STRUCTURE, INTERACTION AND PHASE TRANSITION OF VACUUM RESIDUE IN APOLAR SOLVENTS

Structure, Interaction, and phase transition of a vacuum residue fractions In various apolar solvents were Investigated, using viscosity measurements and small angle neutron scattering. Both light and heavy ended fractions form colloidal particles of spherical shape with average sizes of -40 and -60 A respectively. The size distributions follow a Schultz distribution function approximately. Rheological studies of these fractions indicated significant particle solvation. The solvation mechanism is through association of the solvent molecules with individual VR colloids, instead of through solvent entrapment between agglomerated colloids. The viscosity, as a function of temperature, suggested a glass-like transition at approximately 254 K for the heavy ended fraction at 0.5 volume fraction. The small angle neutron scattering measurements confirmed the colloidal structure determined from rheological study. It also provided the information about the total colloids/solvent Interfacial area, from which we found that VR colloids have a rough surface     

Investigation of Molecular Weight and Aggregation of Asphaltenes in Organic Solvents Using Surface Tension Measurements

Abstract

The physico-chemical behavior of asphaltene is very useful to assist prediction and control the mechanisms of asphaltene deposition during the production of petroleum fluids. It has been realized that the first step in the formation of precipitated asphaltene particles is the self-aggregation mechanism to form colloidal particles or pseudo-micelles in several solvents. In this work, the critical micelle concentration (CMC) of two asphaltene fractions extracted from vacuum residues (VR) were obtained by surface tension measurements, using aromatic solvents. The molecular weight (1094-565 g/mol), calculated from average radii of the asphaltene molecules adsorbed at the air–solvent interface, are also in agreement with the values for small aggregates reported using small angle X-ray scattering.     

Investigation of Molecular Weight and Aggregation of Asphaltenes in Organic Solvents Using Surface Tension Measurements

The physico-chemical behavior of asphaltene is very useful to assist prediction and control the mechanisms of asphaltene deposition during the production of petroleum fluids. It has been realized that the first step in the formation of precipitated asphaltene particles is the self-aggregation mechanism to form colloidal particles or pseudo-micelles in several solvents. In this work, the critical micelle concentration (CMC) of two asphaltene fractions extracted from vacuum residues (VR) were obtained by surface tension measurements, using aromatic solvents. The molecular weight (1094-565 g/mol), calculated from average radii of the asphaltene molecules adsorbed at the air-solvent interface, are also in agreement with the values for small aggregates reported using small angle X-ray scattering.     

THE COLLOIDAL STRUCTURE OF CRUDE OILS AND SUSPENSIONS OF ASPHALTENES AND RESINS

ABSTRACT

A better understanding of colloidal macrostructure of the heavy petroleum products and their complex fractions is of great importance in the context of industrial problems that arise during the crude oil production, refining and transport. Much effort has been devoted to the chemical structure studies, but there is a need for more precise data regarding parameters that characterize those complex systems. For instance, the molecular weight of heavy molecules, the composition and size of aggregates formed during the industrial processing and their evolution upon the variation of temperature, pressure and with the addition of solvent have not been well known. In this paper we present new results obtained using several powerful techniques. Scattering methods (using X-rays and neutrons) are applied to study both the fractionated products (asphaltene and resin solutions in more or less good solvents) and the real systems (Safaniya vacuum residue). The lamellar structural model for asphaltenes and resins is confirmed and the molecular weight of these species determined using a polydisperse size distribution. Discussion is presented concerning the specificity of X-ray and neutron scattering : X-ray experiments are more sensitive to the aromatic-rich regions, whereas the neutron scattering data provide information about all the particle volume. Viscosimetry measurements provide information on the molecular shape of asphaltene and confirm the disk-like model. Critical micellar concentration has been obtained using Vapour Pressure Osmometry (VPO) for asphaltene suspensions in toluene and in pyridine. The resin molecules are smaller than asphaltenes, and appear to be a good solvent for asphaltenes. One of the major conclusions of this work is the wide-spread presence of density heterogeneities in diluted solutions of asphaltenes and resins as well as in the pure product (Safaniya vacuum residue). This was deduced from the scattering experiments and cryo-scanning electron microscopy data. The heating effects. were studied: a temperature increase leads to the decrease of molecular weight, but heterogeneities remain present. The structure of vacuum residue exhibits large density fluctuations which are thermally stable. These dense regions remain connected into a network up to 393°K and determine the yield value of the rheological behaviour.     

