Effects of Different Heavy Crude Oil Fractions on the Stability of Oil-in-water Emulsions —— Isolation of functional fractions from heavy crude oil and study of their properties

The functional fractions (acid, basic, amphoteric and neutral fractions) are isolated from the Liaohe Du-84 heavy crude oil and Shengli Gudao Kenxi heavy crude oil by ion-exchange chromatography, but the conventional fractions (saturates, aromatics, resins and asphaltenes) are also isolated from the heavy crude oil. These components have been characterized by spectroscopic methods (FT-IR), namely acid number, basic nitrogen number, ultimate analysis and molecular weight measurements using vapor pressure osmometry (VPO). The ion-exchange chromatography method based on separation by a functional group induces a little change on the nature of the crudes and reasonable mass balances can be easily obtained.

Experimental investigation of the effects of various parameters on viscosity reduction of heavy crude by oil-water emulsion

The effects of water content, shear rate, temperature, and solid particle concentration on viscosity reduction （VR） caused by forming stable emulsions were investigated using Omani heavy crude oil. The viscosity of the crude oil was initially measured with respect to shear rates at different temperatures from 20 to 70℃. The crude oil exhibited a shear thinning behavior at all the temperatures. The strongest shear thinning was observed at 20℃. A non-ionic water soluble surfactant （Triton X-100） was used to form and stabilize crude oil emulsions. The emulsification process has significantly reduced the crude oil viscosity. The degree of VR was found to increase with an increase in water content and reach its maximum value at 50 % water content. The phase inversion from oil- oil emulsion occurred at 30 in-water emulsion to water-in- % water content. The results indicated that the VR was inversely proportional to temperature and concentration of silica nanoparticles. For water-in-oil emulsions, VR increased with shear rate and eventually reached a plateau at a shear rate of around 350 s^-1. This was attributed to the thinning behavior of the continuous phase. The VR of oil-in-water emulsions remained almost constant as the shear rate increased due to the Newtonian behavior of water, the continuous phase.

Effects of Different Heavy Crude Oil Fractions on the Stability of Oil-in-water Emulsions—the film properties of heavy crude functional components and water system

A series of π-A isotherms are drawn to study the film properties of the components with Langmuir-Blodgett technique. The effects of the aromaticity of spread solvents and pH value on the air/water film formed by the components are investigated. Acid fraction and asphaltene can form stable two-dimensional insoluble films on an air/water surface. The surface film pressure of acid fraction and asphaltene is higher and more stable than that of the other fractions. The surface film pressure of the fraction increases evidently under the basic condition (pH=12). The results show that the interfacial activity of acid fraction and asphaltene is superior to that of the other fractions and the basic condition is favorable to the stability of the O/W emulsion.

Experimental measurements of water content in crude oil emulsions by terahertz time-domain spectroscopy

We measured the water content （0.01% 0.25% w/w） in crude oil emulsions using terahertz time-domain spectroscopy （THz-TDS）. To improve the precision and range of the measurements, we used 1 and 10 mm thick quartz cells. The experiments were performed at 20 ℃ and the THz wave was transmitted vertically to the samples and detected on the other side. The experimental results suggest linear relation for the THz absorption coefficient and the water content of the crude oil emulsions in the observed range. The linear dependence facilitates high-precision measurements of the water content of crude oil. This suggests the potential of THz-TDS in determining the water concentration in crude oil and borehole fluid identification.

Study on Viscoelastic Behaviors of Waxy Crude Water-in-Oil Emulsion

Emulsion of waxy crude oil is one of the common states in the subsea pipeline. At low temperatures in offshore environment, waxy crude oils with water could form the crude oil emulsion gel of oil-in-water emulsion. Thus, the waxy crude oil emulsion viscoelastic behavior for deep sea transportation and restarting pipeline safety is particularly important. By means of MASIII HAAKE rheometer which is produced by German company, waxy crude oil emulsion viscoelastic behavior is explored at different volumetric water contents and different shear stresses. By analyzing the rate of change of shear rate in the initial stage, the influence rules of viscoelastic properties were summarized, with the change of volumetric water content and the applied shear stress and based on the experimental results, the law of emulsion is explained from the micro level. It is proposed that brittle fracture exists between wax crystals, and flexible fracture was found in the interaction between water droplets and wax crystals.

