基于深层原油物性模拟的分子力场优选及验证  

Screening and verification of molecular force field based on physical property simulation of deep oil

作　　者：张英男 李汝传 于顺昌 郭牧之 燕友果 郭文跃 张军 ZHANG Yingnan;LI Ruchuan;YU Shunchang;GUO Muzhi;YAN Youguo;GUO Wenyue;ZHANG Jun(School of Materials Science and Engineering in China University of Petroleum (East China), Qingdao 266580, China;School of Petroleum Engineering in China University of Petroleum (East China), Qingdao 266580, China)

机构地区：[1]中国石油大学(华东)材料科学与工程学院,山东青岛266580 [2]中国石油大学(华东)石油工程学院,山东青岛266580

出　　处：《中国石油大学学报（自然科学版）》2020年第6期162-169,共8页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金面上项目(51874332);中国石油天然气集团有限公司重大科技项目(ZD2019-183-007);中央高校基本科研业务费专项(19CX05001A)。

摘　　要：利用分子动力学模拟方法优选适用于深层高温高压条件下流体物性模拟的分子力场。基于OPLS、COMPASS、CVFF和PCFF力场模拟计算5种典型深层原油组分在不同温度和压力条件下的密度和黏度,并与AP1700物质物性平台数据进行对比,验证OPLS力场的可靠性。以正辛烷和间二甲苯为例,采用从头算分子动力学模拟与分子动力学模拟相结合的方法研究2种原油分子内碳原子间的成键特征,考察温度条件对成键性质的影响。结果表明OPLS力场可为深层原油的物性模拟提供准确的计算结果,为最适用的分子力场;在当前深层油藏条件下,从头算分子动力学模拟与分子动力学模拟所得的成键特征均没有随温度改变而产生明显变化,原油分子的成键特征对温度条件不敏感;模拟所得成键特征吻合良好,证实OPLS力场在深层条件下模拟原油物性时具备较高的可靠性。Molecular dynamics simulation method was used to screen the molecular force field suitable for the simulation of fluid physical properties under deep high-temperature and high-pressure conditions.Based on OPLS,COMPASS,CVFF and PCFF force field,the density and viscosity of five typical deep oil components at different temperatures and pressures were calculated and compared with the AP1700 material physical platform data.It is found that the OPLS force field can provide accurate calculation results for the physical property simulation of deep oil,and it is preferred as the most suitable molecular force field.Further,taking n-octane and m-xylene as examples,a combination of ab initio molecular dynamics simulation and molecular dynamics simulation was used to study the bonding characteristics between carbon atoms in the two oil molecules,the effect of temperature conditions on bonding properties was investigated,and the reliability of OPLS force field was verified.The simulation results show that under current deep oil reservoir conditions,the molecular bonding characteristics obtained from ab initio molecular dynamics simulations and molecular dynamics simulations do not change significantly with temperature,indicating that the bonding characteristics of crude oil molecules are not sensitive to temperature.The bonding characteristics obtained by the two simulations are in good agreement,confirming that the OPLS force field is reliable in the physical property simulation of deep oil.

关 键 词：深层原油 物性 分子力场 分子动力学模拟 分子成键特征 

分 类 号：TE19[石油与天然气工程—油气勘探]