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Experimental Study and Modeling of Rheological Behavior of Crude Oils and W/O Emulsions in the Presence of Surfactants

Sadeghi, Mohammad Bagher | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42982 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ramazani Saadatabadi, Ahmad; Taghikhani, Vahid; Ghotbi, Cyrus
  7. Abstract:
  8. Understanding the properties of crude oil and the phenomena arising from this precious matter has always been of considerable importance. One of these important phenomena is emulsion, which is well-known in a great number of crude oil-related processes such as drilling, well completion, production, transportation and even the processing units in the refinery. One of the most important properties of crude oils and their emulsions is their flow or in other words their rheology. Therefore, in this project has also been tried to investigate the rheological behavior of crude oil and water in crude oil emulsion, experimentally and theoretically. The experiments were carried out using two crude oils named Soroush and Nowruz as oil phase and several emulsions were synthesized by the deionized water as the water phase and Span-type surfactants as the emulsifier. Important parameters affecting the rheological properties of emulsions were investigated. Some of these important parameters are temperature, shear rate and deformation, dispersed phase volume fraction and the surfactant concentration. The results obtained by microscopic analysis revealed that in the both crude oil samples, phase inversion phenomenon takes place in the range of 40 to 50% of the dispersed phase (water) content. Temperature was found to be a significant affecting factor in all the samples including the crude oils and their emulsions. It was observed that an increase in temperature can cause a considerable decrease in viscosity and dynamic moduli. Increase in water volume fraction caused an increase in viscosity and dynamic moduli up to the phase inversion point and resulted reverse beyond this point. Investigation of shear rate effect demonstrated a Newtonian behavior for the crude oils in a wide range of shear rates and shear-thinning effect for the emulsions. This shear-thinning effect was observed to increase with the increase in water content and surfactant concentration. Results showed a notable increase in viscosity and elasticity of emulsions with the increase in surfactant concentration. In order to compare the experimental results and the conventional models, dependence of emulsion viscosity on key parameters of the dispersed phase volume fraction, temperature and shear rate was investigated. Hence, it was tried to investigate more models that are used in crude oil emulsions. In examining models, it was observed that the Liu model for the dispersed phase volume fraction dependency, the Arrhenius model for temperature dependency and power-law model for shear rate dependency have better compatibility with experimental results.
  9. Keywords:
  10. Crude Oil ; Water-in-oil Emulsion ; Surfactants ; Rheological Properties ; Sheer Thinning

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