Influence of EVA/nano-sepiolite on the wax crystal and rheological property of Daqing crude oil

In this paper, the organic nano-sepiolite was modified to obtain highly dispersibility in the oil phase, and then, EVA (ethylene-vinyl acetate)/nano-sepiolite was prepared by melt blending. The effects of un-doped/doped different NPPDs oil samples on the pour point, gel point, viscosity, and yield value of Daqing crude oil were evaluated. The changes of wax crystal morphology at low temperature were observed by polarizing optical microscopy (POM). The results show that due to the heterogeneous nucleation mechanism and high dispersion in the oil phase, EVA/nano-sepiolite has a better effect on reducing pour point and makes EVA have a higher local concentration in the oil phase, which weakens the wax crystal structure, and greatly improved the low temperature rheology of Daqing crude oil. Compared with pure EVA, EVA/nano-sepiolite can further reduce the pour point, gel point, viscosity, and yield value of Daqing crude oil at the optimum additive concentration of 200 ppm. Among them, it can further reduce the pour point 2 °C and further reduce the gel point 0.93 °C; at 15 °C, the viscosity reduction rate was 20% and the yield value at 15 °C was reduced by 82%.