An investigation to the mechanism of the electrorheological behaviors of waxy oils

Chen, Chaohui; Zhang, Jinjun; Xie, Yiwei; Huang, Qian; Ding, Yifei; Zhuang, Yu; Xu, Miaomiao; Han, Shanpeng; Li, Zixin; Li, Hongying

doi:10.1016/j.ces.2021.116646

Cited by 21 publications

(7 citation statements)

References 34 publications

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“…The flow restart of waxy crude gelled pipeline has remained the major challenge for several decades, and a comprehensive understanding of gelation and degelation behaviors is sought. − Several techniques have been considered for performing flow assurance of a gelled pipeline. − These may be categorized into thermal, chemical, and mechanical treatment techniques, utilizing active or passive methods. − Pour point depressants are used as a chemical method to inhibit wax crystal agglomeration and gelation. Generally, polymers, comb-polymers, polymer nanocomposites, nanoparticles, and nanohybrids are utilized as pour point depressants, lowering the crude oil’s viscosity and pour point. , Thermal methods consisting of insulating pipelines are considered one of the effective ways to reduce heat losses.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of the Degelation Behavior and Non-Isothermal Flow Restart of a Waxy Oil Pipeline

2023

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Flow assurance challenges associated with waxy crude oil precipitation at low ambient conditions are significant concerns for oil industries during production, transportation, and storage. Numerous methods have been employed to mitigate wax deposition and gelation issues. Since wax precipitation is temperature-sensitive, heating has emerged as a promising method to enhance oil flowability. The present work intends to examine the degelation behavior of waxy oil using rheometry, differential scanning calorimetry, and microscopy techniques. In addition, a non-isothermal flow restart simulation is performed using an in-house numerical simulator consisting of a rheological model of sol–gel transition developed in the current work. A numerical simulation of a preheated gelled pipeline demonstrates the significance of the degelation temperature. The effects of the wax concentration, initial gel temperature, and aging period on the degelation temperature are examined. The observed degelation temperature is higher than the gelation temperature, leading to thermal hysteresis. The extent of thermal hysteresis reduces with a decrease in the heating rate. The numerical simulation uses the finite volume method with variables placed on a staggered grid. The gel heated above and below the degelation temperature shows a significant variation in axial velocity profiles. However, further heating does not affect the velocity profiles. A shear banding type of effect is observed in the axial velocity profile above the degelation temperature. Heating the gelled oil to the degelation temperature instead of the wax disappearance temperature saves excessive heating energy during storage and transport operations.

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Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of the Degelation Behavior and Non-Isothermal Flow Restart of a Waxy Oil Pipeline

2023

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“…98 The yield stress did not change significantly when the application time was increased from 1 to 5 s. A study of simulated waxy oil found that the coexistence of wax and resin/ asphaltene is a necessary condition for the electric field to work; the role of resins and asphaltene content on the electric field modification effect is complex and not a simple monotonic relationship; resin and asphaltene content that is too high will lead to the electric field modification effect becoming worse. 102 The authors summarized the mechanism of electric field treatment to improve the fluidity of waxy crude oil into two aspects: on the one hand, after the electric field effect, the wax crystal particles in the waxy crude oil increase, the particle size distribution becomes wider, and the macroscopic viscosity of the suspension system should be reduced with the same amount of precipitated wax; on the other hand, the charged particles (asphaltenes and resins) in crude oil accumulate on the surface of wax crystals under the electric field effect, which increases the double layer repulsion between wax crystals, weakens the van der Waals forces, and thus improves the flowability of crude oil. However, so far, the effect of electric field modification has been varied widely among different waxy crude oils, the modification effect is unstable, and no electric field treatment has been reported to be able to lower the pour point of crude oils.…”

