Preparation and Performance Analysis of a Dimension-Controlled Nano-Drag-Reducing Agent for Low-Permeability Reservoirs

Graphene oxide (GO), as a derivative of graphene, is rich in reactive functional groups on its surface for modification, and the modified graphene oxide (M-GO) has excellent special properties. In this paper, the improved Hummer’s method was used to analyze GO by adjusting the amount of oxidant (potassium permanganate), oxidation time, and temperature, using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and laser particle size measurement. The successful synthesis of dimension-controlled GO in the range of 630–1000 nm was confirmed. On this basis, modified graphene oxide (O-M-GO) was prepared by grafting octadecyltrimethoxysilane (OCT). The successful synthesis of O-M-GO was confirmed by FT-IR and XRD. Through a contact angle test, the contact angle of GO before modification was 80 ± 0.5° and that of O-M-GO after modification was 105 ± 0.5°. Combined with SEM analysis, the change in the wettability of O-M-GO was clarified. Core flow test results showed that after O-M-GO was injected into the core, the subsequent brine injection pressure decreased by 14.21%, and the permeability was 1.166 times that before the brine injection. When the injection concentration was 50 mg/L, the drag reduction rate was 14%.