双亲分子头部官能团对石油沥青质胶团分散性的影响Ⅱ.石油沥青质胶团形状、溶剂化程度与相互作用

为理解双亲分子对石油沥青质甲苯溶液巾沥青质胶团形状、溶剂化程度以及颗粒间相互作用的影响,测定了其甲苯溶液的黏度,采用Pals-Rhodes方程、Eiler方程、Kuhn-Kuhn方程和Leighton-Acrivos方程关联了黏度与体积分数之间的关系.由Pals-Rhodes方程得到的形状参数α和溶剂化参数K表明.在沥青质甲苯溶液中沥青质胶用为球形.添加双亲分子后其溶剂化程度增加,但其形状仍为球形.由Eiler方程分析表明,沥青质甲苯溶液添加双亲分子后,沥青质最大堆积体积分数ψ_m增加,说明沥青质胶团的分散度增加.由Kuhn-Kuhn方程计算所得沥青质甲苯溶液中沥青质颗粒的形状因子严重偏离球形,因未考虑溶剂化效应和颗粒间的相互作用,故与Pals-Rhodes方程得到的结果差别较大.由Leighton-Acrivos方程得到的相互作用系数表明,沥青质甲苯溶液添加双亲分子后,沥青质胶团之间的相互作用程度增加.     

双亲分子头部官能团对石油沥青质胶团分散性的影响Ⅰ.石油沥青质胶团尺寸

为认识含有不同头部官能团的双亲分子对沥青质胶团分散性的影响,测定了添加十二烷基苯磺酸(DBSA)、十二烷基苯酚(DP)和十二醇的沥青质甲苯溶液的黏度变化规律,通过线性拟合得到其特性黏度[η],进而计算得到无限稀释情况下沥青质胶团直径.同时,对比了添加双亲分子前后沥青质甲苯溶液的比浓黏度随沥青质浓度的增加速率和胶团直径的变化.结果表明,酸性较强的十二烷基苯磺酸易于在沥青质表面吸附,在高浓度时,甚至可以明显增加沥青质胶团的直径.十二烷基苯酚吸附量较小,不能明显改变沥青质胶团的大小,而十二醇较难在沥青质表面吸附,对沥青质溶液的黏度几乎没有影响.由此可以初步推断,双亲分子头部官能团的酸性越强,其与沥青质的作用越强,在沥青质表面吸附的越多,其抑制沥青质聚并的能力越强.     

双亲分子头部官能团对石油沥青质胶团分散性的影响

为认识含有不同头部官能团的双亲分子对沥青质胶团分散性的影响,测定了添加十二烷基苯磺酸(DBSA) 、十二烷基苯酚(DP)和十二醇的沥青质甲苯溶液的黏度变化规律,通过线性拟合得到其特性粘度,进而计算得到无限稀释情况下沥青质胶团直径。对比添加双亲分子前后,比浓黏度随浓度的增加速度和胶团直径的变化都表明：双亲分子头部官能团酸性越强,其与沥青质的作用越强,在沥青质表面吸附的越多。酸性较强的十二烷基苯磺酸在沥青质表面能形成多层吸附或者发生聚集,十二烷基苯酚只能形成单层吸附,而十二醇则对沥青质溶液的黏度几乎没有影响,可能没有发生吸附。     

双亲分子与石油沥青质作用的zeta电位

 为认识双亲分子与沥青质作用的机理,采用电泳光散射法测定了添加双亲分子前后沥青质溶液和渣油溶液zeta电位的变化,并由此计算了不同条件下胶团的电性斥力位能。实验结果表明,不同沥青质在甲苯溶液中的zeta电位的大小和电荷的正负性并不相同。zeta电位与沥青质的表面官能团组成有关外,双亲分子A在沥青质表面的吸附会改变沥青质胶团的zeta电位。可以推断,沥青质胶团在有机溶剂中所带的电荷来自电荷转移作用。双亲分子对不同渣油热反应的影响并不相同,说明沥青质胶团zeta电位与双亲分子端基官能团之间需要一定的匹配性。胶团间电性斥力位能不是影响沥青质胶体稳定性的主要因素。     

