Modified Carbon Quantum Dots Based Nanocomposite System for Enhanced Oil Recovery in Low Permeability Reservoir

As conventional polymers and surfactants approach their limitations in oil recovery, the rapid advancement of nanomaterials offers promising opportunities for chemical enhanced oil recovery (EOR). Among these, carbon quantum dots (CQDs), classified as zero-dimensional nanomaterials, have garnered significant attention from petroleum researchers due to their nanoscale size and environmentally friendly characteristics. In this study, a novel nanocomposite comprising poly(ethylene glycol) (PEG)-functionalized CQDs and purified petroleum sulfonate (PPS) surfactant was synthesized. Experimental results demonstrated that the nanocomposite significantly improved oil recovery during imbibition tests by reducing interfacial tension and enhancing wettability. Moreover, core flooding tests revealed that the oil recovery achieved by the nanocomposite surpassed the combined recovery obtained from PEG-functionalized CQDs and PPS surfactants alone, indicating a synergistic effect between the two components. This synergism was attributed to mechanisms such as disjoining pressure, optimal emulsification, and reduced adsorption, which collectively contribute to effective oil displacement. These findings highlight the potential of the carbon-based nanocomposite system as a promising oil displacement agent for EOR applications.