Rheological and physicochemical characterization of UAE crude oil

This study focuses on the rheological and physiochemical characterization of three samples of light crude oil and fuel oil from the United Arab Emirates. The dependence of density on temperature ranging from 20 to 200°C was determined. Also, the impact of temperature was investigated on viscosity, shear stress τ, shear rate, yield stress, and thixotropic behavior, and characterized by the Haake RheoStress. The exponential decrease of viscosity over temperature range was modeled using Arrhenius equation. The shear stress–viscosity data revealed that crude oil A solely exhibited Newtonian behavior while crude oils B and C and fuel oil followed the Herschel-Bulkley model.     

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 C. The crude oil exhibited a shear thinning behavior at all the temperatures. The strongest shear thinning was observed at 20 C. 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-in-water emulsion to water-inoil emulsion occurred at 30 % 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 around350 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.     

稠油乳状液的流变性试验研究

用四种不同的粘性原油乳状液进行了乳状液流变性的研究。结果表明，剪切应力与剪切速率的关系和液滴尺寸大小密切相关，视粘度和非牛顿性随液滴尺寸减小而增大。大部分乳状液在低剪切速率下（＜５０Ｓ－１）剪切变稀，当剪切速率超过５００ｓ－１时呈现牛顿流体性质。因此．液滴尺寸是乳状液流变性研究中的重要因素。     

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART I WITH AND WITHOUT POUR POINT DEPRESSANT ADDITIVES

The yield stress, plastic viscosity and apparent viscosity and the dependence of the latter on the shear rate have been studied at different temperatures below pour point of Lingala (Krishna-Godavari basin, Eastern coast), Duliajan (Eastern region of Assam), Rava (Godavari basin) and Bombay-High (off-shore western region) indigenous crude oils

Four different commercial pour point depressant additives have been used to study their effects on the pour point, yield stress and plastic viscosity

From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point, and crude base composition has a small effect. However, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the liquid matrix. As the temperature is lowered both the yield stress and plastic viscosity increase in case of each crude oil. However, the magnitude is dependent on the nature of the crude oil. With pour point depressant additives, the yield stress and plastic viscosity are decreased and this decrease is a function of nature of the liquid matrix of the crude oil and concentration of the additive     

微观液滴分布对含蜡原油乳状液流变性的影响

通过显微镜观察并拍摄原油乳状液的微观结构图像,研究了乳状液体系分散相液滴大小及分布规律,以及微观液滴分布对乳状液体系流变性的影响机理。W/O型原油乳状液中含水率增加,引起内相液滴个数增多,小液滴所占的比例减小,相对大的液滴所占的比例增大;搅拌转速的增大,使体系内相液滴个数增多,平均液滴直径减小。通过测试在固定搅拌条件下制备的不同含水率的3种含蜡原油乳状液在原油凝点附近温度屈服特性和触变性等流变特性,可以发现随含水率的增大,乳状液体系屈服应力增大、触变性增强,且含水率越高,变化的趋势越明显。通过测试不同搅拌转速下制备的含水率为30% 的原油乳状液在原油凝点附近温度的触变性,可以看出随搅拌转速的增大,体系经受同等剪切速率剪切时对应的剪切应力增大、触变性增强。进一步建立了屈服应力与测试温度、含水率之间的关系式,其平均相对误差为9.83%。     

LOW TEMPERATURE FLOW CHARACTERISTICS OF SOME WAXY CRUDE OILS IN RELATION TO THEIR COMPOSITION : PART I WITH AND WITHOUT POUR POINT DEPRESSANT ADDITIVES

ABSTRACT

The yield stress, plastic viscosity and apparent viscosity and the dependence of the latter on the shear rate have been studied at different temperatures below pour point of Lingala (Krishna-Godavari basin, Eastern coast), Duliajan (Eastern region of Assam), Rava (Godavari basin) and Bombay-High (off-shore western region) indigenous crude oils

Four different commercial pour point depressant additives have been used to study their effects on the pour point, yield stress and plastic viscosity

