# Progress on the Application of Nanomaterial Expansion in Oil Displacement
## 5 Conclusions  
This paper systematically reviews the progress in the application of nanomaterials in oil displacement, with a focus on mechanisms for enhanced oil recovery, nano-swelling oil displacement mechanisms, and technical challenges. Through in-depth analysis of interfacial regulation, wettability alteration, and crude oil rheology optimization mechanisms, it provides theoretical support for the engineering application of nano-displacement technology. The key conclusions are as follows:  
1. Synergistic Multi-Mechanism Effects of Nanomaterials for Enhanced Oil Recovery  
Nanomaterials synergistically enhance oil recovery through three core mechanisms: significantly reducing oil-water interfacial tension, regulating rock wettability, and decreasing crude oil viscosity. Experiments demonstrate that active silica nanofluids can reduce interfacial tension by up to 73.8%. Optimal wettability regulation occurs under neutral-wet conditions, achieving a maximum recovery enhancement of 52.6%. Acidic silica nanoparticles reduce heavy oil viscosity by 30%. Nanoparticles form interfacial nanolayers that replace pure interfaces, and their combination with surfactants further enhances emulsification and oil stripping efficiency.  
2. Unique Mechanisms and Performance Advantages of Nano-Swelling Displacement  
Hydrophilic silica nanomaterials induce drastic expansion of crude oil droplets through interfacial adsorption, with volume expansion of nearly a thousand-fold. Their structural disjoining pressure forms wedge-shaped films at oil-water-solid three-phase regions, driving contact line contraction. The inner contact line contraction rate reaches 0.6617 \(\times\) 10\({}^{-5}\) cm/s, significantly improving oil stripping efficiency, with modified nanosheet fluids achieving up to 95.7% displacement efficiency. Amphiphilic Janus nano-materials reduce interfacial tension to 0.01-0.1 mN/m and enhance recovery by 21.5% at ultralow concentrations (0.005 wt%).  
3. Technical Challenges and Future Development Directions  
Current technology faces challenges, including insufficient stability in extreme reservoir environments, unclear mass transfer mechanisms in porous media, and the high costs of eco-friendly materials. Future efforts should focus on developing functionalized Janus materials and core-shell composites resistant to high-temperature/high-salinity environments, optimizing displacement parameters using artificial intelligence, advancing bio-based biodegradable nanomaterials, and implementing composite technologies combining supercritical CO\({}_{2}\) with nanoemulsions.  
The core contribution of this work lies in revealing how nanomaterials enhance oil recovery through synergistic mechanisms of interfacial tension reduction, directional wettability control, and structural disjoining pressure. It innovatively proposes theoretical models of droplet dynamic expansion and wedge-film diffusion in nano-swelling displacement. The key findings include the following: neutral-wet conditions maximize recovery enhancement; Janus nanomaterials achieve orders-of-magnitude interfacial tension reduction at ultralow concentrations; structural disjoining pressure is the core physical mechanism for microscopic oil stripping. Material innovation and intelligent modeling will drive future advancements toward efficient and environmentally sustainable technologies.  
[PERSON] contributed to the conceptualization and funding acquisition, [PERSON] contributed to data curation and formal analysis, and [PERSON] contributed to validation and visualization. [PERSON] is responsible for inspection and proofreading. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China (Grant No. 52474060)--Microscopic scale shale oil start-up mechanical mechanism.  
The authors declare no competing interests.