基于分子动力学模拟的CH_(4)溶解对原油分子间作用的影响机制研究  

Study on the influence mechanism of CH_(4) dissolution on the intermolecular interaction between crude oil molecules based on molecular dynamics simulation

作　　者：李秉繁[1] 刘刚[1] 陈雷[1] LI Bingfan;LIU Gang;CHEN Lei(Shandong Provincial Key Laboratory of Oil&Gas Storage and Transportation Safety,China University of Petroleum,Qingdao 266580,Shandong,China)

机构地区：[1]中国石油大学(华东)山东省油气储运安全省级重点实验室,山东青岛266580

出　　处：《化工学报》2021年第3期1253-1263,共11页CIESC Journal

基　　金：国家自然科学基金项目(51774315,51574274)。

摘　　要：为了研究甲烷(CH4)溶解对原油分子间作用的影响机制,利用分子模拟方法,分别构建正庚烷与正庚烷、蜡分子、胶质、沥青质的最低能量构型,分析CH4氛围对原油分子间相互作用的影响。以CH4/原油分子体系模型为研究对象进行分子动力学模拟,考察CH4溶解对原油分子体系黏度的影响,根据原油分子间相互作用、径向分布函数、体积应变、自扩散系数以及体系内聚能密度变化规律揭示CH4溶解对原油分子间作用的影响机制,发现CH4的溶解增大了原油分子间的间距,削弱了体系内原油分子间的范德华作用;体积膨胀为原油分子的热运动提供了更多的空间,原油分子热运动加剧,使得油品的流动能力增强;不同原油分子体系的黏度、径向分布函数、体积应变、自扩散系数以及内聚能密度的变化趋势类似,原油分子体系中蜡、胶质、沥青质的存在并未改变CH4对原油分子间作用的影响机制。To study the influence mechanism of methane dissolution on the intermolecular interaction between crude oil molecules.The lowest energy configurations of n-heptane and n-heptane,wax,colloid,asphaltene were constructed by molecular dynamics method,and the effect of CH4 atmosphere on the interaction between crude oil molecules was analyzed.Based on the molecular dynamics simulation of CH4/crude oil molecular system model,the effect of CH4 dissolution on the viscosity of crude oil molecular system was investigated.Five parameters,including intermolecular interaction,radial distribution function,volume strain,self diffusion coefficient,and cohesive energy density,were used to reveal the influence mechanism of intermolecular interaction of crude oil by CH4 dissolution.The results showed that the dissolved CH4 in crude oil molecular system increased the distance between the crude oil molecules,weakened the van der Waals effects between crude oil molecules.Under this condition,volume expansion provided more space for the thermal movement of crude oil molecules,intensified the thermal movement of crude oil molecules and then enhanced the flow capacity of crude oil.Moreover,there were􀤃similar rules of the effect of dissolved CH4 on viscosity,radial distribution function,volume strain,self-diffusion coefficient and cohesion energy density in different crude oil molecular system.However,the existence of wax,colloid and asphaltene in crude oil molecular system does not change the influence mechanism of CH4 on the intermolecular interaction of crude oil.

关 键 词：甲烷 原油 分子模拟 溶解 分子间作用 影响机制 

分 类 号：TE832[石油与天然气工程—油气储运工程]