Section: Strategies For Improving the Flowability Of Waxy Oilsmentioning

confidence: 99%

“…As the electric field strength increased from 0.5 kV/mm to 3 kV/mm, the yield stress decrease rate increased from 50% to more than 90%, and the yield stress decrease trend slowed down when the electric field strength continued to increase; the yield stress decrease rate increased from 60% to more than 90% when the electric field application time increased from 1 to 5 s, and the yield stress did not change significantly when the action time continued to increase . The yield stress did not change significantly when the application time was increased from 1 to 5 s. A study of simulated waxy oil found that the coexistence of wax and resin/asphaltene is a necessary condition for the electric field to work; the role of resins and asphaltene content on the electric field modification effect is complex and not a simple monotonic relationship; resin and asphaltene content that is too high will lead to the electric field modification effect becoming worse . The authors summarized the mechanism of electric field treatment to improve the fluidity of waxy crude oil into two aspects: on the one hand, after the electric field effect, the wax crystal particles in the waxy crude oil increase, the particle size distribution becomes wider, and the macroscopic viscosity of the suspension system should be reduced with the same amount of precipitated wax; on the other hand, the charged particles (asphaltenes and resins) in crude oil accumulate on the surface of wax crystals under the electric field effect, which increases the double layer repulsion between wax crystals, weakens the van der Waals forces, and thus improves the flowability of crude oil.…”

Section: Strategies For Improving the Flowability Of Waxy Oilsmentioning

confidence: 99%

Advances in and Perspectives on Strategies for Improving the Flowability of Waxy Oils

Yao

Sun

et al. 2022

Energy Fuels

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The research on the flowability of waxy oil has spanned more than a century and is still attracting much attention. How to improve the flowability of waxy oil to ensure safe and efficient pipeline transportation and storage is of great practical importance for the industry. In this work, we have systematically reviewed the research advances in improving the flowability of waxy oil. First, the crystallization properties and phase behavior of waxes are described based on their chemical structure, thermodynamic properties, and solution phase properties, with emphasis on the solventized layer properties of wax crystals. Then, the mechanisms, process, and research progress in flow improvement of waxy oil are discussed from three major aspects: process improvement, equipment improvement, and chemical treatment, with emphasis on the summary of waxy oil pour point depressants in recent years. The remaining challenges and perspectives for future research on flow improvement of waxy oil are presented.

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“…Tao et al , tested many crude oil samples under an electric field and found that the electric field is very effective in reducing their viscosities especially at low temperature with very little energy consumption. Ma et al, Huang et al, Chen et al, and Zhang et al studied the influence of electric field on the cold flowability of waxy crude oil. They thought that weakened interaction between wax particles due to electric field exposure should be the primary reason for viscosity reduction.…”

Section: Introductionmentioning

confidence: 99%

Electrorheological Characteristic of Heavy Oil Emulsions under High-Frequency/High-Voltage AC Electric Field

et al. 2023

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We experimentally explored the electrostatic demulsification performance of water-in-heavy oil emulsion under a high-frequency/high-voltage AC electric field by considering some factors such as the shearing rate, water content, temperature, electric field strength, pulsatile frequency, demulsifier types, and concentration. Relative viscosity reduction of heavy oil is used as the evaluation index for demulsification performance. The results indicated that the phase inversion point of the heavy oil emulsion is between 40 and 50%. The demulsification performance can be improved by increasing the shearing rate if it is within the limited range. The optimum shearing rate in this experiment is around 100 s–1 with the corresponding relative viscosity reduction of 64.7%. There exist optimum electric field strength (2 kV/cm) and frequency (2 kHz) for the electrostatic demulsification of heavy oil emulsion with water content 30% and temperature 60 °C. The relative viscosity reduction can be up to 67.5% under optimum electric field parameters (2 kV/cm, 2 kHz). Six different types of demulsifiers used in this experiment all contribute to reducing the viscosity of the heavy oil emulsion. Among them, the type C demulsifier shows the best viscosity reduction effect. The relative viscosity reduction could be up to 76.39% with the combination effect of high frequency/high voltage AC electric field. The viscosity reduction effect is proportional to the demulsifier concentration. These findings can help to optimize operating parameters for the crude oil dehydration devices to achieve best separation performance in heavy oil fields.

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An investigation to the mechanism of the electrorheological behaviors of waxy oils

Cited by 21 publications

References 34 publications

Experimental and Numerical Investigation of the Degelation Behavior and Non-Isothermal Flow Restart of a Waxy Oil Pipeline

Experimental and Numerical Investigation of the Degelation Behavior and Non-Isothermal Flow Restart of a Waxy Oil Pipeline

Advances in and Perspectives on Strategies for Improving the Flowability of Waxy Oils

Electrorheological Characteristic of Heavy Oil Emulsions under High-Frequency/High-Voltage AC Electric Field

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