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Thermo-Hydro-Mechanical Modeling of Fractured Deformable Porous Media with Two-phase Fluid Flow using XFEM Technique

Mortazavi, Mohammad Sadegh | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51224 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khoei, Amir Reza
  7. Abstract:
  8. In this study, a fully coupled thermo-hydro-mechanical model for two-phase fluid flow and heat transport in fractured/fracturing porous media is introduced using the extended finite element method (XFEM) for numerical solution. The subject is important in the environmental and industrial fields such as hydraulic fracturing in petroleum industry, CO2 geo-sequestration, geothermal energy extraction and radioactive waste disposal in unsaturated porous media. In the fractured porous media, there are couplings of traction and heat and mass transfer between the fracture space and the surrounding media. Therefore, consideration of the fracture geometry explicitly in the modeling is important to achieve accurate results. The wetting and non-wetting fluid phases studied here are water and gas respectively, which are assumed to be immiscible. In addition, no phase-change is considered here for the fluid phases. The system of coupled equations consists of linear momentum balance equation of solid phase, wetting fluid continuity, non-wetting fluid continuity and thermal energy conservation equations. The main variables used to solve the system of equations are solid phase displacement, wetting fluid pressure, capillary pressure and temperature. Strong discontinuity for solid phase displacement field and weak discontinuity for the other three fields are assumed. A monolithic way of spatial discretization is used for the governing equations of fracture space and the surrounding media. Only the mode I of fracture propagation is studied here using a softening cohesive crack model. The verifications show a good agreement between the results of this study and those of the existing literature. The results show that the effects of thermal stress on effective stress can influence the fracture propagation speed and crack mouth pressure in hydraulic fracturing process. Also, they show the effect of thermal loading on fracture opening and fluids flow in unsaturated porous media
  9. Keywords:
  10. Unsaturated Porous Media ; Two Phase Fluid Flow ; Heat Transfer ; Extended Finite Element Method ; Crack Propagation ; Coupled Thermohydromechanical (THM)Analysis

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