Electrical Treatment of Waxy Crude Oil To Improve Its Cold Flowability

Ma, Chenbo; Lu, Yingda; Chen, Chaohui; Feng, Kai; Li, Zixin; Wang, Xinyi; Zhang, Jinjun

doi:10.1021/acs.iecr.7b02140

Cited by 50 publications

(21 citation statements)

References 35 publications

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“…When the oil temperature drops below the wax appearance temperature (WAT), wax will start to precipitate out as wax crystals. This wax precipitation can manifest to a variety of flow assurance issues for the transportation of waxy crude oils, including increased oil viscosity, wax deposition, , and oil gelation during temporary operation shutdown …”

Section: Introductionmentioning

confidence: 99%

Influence of Asphaltene Polarity on Crystallization and Gelation of Waxy Oils

Han

et al. 2018

Energy Fuels

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We report for the first time the results from a systematic investigation of how asphaltenes of different polarity affect crystallization and gelation of waxy oils. The more polar asphaltenes were found to be more aromatic in nature and more highly self-aggregated in the solvent. The presence of less polar asphaltenes in the waxy oil reduced the wax appearance temperature and wax precipitation to a greater degree compared to more polar asphaltenes, which was mainly attributed to the difference in the aggregation state of asphaltenes of different polarity. Reducing the polarity of asphaltenes present in the oil also resulted in a lower gelation temperature, lower storage modulus, and lower yield stress, which was probably because the less polar asphaltenes were more similar to wax on the molecular level and, thus, more readily interacting with wax. Notably, a 99% reduction in the yield stress was observed upon the addition of the least polar asphaltenes examined in the present work, in contrast to the 62% yield stress reduction upon the addition of the most polar asphaltenes. This observation may be of industrial significance because it suggests that the crude oil containing less polar asphaltenes may form a softer gel or deposit that is more easily broken or removed. Microscopic analysis showed that the wax crystals precipitated in the presence of less polar asphaltenes have a smaller aspect ratio.

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Section: Introductionmentioning

confidence: 99%

Influence of Asphaltene Polarity on Crystallization and Gelation of Waxy Oils

Han

et al. 2018

Energy Fuels

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“…A Nikon OPTIPHOT2-POL polarized microscope equipped with a thermal stage manufactured by Linkam Scientific Instruments, Ltd. was used to inspect wax crystals. Procedures to prepare a specimen for microscopy observation can be found in previous studies. , The size of the wax crystals was analyzed by ImageJ software …”

Section: Methodsmentioning

confidence: 99%

Effect of Pour Point Depressants on the Impedance Spectroscopy of Waxy Crude Oil

Chen

Huang

et al. 2020

Energy Fuels

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Treatment with pour point depressant (PPD) can significantly improve the cold flowability of waxy crude oil, enabling the safe and efficient transportation of waxy crude oils through pipelines. It has been observed that the electrical properties of waxy oil, such as the dielectric constant, ζ-potential, etc., change upon PPD treatment. In a previous study, we reported that wax precipitation results in a significant change of impedance spectroscopy (IS) of a waxy oil, i.e., a second semicircle appears in the Nyquist diagram and becomes increasingly bigger with increasing amount of precipitated wax. In this study, we found that the addition of PPD may significantly reduce the second semicircle, and the more effective the PPD is, the more reduced the second semicircle will be. Equivalent circuit models suggest that the impedance characteristics of the liquid phase of wax-in-oil suspension change little with PPD addition, but the capacitance of wax particles increases and the resistance of wax particles decreases significantly. A positive correlation between the viscosity reduction and the reduction of resistance of wax particles caused by PPD is discovered. After PPD treatment, the polar functional groups in PPD molecules potentially induce charge on wax particles as they precipitate, causing the relationship between the viscosity and conductivity to approach the fractional Walden rule. This work explains the reason for the improvement of flowability upon PPD addition from a perspective of IS, which provides some new proofs to understanding the functional mechanism of PPD.

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“…14e), co-crystallization in EVA or heterogeneous nucleation in NPPD-doped system (He et al 2016;Norrman et al 2016) demonstrates the modification of crystal morphology; consequently, the yield stress is reduced to 46 Pa (EVA) and 30 Pa (NPPD) at 15 °C. It is interesting that an aggregation trend of wax crystals is observed after treated with magnetic field, which contributes to the release of liquid oil wrapped between crystal network (Ma et al 2017;Tao et al 2014). The change of wax crystal morphology under magnetic field results in a lower yield stress (undoped oil, 196 Pa to 127 Pa; EVA-doped oil, 46 Pa to 8 Pa; NPPD-doped oil, 30 Pa to 5 Pa) (AlSabagh et al 2016).…”

Section: The Effect Of Magnetic Frequency On Synergistic Modificationmentioning

confidence: 99%

“…Physical methods, as electrical or magnetic, are widely investigated (Bacri et al 1995;Du et al 2018;Martínez-Palou et al 2011;Ma et al 2017;Tao et al 2014). Both the electrical and magnetic treatments can depress the viscosity of waxy crude oil (Martínez-Palou et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Synergistic effect of magnetic field and nanocomposite pour point depressant on the yield stress of waxy model oil

et al. 2020

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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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Electrical Treatment of Waxy Crude Oil To Improve Its Cold Flowability

Cited by 50 publications

References 35 publications

Influence of Asphaltene Polarity on Crystallization and Gelation of Waxy Oils

Influence of Asphaltene Polarity on Crystallization and Gelation of Waxy Oils

Effect of Pour Point Depressants on the Impedance Spectroscopy of Waxy Crude Oil

Synergistic effect of magnetic field and nanocomposite pour point depressant on the yield stress of waxy model oil

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