Study on the effect of modified magnetic nanoparticles Co3O4@HPAM monomer ratio on viscosity reduction of thick oil emulsification

To improve the dispersibility and emulsification performance of magnetic nanoparticles, this study first synthesized three modified magnetic nanoparticles (Co 3 O 4 @HPAM) with different monomer ratios and characterized their physical properties. On this basis, the effects of the modified magnetic nanoparticles with different monomer ratios on the emulsification and viscosity reduction of thick oil were investigated by stability and rheology; finally, the emulsification and viscosity reduction mechanism was revealed by combining the zeta potential, surface tension, contact angle, and oil droplet distribution. The results showed that Co 3 O 4 @HPAM with three different monomer ratios was successfully synthesized and exhibited good dispersibility. With the increase of monomer ratio, the emulsion water fraction decreased first and then increased, and the viscosity reduction decreased first and then increased. At a mass fraction of 0.04%, the sample with a 15% monomer ratio exhibited the lowest water separation rate (6.45% at 4 h) and the highest viscosity reduction rate (97.93%). This phenomenon occurs because, at a 15% monomer ratio, the modified magnetic nanoparticles have a higher negative charge, a larger contact angle, lower oil-water interfacial tension, and smaller, more uniformly distributed oil droplets. This study offers a theoretical foundation for using magnetic nanoparticles in heavy oil emulsification to reduce viscosity.