The aggregates of asphaltene and resin molecules play an important role in stabilizing heavy crude oil. Although many experiments are applied to investigate the complex aggregating structure of asphaltene and resin molecules in heavy crude oil, those microstructure and properties are still not clear at the molecular level. As another auxiliary tool, molecular dynamics (MD) simulation can be used to simulate the behavior of asphaltene and resin in the heavy oil droplet or emulsified oil droplet. The simulation results showed the following: (i) Asphaltene and resin molecules can form a netlike structure in heavy oil through face-to-face or edge-to-face stacking interaction, and the aggregating structure is considered to be the main reason that heavy crude oil has high viscosity. (ii) When surfactant molecules were added to the heavy oil phase, the asphaltene molecules moved to the center of emulsified oil droplet from the oil/water interface. The adsorption of surfactant molecules at the interface resulted in an increase in the hydrophilic surface area of the oil droplet. We think that the changed hydrophilicity of emulsified oil droplet is the key to the viscosity reduction of heavy oil. (iii) The steered MD simulation can prove that the interaction among asphaltene and resin molecules becomes fragile in emulsified heavy oil droplet, and it indicates that the added surfactant molecules are beneficial to the viscosity reduction in crude oil.

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十二烷基硫酸钠在乳化重油液滴中沥青质和树脂聚集行为的分子动力学研究

沥青质和树脂分子的聚集体在稳定重质原油中起重要作用。尽管许多实验被用来研究重质原油中沥青质和树脂分子的复杂聚集结构，但在分子水平上仍不清楚那些微观结构和性质。作为另一个辅助工具，分子动力学（MD）模拟可用于模拟重油滴或乳化油滴中沥青质和树脂的行为。仿真结果表明：（i）沥青质和树脂分子可以通过面对面或边对面的堆积相互作用在重油中形成网状结构，而聚集结构被认为是重油的主要原因。原油具有高粘度。（ii）将表面活性剂分子添加到重油相中时，沥青质分子从油/水界面移动到乳化油滴的中心。表面活性剂分子在界面上的吸附导致油滴的亲水表面积增加。我们认为，乳化油滴亲水性的变化是降低稠油粘度的关键。（iii）转向MD模拟可以证明乳化重油滴中沥青质和树脂分子之间的相互作用变得脆弱，表明添加的表面活性剂分子有利于降低原油的粘度。我们认为，乳化油滴亲水性的变化是降低稠油粘度的关键。（iii）转向MD模拟可以证明乳化重油滴中沥青质和树脂分子之间的相互作用变得脆弱，表明添加的表面活性剂分子有利于降低原油的粘度。我们认为，乳化油滴亲水性的变化是降低稠油粘度的关键。（iii）转向MD模拟可以证明乳化重油滴中沥青质和树脂分子之间的相互作用变得脆弱，表明添加的表面活性剂分子有利于降低原油的粘度。