Molecular dynamics simulation of microemulsion phase behavior

doi:10.3969/j.issn.1006-6535.2026.02.010

Abstract

Abstract: In response to the insufficient understanding of phase behavior regulation-control mechanisms of microemulsions in oil displacement processes,a molecular structure model of an C₈H₁₈-SDBS/C₄H₁₀O-NaCl solution was constructed using Materials Studio based on molecular dynamics principles.Systematic simulations were conducted to investigate the wetting mechanism and interfacial behavior of microemulsions.Through molecular dynamics,iso-butanol(C₄H₁₀O)and sodium dodecylbenzenesulfonate (SDBS) ratios were screened to find the optimal compatibility and lowest total energy of the system.The adsorption configuration,spatial distribution,interaction energy,and radial distribution function were then analyzed.The results show that the minimum binding energy of the system C₈H₁₈-SDBS/C₄H₁₀O-NaCl is -68.21 kcal/mol,corresponding to a composition of 8.0%C₄H₁₀O+0.5%NaCl+4.0%SDBS,at which the system is the most stable;NaCl has an insignificant effect on system stability.In terms of wetting behavior,changes in iso-butanol(C₄H₁₀O)concentration induce phase transitions.At 6.0%~7.5% iso-butanol(C₄H₁₀O),oxygen atoms primarily interact with the hydrophilic head of SDBS,rendering the system water-wet;at 8.0%,oxygen interacts equally with hydrophilic and hydrophobic groups,making the system neutral;at 8.5%,oxygen preferentially associates with hydrophobic groups,rendering the system oil-wet.The microemulsion formed with 8.0% iso-butanol(C₄H₁₀O)yields the best results in reducing interfacial tension and modulating wettability:it can improve microscopic oil displacement efficiency,expand macroscopic sweep volume,increase the recovery efficiency by 31.3 percentage points,and reduce water cut by 20.2 percentage points.This study provides important guidance for optimizing microemulsion formulations for oil displacement and enhancing oil recovery.

Key words: molecular dynamics, radial distribution function, SDBS, microemulsion, enhanced oil recovery

CLC Number:

TE357

ZHOU Zhijun, ZHANG Qi, YI Xi, LI Juntao, WANG Shuyang, WANG Chenzhu. Molecular dynamics simulation of microemulsion phase behavior[J]. Special Oil & Gas Reservoirs, 2026, 33(2): 89-99.