THE COLLOIDAL STABILITY OF CRUDE OILS AND CRUDE OIL RESIDUES

ABSTRACT

A crude oil and three residues of the crude oil processing were investigated by determination of flocculation points of both the product solutions and the original products. Diverse analytical methods were used for characterizing products and their fractions. The evaluation of results was performed by the theory of regular solutions and its extension by Hansen. It was found, that the colloidal disperse phase shows a behaviour similar to that of polymer solutions. The conditions of the destabilization of the colloids can be defined by the critical Flory-Huggins interaction parameter. The solvation and the low soluble part of the asphaltenes have the greatest influence on the colloidal stability. The lowest stability is found for the visbreaking residue. The influence of the crude oil distillation on the colloidal stability is not significant.     

基于特性黏度法计算沥青质胶团直径和溶剂化效应——分散体系活化状态表征

在委内瑞拉常压渣油中添加不同比例十八醇,考察十八醇对强化减压蒸馏效果的影响。结果表明,十八醇具有良好强化效果,最大蜡油净增收率为4.01%。测定渣油(沥青质)-甲苯溶液的黏度,根据Einstein黏度定律和Pals-Rhodes方程,计算得到了沥青质胶团直径D和溶剂化参数K,结果表明,特性黏度法测得的沥青质尺寸为沥青质胶核外吸附-溶剂化层的直径,其数值受溶剂化效应的影响,测定渣油-甲苯溶液黏度可以表征渣油体系中沥青质胶团尺寸。对于添加了十八醇的渣油体系,其沥青质胶团直径减小、溶剂化效应降低,变化趋势与减压蜡油净增收率有良好的对应关系,可以采用特性黏度法计算沥青质胶团直径和溶剂化效应,来预测石油分散体系的活化状态。     

THE COLLOIDAL STRUCTURE OF CRUDE OILS AND SUSPENSIONS OF ASPHALTENES AND RESINS

A better understanding of colloidal macrostructure of the heavy petroleum products and their complex fractions is of great importance in the context of industrial problems that arise during the crude oil production, refining and transport. Much effort has been devoted to the chemical structure studies, but there is a need for more precise data regarding parameters that characterize those complex systems. For instance, the molecular weight of heavy molecules, the composition and size of aggregates formed during the industrial processing and their evolution upon the variation of temperature, pressure and with the addition of solvent have not been well known. In this paper we present new results obtained using several powerful techniques. Scattering methods (using X-rays and neutrons) are applied to study both the fractionated products (asphaltene and resin solutions in more or less good solvents) and the real systems (Safaniya vacuum residue). The lamellar structural model for asphaltenes and resins is confirmed and the molecular weight of these species determined using a polydisperse size distribution. Discussion is presented concerning the specificity of X-ray and neutron scattering : X-ray experiments are more sensitive to the aromatic-rich regions, whereas the neutron scattering data provide information about all the particle volume. Viscosimetry measurements provide information on the molecular shape of asphaltene and confirm the disk-like model. Critical micellar concentration has been obtained using Vapour Pressure Osmometry (VPO) for asphaltene suspensions in toluene and in pyridine. The resin molecules are smaller than asphaltenes, and appear to be a good solvent for asphaltenes. One of the major conclusions of this work is the wide-spread presence of density heterogeneities in diluted solutions of asphaltenes and resins as well as in the pure product (Safaniya vacuum residue). This was deduced from the scattering experiments and cryo-scanning electron microscopy data. The heating effects. were studied: a temperature increase leads to the decrease of molecular weight, but heterogeneities remain present. The structure of vacuum residue exhibits large density fluctuations which are thermally stable. These dense regions remain connected into a network up to 393°K and determine the yield value of the rheological behaviour.     

重油分级催化裂化反应性能

 利用小型固定流化床实验装置,对重油中不同馏程范围馏分裂化性能进行研究,发现重油中存在反应性能差异明显的两类馏分,且在减压渣油中仍含有部分优质馏分,依此采用分级方法将重油分为优质、劣质裂化原料。实验对比了各分级点分级后重油的催化裂化产物分布,也对比了重油分级前后催化裂化反应产物分布的变化。结果表明,适当提高分级点温度,将减压渣油中的一部分馏分切入优质原料,通过分别裂化可以改善重油整体的产物分布,并确定了长庆、济南重油适宜的分级点分别在500~540℃和500~520℃范围。分级后针对不同性质原料匹配各自的反应区间,重油整体的轻质油收率提高,焦炭和干气的收率降低;且随着催化裂化原料掺炼渣油比例的增加,采用重油分级催化裂化提高目的产物的优势越明显。     

