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Numerical Modeling of Density-Driven Flow in Vuggy Porous Media Using Extended Finite Element Method

Mousavi, Mohammad | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55836 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khoei, Amir Reza
  7. Abstract:
  8. The main goal of this research is to investigate the effects of different types of heterogeneities on fluid flow and solute transport in saturated porous media. These heterogeneities are micro- and macro-fractures and cavities. For modeling micro- and macro-fractures we used an equivalent continuum model and extended finite element, respectively. Also, we modeled the problem by using mass conservation law for both components of the problem – fluid flow and the solute – and Darcy’s law. In modeling vuggy porous media, due to the high velocity of the fluid inside the free flow areas i.e. channels and cavities, we could not model the medium properly using Darcy’s law. Therefore, we had to use a more complex equation called the Darcy-Brinkman equation. After that, some parameter studies were performed on the different characteristics of micro-fractures like orientation and aperture, different characteristics of macro-fractures like aperture, and density and diffusion coefficient of the solute. We saw that micro-fractures had a more significant impact on the solute spread in the medium in comparison with macro-fractures. Especially, their orientation and aperture could completely change the pattern of the solute spread. Moreover, cavities and channels acted like a magnet and absorbed the fluid flow, and then, increased its velocity multiple times. Finally, in the last part of this work, a real field in Hungary was modeled. This simulation was related to a heterogeneous salty reservoir containing five different layers with different characteristics and 8 macro-fractures. It has been shown that decreasing the anisotropy of the four top layers can increase the rate of washing saline water from the medium. On the other hand, it was observed that owing to the impenetrability of the bottom of the reservoir, this factor had the opposite effect in the lower layer
  9. Keywords:
  10. Saturated Porous Medium ; Extended Finite Element Method ; Equivalent Continuum ; Microcrack ; Vuggy Porous Media ; Micro and Macro Fractures

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