Experimental study of the effects of a magnetic field/magnetic field-ferromagnetic nanocomposite pour point depressant on wax deposition.

A magnetic field and pour point depressant, as a new avenue for improving the submarine pipeline flow of waxy oils, has attracted increasing attention along with the development of efficient wax mitigation techniques. Although advances have been made recently in understanding the rheological behavior and crystallization properties of waxy oils, the effect of magnetic field and pour point depressants on wax deposition remains an open question. In this work, a ferromagnetic nanocomposite pour point depressant (FNPPD) was prepared. The variations in wax deposition mass and component under the effect of different magnetic treatments and magnetic field-FNPPDs were investigated using cold fingers and high-temperature gas chromatography. It was evident that both the high-intensity and high-frequency magnetic fields generated by the magnet and magnetic coil can effectively reduce the deposition mass and have a long-term magnetic history effect. The synergistic effect of magnetic fields and FNPPDs concurrently reduced the thickness/mass and wax content in the deposition layer, as compared to the individual use of magnetic fields or FNPPDs. The wax precipitation properties and wax crystal morphology of waxy oils under the action of the magnetic field were characterized by differential scanning calorimetry, focused beam reflectance measurement and polarizing microscopy experiments, and the mechanism of the magnetic field was elaborated from the perspective of crystallization kinetics by combining the fitting analysis of Avrami and size-independent growth model.