胜利管输稠油油溶性降黏剂的研制

中国石化石油化工科学研究院针对胜利稠油的组成和胶体结构特点,研制了新型油溶性降黏剂RPJN-SL。在加剂质量分数为2%、温度为50 ℃、剪切强度为200 r/min时,对5种胜利稠油的降黏率均大于55%,其中对单56-13-19稠油的降黏率高达73.6%;激光光散射、X射线衍射研究结果表明,降黏剂RPJN-SL对沥青质、胶质聚集体胶团具有显著的分散作用,使胶团尺寸大幅减小,并降低沥青质聚集体结构的有序性,从而削弱沥青质分子间相互作用力,形成分散程度更高、内部作用力更弱的体系,使稠油黏度大幅降低;降黏剂RPJN-SL的降黏效果基本不受温度变化的影响,并具有较好的抗剪切能力,可满足现有管输工艺条件使用要求。     

SWELLING OF ASPHALTENES

ABSTRACT

We report x-ray scattering measurements on asphaltenes and bitumen solutions, with attention to the concentrated regimes. We characterize the data in terms of a correlation length which is indicative of proximity to phase separation in a mixture, rather than the radius-of-gyration more indicative of individual colloids. By studying the behavior of the low-angle asphaltene peak on dilution, we show that asphaltenes swell. These results allow the drawing of a phase diagram with two regimes separated by a critical point: a colloidal regime, and a“ swollen asphaltene” regime, the latter being much larger.     

KINEMATIC VISCOSITY-TEMPERATURE BEHAVIOR OF HEAVY TBP-FRACTIONS (455°C+) OF ARABIAN CRUDE OILS

ABSTRACT

A generalized kinematic viscosity-temperature correlation for undefined liquid heavy petroleum fractions has been developed to represent the data for a wide range of temperature from 100°C to 200°C. The correlation is based on the experimental kinematic viscosity data of true boiling point fractions of four Arabian crude oils. The characterization property required for estimation is 50% boiling point. The proposed correlation fits the experimental data with an overall absolute error of 6.1%. Experimental measurements of kinematic viscosity of heavy true boiling point fractions of Arabian crude oils were also obtained in order to develop the proposed correlation.     

EFFECTS OF ASPHALTENE PRECIPITATION AND REPRECIPTION ON THE METAL-CONTAINING COMPOUNDS IN HEAVY RESIDUA

ABSTRACT

Boscan vacuum residuum (VR) has been separated into isooctane insoluble asphaltenes and isooctane soluble maltenes. The asphaltenes were dissolved in a minimum of toluene and were further separated by two additional reprecipitations using isooctane as the precipitating solvent. We examined the fractions, including the recovered isooctane soluble material, by size exclusion chromatography (SEC) with inductively coupled plasma (ICP) emission spectroscopy to determine the effects, if any, the reprecipitations have on the size distribution of the metal-containing compounds.

The asphaltene fractions show little change in size upon reprecipitation, but removal of a small amount of the metal components does occur. The first reprecipitation produces isooctane soluble material which is very similar in size to the original maltene fraction. However, the second reprecipitation removes small amounts of material in the size range of the asphaltenes. When the amounts were weight balanced, the resulting separation did little to effect the overall maltene and asphaltene size profiles.     

The Influence of Separated Fractions on Crude Oil Viscosity

Abstract

To solve the problem of heavy oil production, the properties of heavy oil and separated fractions of oil (saturates, aromatics, resin, asphaltene) were determined by the technologies of scanning electron microscope, energy spectrum analysis, and so on. The results show that the heavy oil viscosity decreased significantly with temperature increase and the turning point of temperature will change with different properties of heavy oil. The sequence of the influences of heavy oil components on its viscosity is: asphaltenes > resins > aromatics > saturates. The asphaltene is a primary influential factor among them. The contents of S, Cl, O, N, and mental elements (Ni, V) in Tahe heavy oil are relatively higher than that of ordinary crude oil. The viscosity of heavy oil will increase when the transition metal ions and organic heterocyclic elements form a stable complex. Now, there are few systematic studies on the influence of heavy oil separated fractions on its viscosity. The research will provide guidance for the exploitation technology of other heavy oil fields.     

稠油粘度与化学组成的关系

 测定了辽河油田、胜利油田、大港油田、大庆油田、渤海油田、中原油田、吐哈油田的25个不同黏度的稠油和油砂抽提物的黏度,并采用柱色谱法定量分析了它们的化学族组成,研究稠油黏度和其各化学组分之间的关系,提出了稠油黏度指标(Iv)概念。结果表明,稠油的黏度随非烃组分含量的增加而呈指数函数升高,即非烃组分对稠油黏度作正贡献,在相同含量下,贡献大小顺序依次是酸性非烃、沥青质、高极性非烃、中性非烃。稠油的黏度随饱和烃和芳烃组分含量的增加而呈指数函数降低,即饱和烃和芳烃组分对黏度作负贡献。稠油的黏度是其各化学组分共同贡献并相互作用的结果, 黏度指标(Iv)与稠油黏度之间具有良好的数学相关关系。     

