上升有利于降低油水界面张力使混合体系转变为乳液状态。表面活性剂疏水尾链和油珠之间的相互作用随着疏水尾链长度的增加而增加。

气顶边水油藏油气协同开发下流体界面运移特征

气顶边水油藏的开发,存在明显的油气水互侵现象,导致产量快速递减,开发难度增大。为了防止生产井过早停产,需明确流体界面运移特征,制定油气协同开发生产制度。通过油藏数值模拟方法,建立了月东油田气顶边水油藏实际模型与机理模型,根据气顶与边水作用能量强弱,将油气协同开发区域划分为边水控制区、气顶控制区和气顶边水联合控制区三类进行研究,综合评估气窜、水淹、油侵风险,明确油气、油水界面运移特征并形成运移速度图版。结果表明:随着开发的进行,气顶膨胀导致油气界面从油藏顶部向油井方向运移,边水侵入导致油水界面从油藏底部向油井与气井方向运移,油井存在气窜与水淹的风险,气井存在水淹与油侵的风险,剩余油主要分布在气顶下部和井间高部位,确定月东油田气顶边水油藏合理采气速度为6%~8%。基于实际与理论研究形成的成果认识为气顶边水油藏油气协同高效开发提供理论指导。

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.

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。

水油双相化妆水的制备及性能研究

通过考察水油界面高度、水油双相是否澄清透明、感官评价、稳定性等维度,对水油双相化妆水的开发进行了摸索和优化。结果表明,添加角鲨烷︰聚二甲基硅氧烷=1︰1、0.05%聚山梨醇酯-20、1%柠檬酸和柠檬酸钠组合物、0.02%透明质酸钠等成分制得的水油双相化妆水的水油界面清晰,稳定性良好,肤感清爽不粘腻,同时给肌肤带来较好的柔软感。

储层颗粒定量荧光实验关键影响因素分析及方法优化——以渤海海域为例

针对储层定量荧光实验参数在古油藏丰度评价中频频失真的问题,根据该实验灵敏、易受荧光干扰的特性,设计了二氯甲烷萃取破碎颗粒测试实验,结合全岩分析、微量元素分析,明确辉绿岩、混合花岗岩、碳酸盐岩样品干扰物与纯包裹体QGF index比值分别为0.85~1.16、3.20~19.94、0.97~5.84。基于此,建立了储层颗粒定量荧光实验优化方法,去除了干扰物荧光附加值;同时修正QGF intensity计算范围,避免轻质、重质油气包裹体QGF index计算失真。将优化方法应用到渤海海域QHD5-B井,识别古油水界面位于3880 m,古油水层QGF index值判别标准为3.1。

关于海上油田油水界面测量情况的探讨

随着海上油田产液量的日益增高,原油处理流程脱水效果的好坏将直接影响到外输原油的品质以及下游回注生产水的水质。为了保证原油在处理流程中达到良好的脱水效果,需要对处理流程中三相分离器及电脱水器的油水界面进行准确测量。通过对三相分离器运行效果及油水界面测量情况分析,电脱水器运行效果及油水界面测量情况分析,提出了一种油水界面测量的改进方法。经油田现场实际应用一年的结果验证,油水界面测量方法调整后能够准确测量出油水界面,油水处理效果改善明显,电脱水器运行电流明显降低,水相出口含油率由250 mg/L下降至120 mg/L;改进后系统稳定性得到提高,上游来液波动影响明显降低,提高了生产效率,降低了生产成本。

储层岩石热物性变化规律研究现状与展望

储层岩石在各种因素影响下的热物性变化规律对油藏的开发效果有一定程度的影响,这种影响在稠油油藏的开发中更为显著。近年来,随着油藏精细化开发的目标被提出,储层岩石热物性变化规律研究的重要性也愈发凸显。对储层岩石热物性变化规律的研究现状进行了介绍,并对今后储层岩石热物性变化的研究趋势进行了展望。

基于分子动力学模拟的α-SiO_(2)纳米颗粒油-水界面吸附行为研究

纳米颗粒相界面吸附与自组装被广泛应用于石油采收、泡沫浮选、药物输送及新型功能材料等研究领域。然而,由于溶剂化力、静电斥力等多种相互作用所导致的吸附势垒,纳米颗粒自发吸附至界面的过程受到阻碍。基于分子动力学方法研究了α-SiO_(2)纳米颗粒相界面吸附动力学特征,深入分析了水化层结构及离子浓度对颗粒吸附行为的影响。首先,通过修饰表面基团获取了不同亲疏水性α-SiO_(2)纳米颗粒的吸附特征:纳米颗粒自发扩散至亚界面后会经历弛豫吸附至界面、快速吸附以及在界面区域经历一段弛豫后达到动态平衡三个过程。随后,从径向分布函数、角度分布、氢键密度分布等对纳米颗粒水化层结构以及氢键结构和进行了量化和比较,通过水化层内水分子驻留自相关函数以及氢键寿命分析了水化层结构及氢键结构的动力学特性。结果表明:水化层结构依赖于所作用颗粒的表面特性,与亲水表面相比,水分子在疏水表面具有明显的择优取向和更强的流动性;表面-水间氢键相互作用和水化层内特殊氢键结构是影响颗粒吸附的重要原因;不同离子效应可以通过共同作用干扰氢键结构以促进纳米颗粒相界面吸附。本研究为理解纳米颗粒相界面吸附动力学特性以及吸附壁垒形成机制提供参考,对于纳米颗粒相界面可控吸附在石油采收、新型功能材料等应用领域具有指导意义。

分离罐油水多界面监测系统设计

原油开采过程中分离罐液位检测手段主要靠人工完成,存在低效率及安全隐患等问题。本文利用基于射频导纳原理的多点测控技术,研制出新型分离罐罐油水多界面及含水率测量装置,实现对油田分离罐内的油水界面进行在线监测。