CH_(4)在原油体系中溶解规律及影响机理  

Dissolution of CH_(4) in the crude oil system:behaviors and mechanisms

作　　者：李秉繁[1] 刘刚[1] 陈雷[1] LI Bingfan;LIU Gang;CHEN Lei(University of Petroleum(East China),Shandong Provincial Key Laboratory of Oil&Gas Storage and Transportation Safety,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：《化工进展》2021年第8期4205-4222,共18页Chemical Industry and Engineering Progress

基　　金：国家自然科学基金(51774315,51574274)。

摘　　要：为了研究甲烷(CH_(4))在原油体系中的溶解过程,本文采用CH_(4)溶解度测试和分子模拟相结合的方式,系统研究了不同温度、压力条件下CH_(4)在原油体系中的溶解行为。以正庚烷为基础油,蜡、胶质、沥青质含量为影响因素,按照L_(16)(4^(3))正交表构建相应的原油体系,并构建胜利原油和南阳原油两种特定比例的原油体系,共18种原油体系。利用分子动力学方法模拟了CH_(4)分子在不同原油体系中的溶解过程,并利用试验结果验证了模拟的可靠性。结果表明:在泡点压力范围内,随着溶气压力的增加,CH_(4)溶解量逐渐增大,但其溶解位置可能发生变化;当溶气压力较低时,CH_(4)分子较为分散地分布在原油体系中,随着CH_(4)溶解量的增多,部分CH_(4)分子会发生聚集;CH_(4)在原油体系中的溶解为物理溶解过程,且CH_(4)溶解过程中范德华力为主要的力学作用方式;原油体系自由体积分数越大,能够为CH_(4)提供的溶解空间越大;原油大分子对CH_(4)溶解量影响程度依次为:蜡<胶质<沥青质,且原油大分子未改变CH_(4)溶解的力学作用方式,并通过力学模型揭示了相互作用能与原油体系体积变化量的线性关系,促进对CH_(4)在原油体系中溶解的分子级理解。In order to study the dissolution process of methane(CH_(4))in the crude oil system,the dissolution behavior of CH_(4) in crude oil systems at different temperatures and pressures was systematically studied by means of CH_(4) solubility test and molecular simulation.Taking n-heptane as the base oil,wax,colloid,and asphaltene content as influencing factors,the corresponding crude oil system was constructed according to L_(16)(4^(3))orthogonal table.Two specific proportion crude oil systems of Shengli crude oil and Nanyang crude oil were constructed,with a total of 18 crude oil systems.The molecular dynamics method was used to simulate the dissolution of CH_(4) in different crude oil systems.The reliability of the simulation was verified by experimental results.The results show that in the range of bubble point pressure,with the increase of dissolved gas pressure,the amount of CH_(4) dissolved gradually increases,but the position of CH_(4) dissolved may change.When the dissolved gas pressure is low,CH_(4) molecules are more dispersed in the crude oil system,and with the increase of CH_(4) dissolved amount,some CH_(4) molecules will accumulate.The dissolution of CH_(4) in crude oil system is a physical dissolution process,and the Van der Waals force is the main mechanical action in the process of CH_(4) dissolution.The larger the free volume fraction of crude oil system is,the larger the dissolution space can be provided for CH_(4).The influence of crude oil macromolecules on CH_(4) dissolution is wax<colloid<asphaltene and the mechanical action mode of CH_(4) dissolution is not changed by crude oil macromolecules.The linear relationship between the interaction energy and the volume change of crude oil system is revealed by mechanical model,which promotes the understanding on the dissolution of CH_(4) in crude oil system molecular-level.

关 键 词：甲烷 原油 溶解 分子模拟 范德华力 自由体积 

分 类 号：TH382[机械工程—机械制造及自动化]