From this study it has been found that wax concentration and its composition are primarily responsible for the variation in the pour point, and crude base composition has a small effect. However, the response of the pour point depressant additive in effecting the change in the pour point is primarily governed by the liquid matrix. As the temperature is lowered both the yield stress and plastic viscosity increase in case of each crude oil. However, the magnitude is dependent on the nature of the crude oil. With pour point depressant additives, the yield stress and plastic viscosity are decreased and this decrease is a function of nature of the liquid matrix of the crude oil and concentration of the additive     

W/O型含蜡原油乳状液胶凝体系的屈服特性

在恒定剪切应力和剪切应力线性增加2种加载模式下,研究了油包水（W/O）型含蜡原油乳状液胶凝体系在凝点温度附近的屈服行为。以原油乳状液胶凝体系的屈服应变、屈服剪切速率为特征量,分析了剪切应力加载条件、加载量和胶凝体系含水率对含蜡原油乳状液胶凝体系屈服特性的影响规律。引用屈服应变比例系数的概念,分析了不同恒温静置时间后含蜡原油乳状液胶凝体系结构恢复程度及其影响因素。研究发现：屈服应变可作为W/O型含蜡原油乳状液胶凝体系屈服的判据;增大原油乳状液胶凝体系含水体积分数,屈服应变增大,屈服剪切速率减小,体系恢复度增加。增大剪切应力加载量或剪切应力增加速率,原油乳状液胶凝体系屈服剪切速率增大,该体系的结构恢复程度变差。     

酸化-混凝-催化氧化联合处理钻井废液研究

采用灰色关联熵分析法研究了胜利油田稠油黏度与其极性四组分含量和极性组分偶极矩的关联。同时通过改变实验油样乳状液的含水率及温度,探究了稠油组成性质与其乳状液反相点的关联。结果表明：稠油极性四组分含量与其黏度关联度的顺序是：沥青质〉胶质〉芳香分〉饱和分;稠油极性组分偶极矩与其黏度的关联度顺序是：沥青质〉胶质〉芳香分。随着稠油胶质、沥青质含量的增大,油水界面张力的降低、油滴Zeta电位绝对值的增大,乳状液含水率的反相点及温度的反相点逐渐升高。     

储层条件下的含蜡原油流变性研究

为研究含蜡原油在储层条件下的流变性,应用高压拈度计,在储层压力条件下开展了原油流变性实验。结果表明：在较低的温度条件下,含蜡原油的拈度随剪切速率增大而减小,且起初在一定的剪切速率范围内减幅较大,随后减幅越来越小;随着温度的降低,含蜡原油的表观拈度、拈流活化能及稠度系数增大,非牛顿指数减小,流变特性越来越偏离牛顿流体;采用非牛顿指数、稠度系数、拈流活化能和结构拈度指数等4项参数,能较全面地表征储层条件下含蜡原油的流变性。     

VISCOSITY BEHAVIOR: CORRELATION OF WATER-IN-OIL EMULSIONS IN PRESENCE OF SOLIDS

This is a study of viscosity behavior of oil-water emulsions-solid mixtures. It uses three oils in the presence of different volume fractions (0.005 - 0.02) of fine solids that have different affinities for water. It has been revealed that suspensions and emulsion-solid mixtures of each oil have identical viscosity at the same shear rate. This is an indication that emulsions behave as continuous phase, whilst solids behave as dispersed phase. Consequently, it is possible to correlate the relative viscosity (η_r) data with formulas available in literature for predicting the viscosity of suspensions and emulsions. Relative viscosity is defined as the emulsion-solid mixture viscosity over the pure emulsion viscosity. It has also been found out that Richardson equation [η_r = exp(a ϕ_s)] with values of 80 and 87 for the parameter a, fits the relative viscosity data of the two light oils used and the heavy one, respectively. The emulsion-solid mixtures prepared in the presence of both hydrophobic and hydrophilic solids were correlated by the same model. Furthermore, The viscosity of pure emulsions of two of the oils studied was found to fit both Krieger's hard sphere model and Roscoe's model but the third oil was found to fit Eilers' model.     

