石油学报 ›› 2020, Vol. 41 ›› Issue (5): 592-603.DOI: 10.7623/syxb202005008

• 油田开发 • 上一篇    下一篇

沥青质在高定向热解石墨表面络合机制的分子动力学模拟

李晔帆, 张迎春, 刘显东, 张弛, 陆现彩   

  1. 南京大学地球科学与工程学院内生金属矿床成矿机制研究国家重点实验室 江苏南京 210093
  • 收稿日期:2019-08-06 修回日期:2020-04-19 出版日期:2020-05-25 发布日期:2020-06-08
  • 通讯作者: 刘显东,男,1982年1月生,2004年获南京大学学士学位,2009年获南京大学博士学位,现为南京大学地球科学与工程学院教授,主要从事计算地球化学、计算矿物学研究。Email:xiandongliu@nju.edu.cn
  • 作者简介:李晔帆,男,1996年3月生,2017年获太原理工大学学士学位,现为南京大学地球科学与工程学院硕士研究生,主要从事计算地球化学研究。Email:1106310044@qq.com
  • 基金资助:

    国家自然科学基金项目(No.41872041,No.41425009)资助。

Molecular dynamics simulation of complexation of asphaltenes on the surface of highly oriented pyrolytic graphite

Li Yefan, Zhang Yingchun, Liu Xiandong, Zhang Chi, Lu Xiancai   

  1. State Key Laboratory for Mineral Deposits Research, School of Earth Science&Engineering, Nanjing University, Jiangsu Nanjing 210093, China
  • Received:2019-08-06 Revised:2020-04-19 Online:2020-05-25 Published:2020-06-08

摘要:

沥青质在固体表面的络合机制是解决剩余油开采难题的重要理论基础。为了给聚集抑制剂和表面活性剂的开发提供理论依据,采用分子动力学模拟,系统研究了沥青质在高定向热解石墨表面附着、聚集的特征。通过计算表面吸附过程中沥青质的自由能变化,基于Yen-Mullins模型的定量判据,结合沥青质平均相互作用分子数和分子密度分布,定量分析了沥青质在固-液界面体系与溶液体系中聚集作用的差异。分子动力学模拟分析表明,固体表面会降低沥青质的聚集程度,加快聚集过程中的阶段分化,具体包括4个阶段的界面过程:①沥青质覆盖固体表面并逐渐铺满一层;②固体表面上形成纳米聚集体;③固体表面上纳米聚集体与溶液中的纳米聚集体通过边缘堆叠、T形堆叠形成簇状物;④固体表面的聚集体与溶液中的聚集体通过脂肪侧链接触形成絮凝物。

关键词: 沥青质聚集, 沥青质沉积, 多层吸附模型, 络合机制, 粗粒化方法, 平均力势

Abstract:

The complexation mechanism of asphaltenes on the solid surface provides an important theoretical basis for solving the difficulties in exploiting residual oil. To provide a theoretical basis for the development of aggregation inhibitors and surfactants, the attachment and aggregation characteristics of asphaltenes on the surface of highly oriented pyrolytic graphite were systematically studied using molecular dynamics simulations, and the free energy changes of asphaltenes during adsorption were calculated. Based on the quantitative criterion of Yen-Mullins model, in combination with the average interaction molecule numbers and density profiles of asphaltenes, this paper quantitatively analyzes the differences in asphaltene aggregation in the solid-liquid interface system and the solvent system. The analysis of molecular dynamics simulation shows that the solid surface will reduce the degree of asphaltene aggregation and accelerate the staged differentiation during aggregation. Four stages of interface process are involved. (1) Asphaltenes gradually cover the solid surface as a layer. (2) Nano-aggregates are formed on the solid surface. (3) Cluster compounds are formed by nano-aggregates on the solid surface and those in solvent through edge stacking and T-shaped stacking. (4) Flocculent polymers are formed by the aggregates on the solid surface contacted with those in solvent by aliphatic side chains.

Key words: asphaltene aggregation, asphaltene deposition, multilayer adsorption model, complexation mechanism, coarse-grained method, potential of mean force

中图分类号: