重质油中的分子聚集结构及其对重质油稳定性的影响  

Structure of molecular aggregates and its effect on the stability of heavy oil

作　　者：张胜飞[1,2] 徐俊波[1] 温浩[1] 

机构地区：[1]中国科学院过程工程研究所多相复杂系统国家重点实验室,北京100190 [2]中国科学院研究生院,北京100049

出　　处：《计算机与应用化学》2011年第8期965-971,共7页Computers and Applied Chemistry

基　　金：国家自然科学基金资助项目(20776141);国家自然科学基金创新研究群体科学基金资助项目(20821092)

摘　　要：重质油组分分子的聚集是重质油最显著的特征之一,重质油的高粘特性和相态稳定性均与此聚集行为有紧密的联系。为克服实验研究获得重质油微观聚集结构的困难,本文采用Zhang等人针对重质油体系改进的耗散粒子动力学(DPD)方法,研究重质油的分子聚集结构及其对重质油稳定性的影响。根据重质油组分的结构特征,可将重质油表达为其他轻组分、饱和分、芳香分、胶质和沥青质五种DPD模型分子的混合物。模拟结果表明,本文采取的重质油模拟体系和参数是合理的,很好地反映了重质油中的分子聚集结构。重质油具有胶体多分散体系的特征。其中,芳香度最高的沥青质分子对聚集结构的有序性有显著影响,重质油中的胶质具有胶溶作用,能抑制因沥青质分子聚集导致的相分离和聚沉,芳香分与饱和分和其他轻组分将构成胶体的连续相。本文对重质油稳定性的预测获得了与实验研究一致的结果。对于一定的沥青质与芳香分质量比m_(Asph)/m_(Arom),在沥青质与胶质质量比m_(Asph)/m_(Resin)较小的情况下,重质油都将保持稳定。沥青质与胶质的质量比m_(Asph)/m_(Resin)存在一个极限,当大于这个极限时,重质油将出现聚沉。沥青质与芳香分质量比m_(Asph)/m_(Arom)的降低将使重质油的稳定域出现扩张。The aggregation phenomenon of fraction molecules is one of the most evident features of heavy oil,which influences seriously the viscosity and stability of heavy oil.A dissipative particle dynamics（DPD） method modified by Zhang et al.is applied in this work to study the structure of molecular aggregates in heavy oil and its effect on the stability of heavy oil.The heavy oil is represented as the mixture of the coarse-grained DPD model molecules of asphaltene,resin,aromatic,saturate and light fraction,in accordance with molecular structures of the fractions in heavy oil.The DPD simulations show that the coarse-grained DPD models and DPD parameters used in this work can predict well the structure of molecular aggregates in heavy oil.The heavy oil exhibits as a polydispersed colloid system.The ordered structure of aggregates depends greatly on the molecular structure of asphaltenes.Deflocculation of the resins is observed in the simulations,which can reduce the phase splits and coagulation of heavy oil.The fractions of aromatic,saturate and light fraction in heavy oil perform as the continuous phase in colloid system.The prediction of stability of heavy oil presented in this work is consisted with the Shell＇s SARA cross plot.For the certain value of asphaltene-aromatic mass ratio m_（Asph）/m_（Arom）,the heavy oil will be stable as the asphaltene-resin mass ratio m_（Aspt）/m_（Resin） is low.A critical value of asphaltene-resin mass ratio exists.The coagulation of heavy oil will occur when the higher asphaltene-resin mass ratio is approached. The extension of the stable region of heavy oil will be observed when the asphaltene-aromatic mass ratio m_（Asph）/m_（Arom） reduced.

关 键 词：重质油 多分散体系 聚集结构 稳定性 耗散粒子动力学 

分 类 号：TP319[自动化与计算机技术—计算机软件与理论] TE65[自动化与计算机技术—计算机科学与技术]