Dynamic properties of microspheres at the nanoscale and mechanisms for their application in enhanced oil recovery

A carbamate surfactant was synthesized using octadecanol polyoxyethylene ether(AEO) and isocyanatoethyl methacrylate(IEM) as functional monomers. Subsequently, active-carbamate-surfactant-modified PER nanomicrospheres were prepared through two-phase aqueous dispersion polymerization, utilizing acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and ethylene glycol dimethacrylate (EGDMA) as raw materials. The microstructures and properties of the nanomicrospheres were characterized and examined using infrared spectroscopy, nanolaser particle size analysis, thermogravimetric analysis, scanning electron microscopy, rheometry, rotating drop ultra-low interfacial tensiometry, and core-driven experiments. The results revealed that the synthesized PER nanomicrospheres exhibit a uniform particle size distribution, with an average particle size of 336 nm. Furthermore, the nanomicrospheres exhibit a thermal decomposition temperature of 278℃, demonstrating good thermal stability. The nanomicrospheres also exhibit favorable expansion and viscoelastic properties. Upon the injection of 3wt.% of the PER nanomicrospheres into a non-homogeneous core, the blocking rate (η) reaches 90.32%, while the recovery rate increases by 30.2%. This improvement is attributed to the unique structural design of the nanomicrospheres, allowing them to form a thin film at the three-phase oil–water-rock interface and promoting oil emulsification and stripping. Overall, the PER nanomicrospheres effectively control fluid dynamics within reservoirs, mitigate the loss of oil and gas resources, enhance the economic benefits of oil and gas fields, and thus demonstrate good application prospects.