Enhanced oil recovery (EOR) plays a critical role in optimizing oil extraction from existing fields to satisfy global energy demands while mitigating environmental impact. One promising EOR technique involves injecting water with reduced surface tension utilizing deep eutectic solvents (DESs). Despite early experimental support, the efficacy of aqueous-DES EOR varies and depends on factors such as connate water saturation, water salinity, and reservoir wettability. The recovery mechanisms for aqueous DESs are poorly understood due to the intricate nature of oil components and reservoir formation. In this paper, we investigate the role of DESs in the EOR process through molecular dynamics (MD) simulations. Three different types of DES molecules, such as choline chloride : urea (ChCl : U), choline chloride : ethylene glycol (ChCl : EG), and menthol : salicylic acid (M : SA) are used, for the recovery of dodecane (C₁₂H₂₆) oil from silica and calcite confined surfaces. We have demonstrated the structural characteristics of these systems by examining various physical properties, including interaction energies, density profiles, hydrogen bonds, and interfacial tension (IFT). Different concentrations (10 and 25 wt%) of DESs have been considered to unravel the effect of concentration on oil removal. The wettability of the substrate and the IFT between oil and aqueous DESs are critical physical properties that play a crucial role in influencing EOR phenomena. The IFT between water and oil decreases with the addition of DESs for all DES molecules, leading to a shift in surface behavior from oleophilic to oleophobic and ultimately facilitating the removal of oil from the substrate. Additionally, hydrogen bond formation between DESs and water has been calculated to elucidate its influence on the water/oil interface and substrate wettability. The study provides insights into the fundamental aspects of EOR processes for more effective and sustainable oil extraction.

增强型原油采收（EOR）在优化现有油田的石油开采方面发挥着关键作用，以满足全球能源需求并减轻环境影响。一种有前景的EOR技术涉及使用深共熔溶剂（DESs）降低表面张力的水注入。尽管早期实验提供了支持，但含水DES EOR的效果因油藏饱和度、盐度和亲水性等因素而异。由于石油成分和储层结构的复杂性质，人们对含水DES的回收机制了解有限。本文通过分子动力学（MD）模拟研究了DES在EOR过程中的作用。使用三种不同类型的DES分子，如胆碱氯化物：尿素（ChCl : U）、胆碱氯化物：乙二醇（ChCl : EG）和薄荷醇：水杨酸（M : SA），从二氧化硅和方解石限制表面回收十二烷（C₁₂H₂₆）油。我们通过检查各种物理性质，包括相互作用能、密度分布、氢键和界面张力（IFT），展示了这些系统的结构特征。考虑了不同浓度（10%和25%wt）的DESs以揭示浓度对原油去除的影响。底物的亲水性以及含水DES与油之间的IFT是影响EOR现象的关键物理性质。对于所有DES分子，当加入DES时，水和油之间的IFT降低，导致表面行为从亲油转变为疏油，并最终促进石油从底物上的移除。此外，计算了DESs与水之间形成的氢键以阐明其对水/油界面和底物亲水性的影响。该研究为更有效地进行EOR过程提供了关于基础方面的见解。