双亲分子稳定辽河沥青质的作用及其机理

 为认识双亲分子化合物对沥青质的稳定作用及稳定机理,采用X射线光电子能谱（XPS）分析了辽河沥青质颗粒表面杂原子官能团的类型和含量;采用紫外－可见光谱(UV-Vis)测定添加双亲分子前后沥青质甲苯－正庚溶液中沥青质浓度的变化,进而分析了不同双亲分子化合物对辽河沥青质的分散稳定作用;采用红外光谱(FT-IR)分析初步探讨了十二烷基苯磺酸（DBSA）对沥青质分散稳定作用的机理。结果表明,沥青质颗粒表面含氮官能团主要为碱性的吡啶氮官能团和弱碱性的吡咯氮官能团,含氧官能团主要为碳氧单键和碳氧双键结构,表面杂原子官能团的数量虽然较少,但为沥青质与双亲分子作用的关键因素;双亲分子头部官能团和沥青质颗粒表面杂原子之间的酸碱作用越强,其分散稳定沥青质的能力越强;DBSA通过其磺酸基官能团与沥青质颗粒表面的羟基和氨基形成分子间氢键而吸附在沥青质上。     

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。     

石油沥青质的热解化学

石油沥青质热分解之所以引起人们的兴趣,是由于沥青质在石油加工过程中易生成高产率的焦炭,并使催化剂失活。总的说来是认为,生焦化学包括热不稳定键的热解生成活性物质,然后进一步反应生成焦炭。本文的数据表明:初次反应生成分子量较低的产物,这些分子中氮的存在促进了键的断裂。其它诸如环烷系的芳构化与芳环系的最终缩聚等反应将导致焦炭的生成。一个重要的新发现是焦炭的生成并不经由直接缩合反应,而是通过初次反应生成分子量较低的产物,它们的芳香度高,并含有原始沥青质中大部分的氮(氧或硫)。     

石油沥青质的化学和物理─Ⅰ石油沥青质的定义和分离

石油沥青质是最重要的石油组分之一，它在石油的勘探、开发、储运、加工及重质石油产品利用方面有着重要作用．本文论述了石油沥青质的含义及分布沥青质的各种方法，详细讨论了使用溶剂分离沥青质的理论基础和各种影响因素。     

石油沥青质的化学和物理：Ⅳ.石油沥青质溶液的胶体化学

本文从胶体化学的角度讨论了石油青质的性质，评述了自１９２４年以来提出的各种沥青胶体模型，探讨了石油胶粒的形状和尺寸，形成机制以及沥青质粒子聚集的动力学行为。     

Investigation of Asphaltene Precipitation Process for Kuwaiti Reservoir

Abstract

As part of an Enhanced Oil Recovery (EOR) research program, Asphalting precipitation processes were investigated for a Kuwaiti dead oil sample using different hydrocarbons and carbon dioxide as precipitants at the ambient and high pressure of 3000 psig conditions. The hydrocarbons used as precipitants were ethane (C2), propane (C3), butane (C4), normal pentane (n-C5), normal hexane (n-C6), and normal heptane (n-C7). The equipment used for this investigation was a mercury-free, variable volume, fully visual JEFRI-DBR PVT system with laser light scattering. The minimum critical value of precipitants concentration for the oil sample has been identified at the ambient and high-pressure conditions for each precipitant. Our investigation has revealed that for this oil sample the most powerful asphaltene precipitant were CO₂ followed by C2, C3, C4, n-C5, n-C6, and n-C7. Moreover, the effect of pressure and temperature on the asphaltene precipitation has been investigated experimentally for CO₂, n-C5, n-C6, and n-C7. The precipitation and redissolution of asphaltene upon the addition and removal of CO₂ and light alkanes (C2–C4), at 3000 psig and ambient temperatures, have shown evidence of reversibility of asphaltene precipitation. A comprehensive fluid characterization analysis for the oil sample has been performed including, physical properties of crude oil, compositional, molecular weight (Mw), and SARA analyses. Advanced analytical techniques such as 1H and 13C NMR and IR spectrometers have been utilized to investigate the molecular structure of the asphaltene for this sample. It was concluded that the asphaltene molecules for this oil contain 120 total aromatic carbons with 42 aromatic rings, 114 naphthenic rings, and 5–7 sets of condensed aromatic rings.     

A Thermodynamic Model for the Prediction of Asphaltene Precipitation

Abstract

Asphaltene precipitation in reservoirs, wells, and facilities can have a severe and detrimental impact on the oil production. Due to the extreme chemical complexity of the asphaltene and crude oil and the lack of comprehensive experimental data, the modeling of asphaltene precipitation in crude oil remains as a challenging task. In this article, a compositional thermodynamic model was developed to predict asphaltene precipitation conditions. The proposed model is based on a cubic equation of state with an additional term to describe the association of asphaltene molecules. Extensive testing against the literature data, including asphaltene precipitation from crude oil and solvent injection systems, concludes that the proposed model provides reasonable predictive results.     

