Synergistic Drag Reduction Performance of Wormlike Micelle and Polymer-Based Fe3O4 Nanoparticles Composite Solution in Brine

In this study, the composite solutions of wormlike micelles and polymer-based nanoparticles were investigated to explore their synergistic drag reduction performance. The polymer-based nanoparticles (PAM-AMPS/Fe3O4 NPs) were prepared via emulsion polymerization. The chemical composition and microstructure of the PAM-AMPS/Fe3O4 NPs were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In addition, the shear-induced properties and drag reduction performance of the composite solution in brine were systematically investigated. The results show that the prepared PAM-AMPS/Fe3O4 NPs have a nanocluster structure with sizes ranging from 100 to 500 nm. The grafting content and viscosity average molecular weight of PAM-AMPS on the nanoparticles’ surface are 78.88% and 4.99 × 106 g/mol, respectively. The nanoparticles with high-molecular-weight polymers are suitable for use as a drag reducer. The composite solutions exhibit stronger shear-induced structure (SIS) compared to the pure wormlike micelle solution of cetyltrimethyl ammonium chloride/sodium salicylate (CTAC/NaSal) and the pure polymer-based nanoparticles solution. This is attributed to the formation of reinforced concrete structure by the wormlike micelles and polymer-based nanoparticles. The SIS of the composite solution containing 100 mg/L CTAC/NaSal and 30 mg/L PAM-AMPS/Fe3O4 NPs remains even at 20,000 mg/L NaCl, showing excellent salt resistance. Furthermore, the pure wormlike micellar solution shows low drag reduction and a narrow effective Reynolds number range in the drag reduction experiment at 5000 mg/L NaCl. In contrast, the composite solution achieves a maximum drag reduction of 56.16% and an effective Reynolds number range of 4000–30,000, indicating that the combination of polymer-based nanoparticles and wormlike micelles produces a remarkable synergistic drag reduction effect. This study demonstrates that the composite solution holds great potential as a drag reducer for brine pipeline transport.