国丽萍, 徐枭, 孙海英, 蒋玉卓. 含蜡原油胶凝过程分子动力学模拟[J]. 油气储运, 2022, 41(7): 819-825. DOI: 10.6047/j.issn.1000-8241.2022.07.009
引用本文: 国丽萍, 徐枭, 孙海英, 蒋玉卓. 含蜡原油胶凝过程分子动力学模拟[J]. 油气储运, 2022, 41(7): 819-825. DOI: 10.6047/j.issn.1000-8241.2022.07.009
GUO Liping, XU Xiao, SUN Haiying, JIANG Yuzhuo. Molecular dynamics simulation ongelation process of waxy crude oil[J]. Oil & Gas Storage and Transportation, 2022, 41(7): 819-825. DOI: 10.6047/j.issn.1000-8241.2022.07.009
Citation: GUO Liping, XU Xiao, SUN Haiying, JIANG Yuzhuo. Molecular dynamics simulation ongelation process of waxy crude oil[J]. Oil & Gas Storage and Transportation, 2022, 41(7): 819-825. DOI: 10.6047/j.issn.1000-8241.2022.07.009

含蜡原油胶凝过程分子动力学模拟

Molecular dynamics simulation ongelation process of waxy crude oil

  • 摘要: 胶凝是含蜡原油复杂宏观流变特性的根源,而其流变特性又是管道输送的重要基础数据。根据宏观实验数据建立了两种含蜡原油体系模型,使用Materials Studio软件进行分子动力学模拟,从分子动力学层面研究了含蜡原油胶凝过程的微观机理。结果表明:根据密度、扩散系数判断原油凝点,得到的模拟凝点值与实验值一致;原油降温胶凝时,由于空间网络结构的形成,致使蜡晶分子扩散系数突变、均方位移偏差显著减小;使用径向分布函数表征原油胶凝过程中的微观结构变化发现,在胶凝过程中同种分子间径向分布函数峰值逐渐增大,在凝点温度时蜡晶分子间聚集的程度最大,故蜡晶分子是影响含蜡原油凝点温度的主要原因。研究成果可为含蜡原油管道输送技术基础数据的获取提供理论参考。

     

    Abstract: Gelation of waxy crude oil is the source of its complex macroscopic rheological properties, while the rheological properties of waxy crude oil are the important basic data for pipeline transportation.Herein, two models of waxy crude oil system were established based on the macroscopic experimental data, and the molecular dynamics simulation was carried out using the Materials Studio software. In this way, the microscopic mechanism for gelation process of waxy crude oil was studied from the prospective of molecular dynamics. According to the results, the simulated condensation point value of crude oil is consistent with the experimental value through the judgment based on the density and diffusion coefficient. The sudden change of diffusion coefficient of wax crystal molecules and the deviation of mean square displacement are significantly reduced due to the formation of spatial network structure during crude oil gelation. By characterizing the change of microstructure of crude oil during gelationwith the radial distribution function, it is found that the peak value of radial distribution function between the same types of molecular increases gradually, and the largest degree of aggregation between wax crystals occurs at the condensation point. So, wax crystal molecule is the main factor that affects the condensation point of waxy crude oil. Generally, the research resultscouldprovide a basic theory for the acquisition of basic data concerning the pipeline transportation technology of waxy crude oil.

     

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