Theoretical and numerical investigation of the rheology of heavy crude oil

Happy, Fatema Akter (2018) Theoretical and numerical investigation of the rheology of heavy crude oil. Masters thesis, Memorial University of Newfoundland.

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Abstract

The rheological study of heavy crude oil is important in the field of petroleum engineering. The rheological properties of heavy oil (e.g., shear stress, shear rate, viscosity, etc.) depend on several factors including temperature, pressure, surface tension, diluent type and diluent composition, pH, shear stress and thermal histories, memory, and shear conditions during the analysis. The investigation of the rheology of heavy crude oil flow is a critical issue for both upstream and downstream operations. The objective of this study is to perform an investigation on the rheological properties of heavy crude oil to show the effect of shear rate, temperature, and pressure on the viscosity and the shear stress. The aim of this work was to broaden current knowledge of the rheological behavior and flow characterization of heavy crude oil. This paper takes a new look at the shear stress-strain relationship by considering the memory effect along with temperature effect on the shear rate. It is considered that the viscosity of the heavy crude oil is a function of pressure, temperature, and shear rate. As the heavy crude oil is considered as a Bingham fluid, Bingham model is employed here for the analysis. The experimental data from previous studies are used to complete the analysis. To develop the model, a modified Darcy’s law that employs the effect of memory on the Bingham model is considered. The effect of temperature has been incorporated by the Arrhenius equation for the development of a new model to study the heavy crude oil rheological behaviors. The relationship between shear stress and viscosity has been shown at different fractional derivative order and time. The validation and the simulation of the model are performed by using the experimental and the field data from the literature. The numerical simulation of this model is conducted by using the MATLAB simulation software. From the sensitivity analysis, it is found that the temperature has the highest impact on the viscosity over the pressure and the shear rate. On the other hand, the pressure shows a strong effect on the shear stress-shear rate relationship over the temperature. In the model analysis, it is found that the fluid memory affects in the Bingham model due to nonlinear behavior of heavy crude oil. The shear stress increases with decreasing viscosity at different fractional derivative order and time. The change in shear stress is high at large fractional derivative. The range of fractional derivative order is from 0.2 to 0.8. When fractional derivative order,

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