Experimental investigation of asphaltene deposition mechanism during oil flow in core samples

Asphaltene deposition is an issue that has received much attention since it has been shown to be the cause of major production problems in enhanced oil recovery processes. Asphaltenes are heavy oil components which, under certain conditions, precipitate and the solid phase they form may deposit in the porous media of the oil reservoir. All proposed remediation techniques have proven costly and not highly effective, so prevention becomes the only way to counteract the problem. Revelation of the deposition mechanism and determination of the parameters they affect it are necessary in order to devise reliable prevention strategies. In this work, an experimental effort is made to investigate the deposition process in core samples, under simulant and realistic flow conditions. The main experimental tools utilized for this purpose are permeability measurements, analysis of asphaltene concentration, pore structure characterization techniques and Soxhlet extraction for the determination of the deposited asphaltenes. Both dead and reservoir oils are used as well as cores of various permeabilities and pore structure characteristics.     

几种原油降凝降粘剂作用机理的红外光谱和X射线衍射研究

详细研究了从大庆、江汉、冀东原油分离出的石蜡、胶、沥青质用降凝降粘剂处理后红外特征吸收峰和Ｘ射线衍射峰的变化。由红外数据证实，降凝剂分子与石蜡分子发生共晶是原油降凝作用的主要机理。由红外和Ｘ射线衍射数据得出结论；降粘剂破坏胶质、沥青质分子平面重叠的聚集体，使聚集结构变疏松，聚集有序性降低，是原油降粘作用的机理。     

磁场响应形状记忆聚合物复合材料的研究进展

磁场响应形状记忆聚合物(SMP)复合材料(MSC)是以SMP为基体树脂、磁性粒子为填料的一类复合材料。MSC的磁场响应原理:磁性粒子在交变磁场下产生热量,SMP因受热而产生相转变,从而实现了材料的形状回复。概述了SMP种类、外加磁场和磁性粒子对MSC磁场响应性的影响,重点阐述了磁性粒子的粒径、种类及其含量对MSC磁场响应性的影响。概括了MSC的研究现状和进展,展望了其应用前景。     

MOLECULAR SIZE AND STRUCTURE OF ASPHALTENES

Fluorescence depolarization measurements are used to determine the size of asphaltene molecules and of model compounds for comparison. Mean molecular weights of 750 amu have been found for petroleum asphaltenes. A strong correlation is established between the size of fused rings in asphaltene molecules and the overall size of these molecules, showing that asphaltenes have one or perhaps two fused ring systems per molecule. Coal asphaltene molecules are found to be much smaller than petroleum asphaltenes.     

Effects of Catalyst Properties on Asphaltenes Composition During Hydrotreating of Heavy Oils

Three NiMo commercial catalysts were used for carrying out hydrotreating (HDT) experiments in a high-pressure pilot plant. Maya crude oil was employed as HDT feed. All hydrotreated products and their corresponding precipitated asphaltenes fractions were characterized by elemental analysis and metals contents. Extraction of asphaltenes was carried out according to the method described in ASTM D-3279. It was observed from our characterization results that while nitrogen and metals content in asphaltenes increase sulfur decrease as the reaction temperature is increased. This different behavior was attributed to the localization of each heteroatom in the asphaltene molecule. Pore size of catalysts showed the major influence on hydrotreated product asphaltenes composition.     

Challenges Inherent in the Development of Predictive Deposition Tools for Asphaltene Containing Hydrocarbon Fluids

The correlation and prediction of deposit formation are at the core of flow assurance, risk assessment, and other reservoir fluid management issues and are equally important for heavy oil or bitumen partitioning and upgrading. Asphaltene deposition in particular is a key topic in both sectors. Hydrocarbons from condensate-rich reservoir fluids to bitumen + diluent mixtures share constituents, from asphaltenes and resins to pentane, and can all be classified as asymmetric from a phase behavior perspective. The phase dia-grams for these asymmetric fluids are characterized by zone of four-phase behavior surrounded by three-phase and two-phase regions in both pressure-composition at constant temperature, and pressure-temperature at constant composition diagrams. Adherent asphaltenic solid and liquid deposits only arise within some multiphase zones. Zones such as the SL1, SL1V, L1L2V, and L1L2 are prone to the production of adherent asphaltenic deposits particularly when combined with intermittent or laminar flow. By incorporating incomplete approaches prevalent in both sectors into qualitative four component phase diagrams, one can illustrate key aspects of the phase diagrams for the entire range of fluids, as well as the challenges faced with respect to the prediction of specific phase behaviors. In this article we present and illustrate some of these challenges and propose a path toward their resolution.