References

[1] 周朝辉,张晓杰,张群,等.基于超浸润现象的高效提高原油采收率方法[J].石油勘探与开发,2025,52(5):1154-1165.
ZHOU Zhaohui,ZHANG Xiaojie,ZHANG Qun,et al.New high-efficiency system for improving oil recovery based on the superwetting phenomenon[J].Petroleum Exploration and Development,2025,52(5):1154-1165.
[2] TARTAROG,MATEOS H,SCHIRONE D,et al.Microemulsion microstructure(s):a tutorial review[J].Nanomaterials,2020,10(9):1657.
[3] 景俊浩,秦冰,江建林,等.微乳液在三次采油中的研究现状与进展[J].石油炼制与化工,2025,56(8):171-178.
JING Junhao,QIN Bing,JIANG Jianlin,et al.Microemulsion and its application in tertiary oil recovery[J].Petroleum Processing and Petrochemicals,2025,56(8):171-178.
[4] WINSOR P A.Hydrotropy,solubilisation and related emulsification processes[J].Transactions of the Faraday Society,1948,44:376-398.
[5] 阙庭丽,吴丛文,云庆庆,等.环烷基石油磺酸盐复配体系微乳液性能评价[J].油气田地面工程,2023,42(8):12-17.
QUE Tingli,WU Congwen,YUN Qingqing,et al.Evaluation of microemulsion properties of naphthenic petroleum sulfonate composite system[J].Oil-Gas Field Surface Engineering,2023,42(8):12-17.
[6] 关丹,唐文洁,阙庭丽,等.石油磺酸盐驱油体系中相微乳液提高采收率[J].石油化工,2025,54(2):233-239.
GUAN Dan,TANG Wenjie,QUE Tingli,et al.Recovery enhancement by medium-phase microemulsion in petroleum sulfonate oil displacement system[J].Petrochemical Technology,2025,54(2):233-239.
[7] BUI K,AKKUTLU I Y,ZELENEV A S,et al.Insights into mobilization of shale oil by use of microemulsion[J].SPE Journal,2016,21(2):613-620.
[8] JANG S S,LIN S T,MAITI P K,et al.Molecular dynamics study of a surfactant-mediated decane-water interface:effect of molecular architecture of alkyl benzene sulfonate[J].The Journal of Physical Chemistry B,ACS Publications,2004,108(32):12130-12140.
[9] 李坤,顾伯勤,王成.基于分子动力学的密封材料界面结合能研究[J].合成橡胶工业,2021,44(4):289-293.
LI Kun,GU Boqin,WANG Cheng.Study on interface binding energy of sealing materials based on molecular dynamics[J].China Synthetic Rubber Industry,2021,44(4):289-293.
[10] 高煦轲,常曦文,仝殿杰,等.基于分子动力学的聚丙烯电热应力老化特性分析[J].电力电容器与无功补偿,2024,45(1):88-94.
GAO Xuke,CHANG Xiwen,TONG Dianjie,et al.Analysis of electrothermal stress aging characteristics of polypropylene based on molecular dynamics[J].Power Capacitor & Reactive Power Compensation,2024,45(1):88-94.
[11] 陈炫来,严国超,阳湘琳,等.SDS/SDBS对无烟煤润湿性影响的分子动力学模拟[J].煤炭科学技术,2022,50(12):185-193.
CHEN Xuanlai,YAN Guochao,YANG Xianglin,et al.Molecular dynamics simulation of the effect of SDS/SDBSon the wettability of anthracite[J].Coal Science and Technology,2022,50(12):185-193.
[12] 李高占,焦提留,霍月青,等.几种磺酸盐类阴离子表面活性剂的性能[J].印染助剂,2021,38(11):45-48.
LI Gaozhan,JIAO Tiliu,HUO Yueqing,et al.Properties of several sulfonate anionic surfactants[J].Textile Auxiliaries,2021,38(11):45-48.
[13] 黄鑫淼,林伟,韩登林,等.致密油藏CO₂驱和水驱分子动力学模拟及微观机理[J].西安石油大学学报(自然科学版),2024,39(3):72-81.
HUANG Xinmiao,LIN Wei,HAN Denglin,et al.Study of microscopic mechanism of CO₂/water flooding in tight oil reservoir based on molecular dynamics simulation[J].Journal of Xi′an Shiyou University(Natural Science Edition),2024,39(3):72-81.
[14] KUNDU K,PUAL B K.Interfacial composition,thermodynamic properties and structural parameters of water-in-oil microemulsions stabilized by 1-pentanol and mixed anionic+polyoxyethylene type nonionic surfactants[J].Colloid and Polymer Science,2013,291(3):613-632.
[15] 周志军,张祺,衣犀,等.宋芳屯外围油田“二三结合”综合措施调整[J].油田化学,2025,42(3):509-519.
ZHOU Zhijun,ZHANG Qi,YI Xi,et al.Integrated“secondary-tertiary combination”adjustment strategy for peripheral development in Songfangtun Oilfield[J].Oilfield Chemistry,2025,42(3):509-519.
[16] 朱哲涵,何芬,杨振航,等.微乳液化学驱油提高采收率微观可视化[J].新疆石油天然气,2024,20(2):79-86.
ZHU Zhehan,HE Fen,YANG Zhenhang,et al.Micro-scale visualization of enhanced oil recovery by micro-emulsion chemical flooding[J].Xinjiang Oil & Gas,2024,20(2):79-86.
[17] 孟筠青,王丽娟,王顾儒,等.表面活性剂对硅尘润湿性影响的分子模拟[J].安全与环境学报,2023,23(7):2360-2365.
MENG Junqing,WANG Lijuan,WANG Guru,et al.Molecular simulation of the influence of surfactants on the wettability of silica dust[J].Journal of Safety and Environment,2023,23(7):2360-2365.
[18] LIU Y,LI H,GAO M,et al.Experimental and molecular dynamics study into the surfactant effect upon coal wettability[J].RSC Advances,Royal Society of Chemistry,2021,11(40):24543-24555.
[19] 宋洁,樊文娜,牛育华,等.醇对W/O型石油醚微乳液性能的影响[J].精细化工,2016,33(11):1212-1218.
SONG Jie,FAN Wenna,NIU Yuhua,et al.Effects of alkanol on properties of W/O petroleum ether microemulsion[J].Fine Chemicals,2016,33(11):1212-1218.
[20] DU X,LU Y,LI L.Structures and interfacial properties of alkylbenzenesulfonate ge mini surfactants[J].Fine Chemicals,2007,24(4):328.
[21] 张彩霞,李世勇,张文超,等.SVT20旋转滴界面张力仪测量原理及影响因素分析[J].石油钻探技术,2011,39(1):115-118.
ZHANG Caixia,LI Shiyong,ZHANG Wenchao,et al.The field application of SVT20 spinning drop video tensiometer to improve oil recovery[J].Petroleum Drilling Techniques,2011,39(1):115-118.