VISCOSITY BEHAVIOR: CORRELATION OF WATER-IN-OIL EMULSIONS IN PRESENCE OF SOLIDS

This is a study of viscosity behavior of oil–water emulsions-solid mixtures. It uses three oils in the presence of different volume fractions (0.005 – 0.02) of fine solids that have different affinities for water. It has been revealed that suspensions and emulsion-solid mixtures of each oil have identical viscosity at the same shear rate. This is an indication that emulsions behave as continuous phase, whilst solids behave as dispersed phase. Consequently, it is possible to correlate the relative viscosity (η_r) data with formulas available in literature for predicting the viscosity of suspensions and emulsions. Relative viscosity is defined as the emulsion-solid mixture viscosity over the pure emulsion viscosity. It has also been found out that Richardson equation [η_r = exp(a ?_s)] with values of 80 and 87 for the parameter a, fits the relative viscosity data of the two light oils used and the heavy one, respectively. The emulsion-solid mixtures prepared in the presence of both hydrophobic and hydrophilic solids were correlated by the same model. Furthermore, The viscosity of pure emulsions of two of the oils studied was found to fit both Krieger's hard sphere model and Roscoe's model but the third oil was found to fit Eilers' model.     

Investigation of non-Newtonian flow characterization and rheology of heavy crude oil

The heavy crude oil exhibits a non-Newtonian shear thinning behavior over the examined shear rate. The viscosity of the heavy crude oil decreases about 15.6% when the temperature increased from 30 to 60°C. Heavy crude oil was blended with the aqueous solution of surfactant and saline water in different volumetric proportions of NaCl, and Na₂CO₃ solution mixtures. The addition of 50% of the mixture to the heavy crude oil causes a strong reduction in the viscosity, about 67.5% at 60°C. The heavy crude oil fits the Power law model since it has the lowest average absolute percent error of 0.0291. The flow behavior index of the heavy crude oil reaches a value of 0.9305 at a temperature of 30°C and it increases to 0.9373 when the temperature raises 60°C, while the consistence coefficient decreases from 2.8811 to 2.3558.     

非牛顿稠油包水乳状液的剪切稀释性

以现场稠油和矿化水为工质,制备了多组不同微观液滴分布的W/O型乳状液,结合显微镜观察及测量分析,获得了对稠油包水乳状液微观液滴分布及非牛顿性的定量分析。结果表明,随微观液滴直径的减小,乳状液体系将具有更高的表观黏度,并表现出更强的剪切稀释性;结合颗粒雷诺数（η_r-N_Re,p 关系）,能够很好的表征剪切率及微观液滴分布对稠油包水乳状液剪切稀释性的共同影响。     

Change of Yield Stress of Daqing Crude Oil With Thermal and Shear History

Abstract

Daqing crude oil is a typical waxy crude oil with a wax content of 26.6 wt.% and a gel point of 32°C. The yield stress of waxy crude oils is an important property in the process calculation and flow safety analysis for heated oil pipeline. The Daqing crude oil was studied and the yield stress change with shear history was explored through simulation experiment of pipelining. It was found that the change of throughput variation or shear rate showed little effect on yield stress. There existed a peak yield stress on the relation curve of yield stress with final dynamic cooling temperature. The prediction model of yield stress for waxy crude oil under the condition of shutdown was developed and can be used to predict the yield stress of Daqing crude oil at certain heating temperature, final dynamic cooling temperature, and measurement temperature. For the 139 groups of yield stress data of Daqing crude oil from the simulation experiment of pipelining, the result of prediction with this model showed that the average relative deviation between the yield stress measured and predicted is 30.27%, and the coefficient of correlation is 0.9623.     

A New Unified Model for Predicting Non-Newtonian Viscosity of Waxy Crudes

Abstract

Viscosity determination in the non-Newtonian regime has always been a major problem in the oil industry. This is due to its dependence on the wax precipitated shear and thermal history of the crude oil. The present shear rate dependent viscosity model was developed by applying the theory of suspension rheology. This model is characterized by its capacity to predict viscosities of crude oils with different shear and thermal history and those containing petroleum-based diluents. Once viscosities at two temperatures above the wax appearance temperature (WAT) and apparent viscosity in the non Newtonian regime are known, viscosities or apparent viscosities at any temperature above the gel point can be determined by using the model together with the concentration of precipitated wax at the specified temperature. Verification of the model by using two Nigerian crudes with different shear and thermal histories and two crudes obtained from the literature shows that the model predicts viscosities with an average absolute deviation of 4.9%.     

