Performance Evaluation of Nano-Mg(OH) ₂ /EVA Composite Pour Point Depressants on the Flowability of Nanyang Waxy Crude Oil

Nanocomposite pour point depressants (PPDs) represent a significant field of research within polymer PPDs, offering substantial enhancements in performance. This study investigates the impact of incorporating surfactant-modified Nano-Mg(OH)2 into ethylene-vinyl acetate (EVA) PPD on the fluidity of Nanyang waxy crude oil. Rheological experiments revealed that the sole use of modified nanoparticles did not notably enhance flow properties. Findings indicate that the alkyl chain length of the surfactant influences the efficacy of the hybrid PPDs (C18 > C16 > C12), affecting the adsorption of EVA onto nanoparticles. Compared with EVA, the oil samples treated with NaSt-MDH/EVA had the best fluidity, with viscosity reduced by 58.85% and pour point further decreased by 4 °C. Sodium oleate, with its double-bond structure, hinders EVA adsorption, leading to a worse effect than EVA PPD. Through using normal and polarized light wax crystal micrographs, we elucidate the mechanism by which the composite PPD aggregates wax crystals, releasing a greater volume of liquid oil and thereby enhancing Nanyang crude oil’s fluidity. This paper presents the introduction of Nano-Mg(OH)2 into nanocomposite PPDs for the first time, offering a novel approach to the development of new PPDs.