Synergistic Inhibition of Wax Crystal Growth by Ethylene-Vinyl Acetate Copolymer and Polyvinylpyrrolidone

Wax deposition in crude oil extraction and transportation endangers petroleum industry safety, raises operational costs, and is an urgent key challenge. Exploring collaborative wax prevention mechanisms is of great significance for innovative wax prevention technologies. In our study, molecular dynamics simulations were applied to clarify the combined effect of ethylene-vinyl acetate copolymer (EVA) and polyvinylpyrrolidone (PVP) or PVP derivatives in the process of wax crystal growth. The simulation results demonstrate that the vinyl acetate (VA) side units enhance the adsorption affinity of pyrrolidone-based polymers around the eutectic surface through polarity effects. On surfaces with low wax-EVA eutectic degrees, pyrrolidone-based polymers adsorbed around VA side chains exert a repulsive effect on solute wax molecules via their polar groups, thereby increasing the induction time of wax crystal growth. On high eutectic surfaces, pyrrolidone-based polymers adsorb onto eutectic surfaces via electrostatic interactions with adjacent VA side chains, forming steric hindrances. Here, hydrophobically modified PVP derivatives (PVP-C and PVP-A) compete for eutectic adsorption sites. This disrupts the orderly growth of wax crystals and either dissipates newly formed wax adsorption layers or prevents their formation entirely. Exploring the potential of collaborative wax prevention facilitates breakthroughs in traditional wax inhibitor performance bottlenecks and enables the development of efficient and eco-friendly composite wax inhibitor systems.