Influence of the nano-hybrid pour point depressant on flow properties of waxy crude oil

• Nano-hybrid pour point depressant (NPPD) was prepared and firstly used for waxy crude oil.
• The yield stress and viscosity of waxy crude oil were reduced by 99.3% and 82.1% by NPPD, respectively.
• The high energy barrier inhibited wax crystal aggregation and the formation of gel networks in NPPD doped oil.

The influence of the nano-hybrid pour point depressant (NPPD) on flow properties of waxy crude oil was studied. Rheological results showed that NPPD demonstrated better improvement in viscosity, yield stress and pour point reduction for crude oil than the conventional polymer PPD (N6) did. Moreover, the viscoelastic behavior data showed that the NPPD doped oil had a weaker gel network structure at a low temperature compared with N6 doped oil. Differential scanning calorimetry results revealed that NPPD reduced the wax appearance temperature (WAT) and the wax precipitation amount within the temperature range from WAT to −20 °C. The difference of shape and size of wax crystals in undoped and doped oils was studied by X-ray diffraction and polarized optical microscopy. The total interaction energy between wax particles was calculated according to the Derjaguin–Landau–Verwey–Overbeek theory using ζ potential. It was found that the energy barrier between the wax particles in the NPPD doped oil was higher than that in N6 doped oil. The larger electrostatic repulsion inhibited the aggregation of the wax particles and stabilized the NPPD doped oil system.