Unlocking the Mechanism of Unique Interfacial Behavior and Highly Efficient Oil Displacement of Amphiphilic Carbon Nanosheets

Energized nanomaterials have great potential in enhancing oil recovery due to their excellent interfacial effects, but the microscopic oil displacement mechanism has not been fully studied. In order to further study the oil displacement efficiency of nanomaterials, a two-dimensional graphene oxide amphiphilic carbon nanosheet (ACN) was prepared from graphene oxide and alkyl glycidyl ether. The interfacial activity and oil displacement efficiency of the ACN were evaluated by experimental characterization, core physical simulation, and microscopic visualization experiments. The experimental results show that the lateral dimensions of the ACN span from several hundred nanometers to several micrometers, with the thicknesses of only 2 nm. The ACN can spontaneously accumulate at the oil–water interface, thereby reducing the interfacial tension and enhancing the stability of the oil–water interfacial film, demonstrating superior interfacial activity. Furthermore, the ACN adheres to the rock surface, turning oil-wet into water-wet and water-wet into strongly water-wet, thereby facilitating the detachment of oil droplets. In the displacement experiments, the ACN can stabilize the displacement front, diminish the viscous resistance between oil droplets and pore walls, and enhance the recovery rates of both residual and remaining oils. The application of ACN nanofluids at a concentration of 100 mg/L enhances crude oil recovery by 16.7% compared to traditional single-brine flooding. It is anticipated that this high-performance material will find broad applications in chemically enhanced oil recovery.