Modeling of flow of oil-in-water emulsions through porous media

Formation and flow of emulsions in porous media are common in all enhanced oil recovery techniques.In most cases,oil-in-water(O/W) emulsions are formed in porous media due to oil-water interaction.Even now,detailed flow mechanisms of emulsions through porous media are not well understood.In this study,variation of rate of flow of O/W emulsions with pressure drop was studied experimentally,and rheological parameters were calculated.The pressure drop increases with an increase in oil concentration in the O/W emulsion due to high viscosity.The effective viscosity of the emulsion was calculated from the derived model and expressed as a function of shear rate while flowing through porous media.Flow of O/W emulsions of different concentrations was evaluated in sand packs of different sand sizes.Emulsions were characterized by analyzing their stability,rheological properties,and temperature effects on rheological properties.     

大庆原油与碱作用机理研究

 采用四组分分离法将大庆原油分离为饱和分、芳香分、胶质和沥青质，并用醇碱萃取法提取原油中的酸Ⅰ组分和酸Ⅱ组分。分别考察了各组分模拟油与水及碱体系的界面张力、界面剪切黏度，以及模拟油与碱长时间反应所形成的乳状液稳定性。结果表明，大庆原油中能降低油-水界面张力的主要活性组分是与碱反应较快的酸；对模拟油与碱体系形成的W/O型乳状液起稳定作用的主要组分是其中与碱反应较慢的、支链较多的大分子酸及酯类。大庆原油饱和分中存在着与碱发生慢反应的酯类。原油、原油组分模拟油与 碱反应初期，易形成O/W型乳状液，反应后期乳状液由O/W型向W/O型转变。醇碱萃取法只能萃取出与碱发生快速反应的酸组分，而不能将与碱反应较慢的相对分子质量较大的酸或酯类萃取出来。     

Influence of polymers on the stability of Gudao crude oil emulsions

The influence of different types and concentrations of polymers on the stability of Gudao crude oil emulsion was investigated by measuring the volume of water separated from the emulsions and the interfacial shear viscosity of the oil/water interfacial film. Experimental results indicate that the simulated water-in-oil emulsion with 40 mg/L of partially hydrolyzed polyacrylamide （HPAM） 3530S could be easily broken by adding demulsifier C and was readily separated into two layers. However, HPAM AX-74H and hydrophobically associating water-soluble polymer （HAP） could stabilize the crude oil emulsion. With increasing concentration of AX-74H and HAP, crude oil emulsions became more stable. Water droplets were loosely packed in the water-in model oil emulsion containing HPAM 3530S, but water droplets were smaller and more closely packed in the emulsion containing AX-74H or HAP. The polymers could be adsorbed on the oil/water interface, thereby increasing the strength of the interracial film and enhancing the emulsion stability.     

原油／碱－聚合物水溶液乳状液流变性研究

测定了不同含油率的大港羊三木原油／碱－聚合物水溶波乳状液的流变性，用七个流变方程对实测结果进行了曲线拟合，发现此乳状液服从Ｃａｓｓｏｎ方程，结合显微观察结果讨论并解释了乳状液粘度和ＣＡｓｓｏｎ方程参数随含油率和剪切速率变化的规律。     

Comparative studies of the rheological behavior and microstructural properties of emulsions (oil/distilled water phase) and (oil/Lias water phase)

Abstract

The rheological behavior of crude oil and their emulsions were investigated as a function of two water types (distilled water and the LIAS water). The focus of this work is to obtain more knowledge about the effect of LIAS water concentration, which used to maintain pressure and produced from production of crude oil in the oil fields Tin Fouye Tabankort-south Algeria, on the rheological properties of crude oil. The rheological parameters were measured by using AR-2000 rheometer at 15?°C under dynamic and shear testing conditions. The measured data were first classified into two groups for Newtonian and non-Newtonian fluids. Depends on the type and concentration of water, the non-Newtonian behavior was described in better way by the Casson, Power law and the Herschel–Bulkley models. The results indicated that the viscosity, the yield stress, the elastic modulus, (G′), the loss modulus, (G″), and the microstructure of the prepared emulsions not only varied with water concentration but also by water types.