Emulsification of Indian heavy crude oil using a novel surfactant for pipeline transportation

The most economical way to overcome flow assurance problems associated with transportation of heavy crude oil through offshore pipelines is by emulsifying it with water in the presence of a suitable surfactant.In this research,a novel surfactant,tri-triethanolamine monosunflower ester,was synthesized in the laboratory by extracting fatty acids present in sunflower（Helianthus annuus）oil.Synthesized surfactant was used to prepare oil-in-water emulsions of a heavy crude oil from the western oil field of India.After emulsification,a dramatic decrease in pour point as well as viscosity was observed.All the prepared emulsions were found to be flowing even at 1°C.The emulsion developed with 60%oil content and 2wt%surfactant showed a decrease in viscosity of 96%.The stability of the emulsion was investigated at different temperatures,and it was found to be highly stable.The effectiveness of surfactant in emulsifying the heavy oil in water was investigated by measuring the equilibrium interfacial tension（IFT）between the crude oil（diluted）and the aqueous phase along with zeta potential of emulsions.2wt%surfactant decreased IFT by almost nine times that of no surfactant.These results suggested that the synthesized surfactant may be used to prepare a stable oil-in-water emulsion for its transportation through offshore pipelines efficiently.

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.

Red/NIR/SWIR multi-band persistent luminescent nanoparticles as ultrasensitive multi-channel tracers in water and crude oil/water emulsions

We report the use of CaTiO_(3):Pr^(3+)multiband persistent luminescent nanoparticles,which can simultaneously emit red(610 nm),near-infrared(893 nm),and short-wave infrared(1040 nm)photoluminescence and persistent luminescence,as the tracer nanoagents for water tracer sensing.By using a spectrofluorometer,an Si charge-coupled device(CCD)camera and an InGaAs array camera as the detection tools,we evaluated the sensing capabilities of the three emission bands of CaTiO_(3):Pr^(3+)nanoparticles in brine water solutions and crude oil/brine water emulsions in both photoluminescence mode and persistent luminescence mode.Among these different detection combinations,the persistent luminescence-based Si CCD camera imaging exhibits the best sensing performance with the detection limits being at a single-digit ppb level for the 610 and 893 nm bands and about 100–200 ppb for the 1040 nm band in both water solutions and crude oil/water emulsions,while the photoluminescencebased Si CCD camera imaging has a much higher detection limit of~10 ppm in water solutions and of~200 ppm in oil/water emulsions.The persistent luminescence-based InGaAs array camera imaging to the 1040 nm band has the worst performance with the detection limits higher than 200 ppm for both solutions.The sensing performances of the spectrofluorometer to photoluminescence signals and persistent luminescence signals in the two solutions are about the same,with the detection limits being around 100–200 ppm.

Efficient demulsification of ultralow-concentration crude oil-in-water emulsion by three-dimensional superhydrophilic channels

Efficient extraction of crude oil,the major energy resource of current concern and high demand worldwide,is of paramount importance in both energy and environmental fields.However,it remains a great challenge to separate the crude oil-in-water emulsions with an ultralow oil content of<200 ppm.Here,the three-dimensional and superwetting channels are developed by coating titanium foams with anodic TiO_(2) nanotube arrays.The channels render superhydrophilic and underwater superoleophobic feature,which enables rapid formation of water channels that expel the oil droplets.A high separation efficiency of ∼96.8% and low total organic carbon content of ∼6 ppm are thus achieved for the ultralow-concentration crude oil-in-water emulsions.The pressure and time dependence of the separation process is systematically studied with a critical pressure of 12.25 kPa.Such a high performance is close to the theoretical limit imposed by the ultralow concentration,and shows obvious advances over either organic membranes or inorganic frameworks.

A review on the rheology of heavy crude oil for pipeline transportation

Given the combination of rising global energy demand and the decline in conventional crudes, heavycrudes are generally considered to be the future energy resource. In many regions of the world, heavycrude oil must be transported through pipelines from the point of production to storage facilities orrefineries. The transportation of heavy crude oil by pipeline poses serious problems related to the highviscosity and flow difficulties, particularly in cold climates or offshore conditions. Indeed, the viscosity ofcrude oil is an important physical property that influences and controls crude oil flow in pipelines.Viscosity introduces resistance to movement by causing a shear or frictional force between the fluidparticles and the boundary walls. This high viscosity means that the pumping power requirements forcrude oil in a long-distance pipeline are very high in order to overcome the increasing shear and frictionforces. Therefore, in order to facilitate the pumping of these viscous oils and reduce operating expensesand the negative impact of pressure drops in pipelines during flow and processing, their viscosity mustbe reduced. Various techniques are used to increase pumping efficiency and improve the flow of crude oilthrough the pipeline, which may present logistical, technical or economic disadvantages for a givenapplication. The main ones are the addition of surfactants or polymers, dilution with lighter crudes, useof water as annular fluid, thermal remediation and emulsification with surfactant (O/W). This reviewhighlights the methods currently used to enhance the fluidity of heavy crude oil in pipelines behindrheology improvement, in particular the addition of additives and the use of water and surfactants tocreate a stable emulsion of heavy crude oil in water have been considered.

