A mechanistic understanding of the water-in-heavy oil emulsion viscosity variation: effect of asphaltene and wax migration

Piroozian, A ; Sharif University of Technology | 2021

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  1. Type of Document: Article
  2. DOI: 10.1016/j.colsurfa.2020.125604
  3. Publisher: Elsevier B.V , 2021
  4. Abstract:
  5. The role of emulsions as a prevalent phenomenon is broadly investigated in the petroleum industry since forming the emulsion has many severe harmful implications. Heavy components of crude oil such as wax and asphaltene make the water-in-oil (w/o) emulsion more stable, while the role of these components on the emulsion viscosity has not been fully understood. In this regard, to find a proper demulsifier to break these emulsions, it is necessary to know the mechanisms of emulsion formation by heavy oil components. In this study, the effects of waxy-oil and asphaltenic-oil on w/o emulsion were investigated by measuring volume and viscosity of the formed emulsion after an elapsed time, followed by proposing a viscosity model based on experimental data. For this purpose, two types of crude oil were used: asphaltenic oil and waxy oil. Next, the emulsion stability and phase separation in these samples were studied, and viscosity for each segment was measured and modeled in the system. Results showed that phase separation and emulsion formation depend on the presence of asphaltenic-oil and waxy-oil after the passage of a specific time such that the system exhibits a strong function of asphaltene rather than wax. Also, free oil volume decreased with increasing water cut to 70%, where most declines occurred at a stirring rate of 1200 rpm in the presence of asphaltene. Besides, the viscosity of the free oil decreased with increasing water cut to 70% in both waxy-oil and asphaltenic-oil systems such that the free oil viscosity decreased from 11.43 cp to 5.89 cp when the water cut increased from 0% to 70%. Findings also showed that the viscosity of the w/o emulsion phase decreased with increasing the shear rate and temperature, resulting in increased stability in the emulsion. Based on a proposed viscosity model, the model results showed a dispersed oil-in-water (D O/W) flow for the highest water cut of 70% with an average deviation of 7.03% and revealed an accurate estimation to the experimental data. The model approach can be applied in the estimation of the water-in-heavy oil emulsion viscosity in pipelines. © 2020 Elsevier B.V
  6. Keywords:
  7. Asphaltenes ; Crude oil ; Emulsification ; Emulsions ; Heavy oil production ; Ostwald ripening ; Phase separation ; Viscosity ; Accurate estimation ; Average deviation ; Emulsion formation ; Emulsion stability ; Heavy-oil emulsions ; Viscosity modeling ; Viscosity variations ; Water in oil emulsions ; Petroleum industry ; Asphalt ; Paraffin ; Petroleum ; Water ; Crystallization ; Emulsion ; Energy ; Flow measurement ; Phase separation ; Priority journal ; Shear rate ; Shear stress ; Surface property ; Temperature ; Velocity ; Viscometry ; Viscosity ; Volume
  8. Source: Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 608 , 2021 ; 09277757 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0927775720311973