Probing the interaction between asphaltene-wax and its effects on the crystallization behavior of waxes in heavy oil via molecular dynamics simulation  

作　　者：Yong Hu Xi Lu Hai-Bo Wang Ji-Chao Fang Yi-Ning Wu JianFang Sun 

机构地区：[1]SINOPEC Petroleum Exploration and Production Research Institute,Beijing,102206,China [2]Shandong Key Laboratory of Oilfield Chemistry,School of Petroleum Engineering,China University of Petroleum(East China),Qingdao,266580,Shandong,China

出　　处：《Petroleum Science》2024年第4期2839-2848,共10页石油科学（英文版）

基　　金：financially supported by the Project funded by China Postdoctoral Science Foundation (NO.2022M723500);the National Natural Science Foundation of China (NO.52204069);the Sinopec Science and Technology Project of China (NO.P22015)。

摘　　要：High content of asphaltenes and waxes leads to the high pour point and the poor flowability of heavy oil,which is adverse to its efficient development and its transportation in pipe.Understanding the interaction mechanism between asphaltene-wax is crucial to solve these problems,but it is still unclear.In this paper,molecular dynamics simulation was used to investigate the interaction between asphaltenewax and its effects on the crystallization behavior of waxes in heavy oil.Results show that molecules in pure wax are arranged in a paralleled geometry.But wax molecules in heavy oil,which are close to the surface of asphaltene aggregates,are bent and arranged irregularly.When the mass fraction of asphaltenes in asphaltene-wax system(ω_(asp))is 0-25 wt%,the attraction among wax molecules decreases and the bend degree of wax molecules increases with the increase ofω_(asp).Theω_(asp)increases from 0 to 25 wt%,and the attraction between asphaltene-wax is stronger than that among waxes.This causes that the wax precipitation point changes from 353 to 333 K.While theω_(asp)increases to 50 wt%,wax molecules are more dispersed owing to the steric hindrance of asphaltene aggregates,and the interaction among wax molecules transforms from attraction to repulsion.It causes that the ordered crystal structure of waxes can't be formed at normal temperature.Simultaneously,the asphaltene,with the higher molecular weight or the more hetero atoms,has more obvious inhibition to the formation of wax crystals.Besides,resins also have an obvious inhibition on the wax crystal due to the formation of asphalteneresin aggregates with a larger radius.Our results reveal the interaction mechanism between asphaltene-wax,and provide useful guidelines for the development of heavy oil.

关 键 词：Heavy oil Interaction mechanism ASPHALTENES Waxes Molecular dynamics 

分 类 号：TE621[石油与天然气工程—油气加工工程]