A nanocomposite pour point depressant (NPPD), as a new type of wax additive or flow improver for waxy oil, has raised wide attention. Recent advances have been made in the modification of the crystal morphology and the rheological behavior of waxy oil by NPPD. In this work, the effect of NPPD on wax deposition behavior has been studied via a cold finger apparatus. It was found that the deposition mass is obviously eliminated with the addition of NPPD, while the composition analysis by hightemperature gas chromatography (HTGC) indicates that the wax content in the deposit increases. Further, the measured variation of the initial gel time and mass, the critical carbon number, and the carbon number distribution of the deposit is found and should be owed to the effect of NPPD.
Crystallization modification
has been applied in many fields, such
as materials science, petroleum engineering, and chemical engineering.
The modification of organic–inorganic hybrids via paraffin
hydrocarbon crystallization has been significantly important for the
exploration of undersea oil and gas resources. In this work, a metal
oxide organic–inorganic hybrid pour point depressant (MOIH-PPD)
is provided along with an analysis of the microscopic structure of
the paraffin hydrocarbon crystal employing small-angle X-ray scattering
and X-ray diffraction. The MOIH-PPD modified crystal grain exhibited
a decrease in the long period and in the radius of gyration of the
crystal grain and an increase in the thickness of the interface layer
compared with those of the unmodified paraffin crystal. In addition,
the synergistic effect of heterogeneous nucleation and the magnetic
response of MOIH-PPD on the paraffin hydrocarbon system was also investigated,
revealing that the synergism modification yields stress superior to
that of MOIH-PPD or magnetic field alone, which provides insight into
the possibility of the modification of paraffin hydrocarbon crystallization.
Yield stress, as the key parameter to characterize the network strength of waxy oil, is important to the petroleum pipeline safety. Reducing the yield stress of waxy oil is of great significance for flow assurance. In this study, the effect of alternating magnetic field (intensity, frequency) on the yield stress of a waxy model oil with nanocomposite pour point depressant (NPPD) is systematically investigated. An optimum magnetic field intensity and frequency is found for the reduction in yield stress. When adding with NPPD, the heterogeneous nucleation of NPPD contributes to the reduction in yield stress for waxy model oil. Interestingly, the magnetic field is helpful for the modification of yield stress at a lower frequency and intensity before the optimal value; however, the modification is found to be weakened when the magnetic field is further increased after the optimal value. Possible explanation is proposed that the aggregation morphology of wax crystal would be altered and results in the release of wrapped oil phase from the network structure under the magnetic field.
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