基于水包稠油型乳状液黏度与稳定性的乳化剂配方研究

采用单因素实验法考察了一种稠油乳化剂配方中包括油酸钠(NaOA)、椰油酰胺丙基甜菜碱(CAB-35)、无机碱(Na_(2)CO_(3))、有机碱(三乙醇胺(TEOA))4种组分的配比和剂量。考察了乳化温度、含油率及Na^(+)和Ca^(2+)含量等指标对稠油乳状液流变性质和稳定性的影响,并采用响应曲面法优化上述指标后确定了乳化剂的配方。实验结果表明,表面活性剂与稠油的相互作用对乳状液的表观黏度具有显著影响;而表面活性剂与碱的相互作用则显著影响稳定性。优化的配方为:表面活性剂含量1.5%(w)(m(NaOA)∶m(CAB-35)=2∶1),碱含量0.4%(w)(m(Na_(2)CO_(3))∶m(TEOA)=1),乳化温度40℃,含油率为71%(w);乳状液的表观黏度为38.26 mPa·s,稳定性为90.28%。经济配方为:表面活性剂含量1.0%(w)(配比不变),碱含量0.2%(w)(配比不变),乳化温度40℃,含油率为75%(w);乳状液表观黏度为45.92 mPa·s,稳定性为87.01%。

Gemini稠油乳化降黏剂GMS-1的合成及应用性能

稠油乳化降黏剂GMS-1是M=814的磺酸盐型孪二连表面活性剂，根据东辛营27馆陶组稠油（50℃黏度8769mPa·s）所含脂肪酸中C16和C18组分所占比例较大的特点，由C16、C18脂肪醇、环氧丙磺酸、乙二胺合成并用红外光谱法确认了化学结构。其表面活性远大于常用各种类型的普通表面活性剂。用矿化度30g／L的含钙镁盐水配制的0．1％～1．5％的GMS-1水溶液与该稠油在50℃、油水比≤70／30时形成低黏度O／W乳状液（附典型电镜照片），油水比85／15时仅在GMS-1质量分数较高时形成较低黏度乳状液；当油水比70／30、温度在30～60℃范围时，1．0％～2，0％GMS-1水溶液与稠油形成的乳状液的黏度低且基本上不随温度而变，而0．1％～1．0％GMS-1水溶液与稠油形成的乳状液的黏度则随GMS-1质量分数的减小和温度的降低而升高；在5.0～90g／L范围内，矿化度（NaCI质量浓度）对乳状液黏度的影响与温度相似。GMS-1耐温性好，形成的稠油乳状液稳定性好。在营27x5机抽井使用GMS-1，使产出的含水17．2％的原油井口黏度由15987mPa·S降至484.9mPa·S。图5表5参4。

渤海C油田预钻井原油乳化对储层伤害实验研究

渤海C油田导管架期间首批12口预钻井在生产过程出现了生产压差高产量低的现象,分析认为原油乳化堵塞是潜在伤害因素。为了明确原油乳化堵塞机理,为产能恢复措施制定提供指导,针对该批低产井开展原油乳化堵塞实验研究。实验结果表明:当含水率为20%时,原油乳状液黏度为最高值10.9 mPa·s,为原油乳化反相点,乳状液类型为油包水(W/O)型;当含水率大于20%时,乳状液黏度降低,类型为水包油(O/W)型;原油高含水时,乳状液类型为O/W型,降低储层渗透率25.21%,对储层伤害相对较小;原油低含水时,乳状液类型为W/O型,降低储层渗透率75.01%,对储层伤害大。随着乳状液质量浓度从1000 mg·L^(-1)增加至4000 mg·L^(-1),岩心渗透率伤害程度最高达到50%。以I01H和I28H井为例,结合实验结果对实际生产动态进行分析,两口井生产初期含水率升高至20%后,生产压差不变,采液指数下降,说明原油发生乳化并堵塞近井地层,与实验结果一致。

