Abstract
Polymer hydrogels are the optimal hydrogels for water channeling control applications, and water-dominant channels in deep reservoirs are often blocked by them.A dual-network hydrogel system (DN-Gel) is innovatively proposed in this study. A chemical crosslinking network (ACL-HG) is constructed via glycidyl methacrylate (GMA), poly(ethylene glycol) methyl ether methacrylate (PEGMA), and dopamine methacrylamide (DMA), and is composited with a physical crosslinking network (GQDs-Gel) of functionalized graphene quantum dots (GQDs-GX)/ascorbic acid. A dense dual-network structure is formed through the synergistic effect of Michael addition reaction and hydrogen bonding.FTIR and SEM characterization results show that DN-Gel possesses both the functional group characteristics of the chemical crosslinking network and the nano-reinforcement effect of the physical crosslinking network, and its cross-sectional pore structure is significantly denser than that of single-network hydrogels.Under the optimal ratio and concentration, the viscosity reduction rates of DN-Gel both before and after three shearing cycles within 56 days are maintained below 20%.Under high-temperature and high-salinity conditions, a mass retention rate of over 80.6% is achieved after 60 days.Core simulation results show that DN-Gel has a breakthrough pressure gradient of 129.21 MPa/m and a permeability change rate as high as 99.21%, which is significantly improved compared with traditional plugging agents.This study provides a new material design method and theoretical basis for the green and efficient plugging of sandstone reservoirs.