Soil Microbial Degradation of Vacuum Residue

Abstract

The effect of microbial consortia on the alteration of petroleum residual structure and portions was studied, which can propose an alternative or complementary method for stringent upgrading heavy crude oil methods, which consist of heavy and complex hydrocarbons. Biological processing of petroleum heavy fractions and residua may provide an alternative or complementary process in refining heavy crudes—the dominant refinery feed in the future—with less severe process conditions and higher selectivity to upgrade heavy fractions of crude oil. The primary objective was to observe the ability of an indigenous bacterial consortium taken from a soil bellow the vacuum column contaminated with vacuum residue (VR) for several decades from the Tehran refinery distillation unit, in degradation of residua components. Enrichment with VR, as sole source of carbon and energy, is the selected biosurfactant-producing microbial consortium. The biodegradation of net VR using indigenous consortia from this specific ecosystem was studied. The considered period of biodegradation of these heavy hydrocarbons was remarkably shorter than usual studies. Bacterial growth and VR biodegradation ability of this consortium analyzed with SARA test in 20 days. Studying the inoculum size and aeration effect revealed the significance of oxygen for this consortia activity and the similarity of 7% and 5% inoculation on alteration percentage of alkane, aromatic, and asphaltene and resin in VR. Results study revealed a 30.4%, 6.9%, and 9.4% decrease in the asphaltene, aromatics, and saturated aliphatic contents of VR, respectively, in only 20 days in 30°C at 150 rpm.     

THE COLLOIDAL STABILITY OF CRUDE OILS AND CRUDE OIL RESIDUES

A crude oil and three residues of the crude oil processing were investigated by determination of flocculation points of both the product solutions and the original products. Diverse analytical methods were used for characterizing products and their fractions. The evaluation of results was performed by the theory of regular solutions and its extension by Hansen. It was found, that the colloidal disperse phase shows a behaviour similar to that of polymer solutions. The conditions of the destabilization of the colloids can be defined by the critical Flory-Huggins interaction parameter. The solvation and the low soluble part of the asphaltenes have the greatest influence on the colloidal stability. The lowest stability is found for the visbreaking residue. The influence of the crude oil distillation on the colloidal stability is not significant.     

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。     

GENERALIZED KINEMATIC VISCOSITY-TEMPERATURECORRELATION FOR UNDEFINED PETROLEUM FRACTIONS OF IBP – 95°C TO 455°C+ BOILING RANGES

ABSTRACT

A generalized kinematic viscosity-temperature correlation for undefined petroleum fractions of all boiling ranges including 455^+°C fractions have been developed to represent the data for a wide range of temperature from 30 to 200°C. The correlation is based on experimental kinematic viscosity data for twenty TBP fractions of Arab heavy, Arab medium, Arab light and Arab extra-light crude oils. The proposed correlation has been found to fit all the eperimental data consisting of 248 measurements of the kinematic viscosity with an overall average absolute deviation of 9.07% compared to 15.47% given by ASTM method.     

不同性质油品对渣油胶体稳定性的影响

向绥中36-1常压渣油中分别加入催化裂化油浆和减四线抽出油,研究了其对渣油胶体稳定性的影响。结果表明,加入两种油品后,体系的稳定性均呈下降趋势;不同油品对渣油胶体稳定性的影响程度不同,加入减四线抽出油后体系的稳定性比加入催化裂化油浆时高。从SARA组成、极性两方面考察了不同性质油品对混合体系胶体稳定性的影响。结果表明,SARA组分的变化对混合体系的胶体稳定性有影响,但不是影响其稳定性的主要因素,组分极性上的差距是造成混合体系稳定性变化的主要原因。     

原油减压渣油馏分的油-水界面性质Ⅳ.大庆减压渣油馏分的油-水界面粘度

采用剪切界面粘度仪考察了大庆减压渣油超临界馏分(简称大庆减渣馏分)的油-水界面粘度。研究结果表明，大庆减渣馏分油-水界面粘度随馏分的增重、油相中值分质量分数的增加以及水相中盐含量的增加而增大，随剪切速率的增大而降低。大庆减渣馏分中蜡含量多。对馏分的油-水界面粘度的影响大，油-水界面粘度受馏分中界面活性物质(胶质、沥青质)和蜡的共同影响。轻馏分油-水界面粘度随油相中芳烃含量的增加而增大。当油相煤油与苯体积比为1：1时，重馏分油-水界面粘度最大。碱性条件下，馏分油-水界面粘度最低。酸性条件对轻、重馏分的油-水界面粘度的影响不同，随着酸度的升高，轻馏分的油-水界面粘度下降，重馏分的油-水界面粘度上升。