超临界多元热流体发生及地下原位转化开采重质油理论与技术

稠油和低成熟页岩等重质油资源潜力巨大,但其低流动性和高干酪根含量导致难以高效开采,针对现有注蒸汽等方法存在采收率低、加热效率差和热流体成本高等问题,提出了以超临界水热化学转化为核心的重质油原位转化开采新思路,基于超临界水独有的高溶解性、高扩散性和高反应性,采用油田有机废液为原料通过超临界水气化与氢氧化原理生产超临界多元热流体,并将超临界多元热流体注入地层加热储层、同时原位转化稠油和干酪根生成轻质油气,通过超临界混相驱大幅提高采收率,从而实现了高效、清洁、低成本的热流体生成、储层加热转化与油气高效采出。研究结果表明,油田有机废液碳转化率超98%,稠油岩心驱替效率超97%,单井4轮次吞吐效率超75%,低成熟页岩有机质生烃制油气有机碳转化率达60%。该技术的突破可对变革传统重质油开发方式、保障我国油气能源安全提供参考。

基于原油物性定量表征的油包水乳状液黏度预测模型

准确预测原油乳状液的黏度对于油水混输管道的设计和运行具有重要意义。将8种不同物性的原油制备成油包水乳状液,通过流变仪对乳状液的黏度特性进行测定,研究了温度、含水率及剪切速率对油包水乳状液表观黏度的影响。以实验数据为基础,并对原油物性进行定量表征,建立了适用于不同原油、不同剪切条件的油包水乳状液黏度预测模型。结果表明,油包水乳状液的表观黏度随温度的升高而减小,随含水率的增加而增大,随剪切速率的增加而减小;具有剪切稀释性,可采用幂率模型来描述油包水乳状液的流变特性。随着含水率上升,油包水乳状液的稠度系数(K)逐渐增大,而流变特性指数(n)逐渐减小;随着温度升高,K逐渐减小,而n逐渐增大。油包水乳状液黏度预测模型的最佳适用条件为:乳状液体积含水率0.30~0.60、温度30~60℃、乳状液黏度10~2000 mPa·s。该模型计算黏度值与实测值之间的平均相对偏差为8.1%,预测效果良好。

稠油水包油型乳状液黏度预测的改进模型

基于现有的水包油(O/W)型乳状液的混合黏度模型,采用实验和数值分析相结合的方法,综合考虑了稠油O/W型乳状液含油率、温度、剪切速率、表面活性剂种类及含量对黏度的影响,提出了一种黏度预测的改进模型。模拟结果表明,改进模型比原有的Rönningsen模型、Al-Roomi模型具有更高的计算精度,能够实现稠油O/W型乳状液实际黏度更加精准的预测。

油水界面活性聚合物驱采出液反相破乳剂研究进展

采用部分水解聚丙烯酰胺进行聚合物驱是应用最广泛的化学驱技术。为解决部分水解聚丙烯酰胺在高矿化度、高温水体内增黏效果差和难以注入低渗透率油藏的问题,聚合物驱中引入了带有亲油侧链且具有油水界面活性的改性聚丙烯酰胺代替普通部分水解聚丙烯酰胺,在改善高矿化度、高温和低渗透率油藏聚驱开发效果的同时,也减少了聚合物的用量及费用。注入油水界面活性聚合物的部分区块的采出液中O/W型原油乳状液稳定性高,造成采出水处理设施进水含油浓度大幅度增高,处理后回注的采出水含油浓度难以达到回注指标。为此分析了含油水界面活性聚合物驱的性质以及对O/W型乳状液的乳化和稳定作用,明确了今后反相破乳剂的研发应以非离子和阴离子药剂等与阴离子型油水界面活性聚合物不产生沉淀反应的药剂为主要方向。

单管集油工艺在超稠油区块高含水期的应用研究

超稠油随着蒸汽吞吐、蒸汽驱、SAGD开发,地下温场逐步形成,出井温度、综合含水率升高。传统的三管伴热工艺不仅能耗高,设施老化问题突出,并且已建的伴热规模无法满足新增生产井产出液的集输需求。为了降低地面系统整体能耗,优简站场布局,开展了高含水期超稠油单管集输技术研究,取消三管伴热高能耗流程,根据区块生产特点及已建地面工艺系统情况,结合含水油流变特性,进行温度、含水率、流量及集输半径4方面因素对单管集油工艺影响的边界条件分析,得出不同工况下的界限曲线,提出解决单井停产时原油粘壁难题的可实施方案。将理论应用于现场试验,形成井场内环状串接集油+井场间合并集输工艺模式,偏远低产井通过电加热方式改善集输条件,实现高含水期超稠油单管集油,经济效益显著,为全区块优化工艺提供可靠依据。

原油乳状液破乳方法的研究进展

为了解决原油乳状液油水分离难的问题,采油工厂常采用各种各样的方法对其进行破乳,对物理破乳法、生物破乳法、化学破乳法、化学和物理相结合的破乳方法等类型的破乳方法进行了介绍,并概括了它们各自的特点,对乳状液破乳研究具有一定的指导意义。

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。