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Fully Coupled Numerical Modeling Of CO2 Sequestration in Deep Underground Formations with EFG Method

Roghangar, Khatereh | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53386 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Pak, Ali
  7. Abstract:
  8. Greenhouse gas emissions into the atmosphere have multiplied with the increase in fossil fuel consumption, which directly affects global warming. Global warming has other undesirable consequences such as rising sea water level and declining snow cover. To reduce greenhouse gases in the atmosphere, researchers have studied various ways, one of which is carbon dioxide injection into underground formations, which has a significant effect on reducing the amount of these gases in the atmosphere. Existence of high volume underground reservoirs with suitable conditions for gas injection to prevent gas escape has made it a widely used and effective method. Despite many advantages of this method, it has a number of geotechnical-related effects such as injection-induced microseismicity, caprock failure, and surface uplift, which are currently being studied by researchers. The purpose of this study is numerical modeling of carbon dioxide sequestration in saline reservoirs or depleted oil / gas reservoirs using Element-Free Galerkin (EFG) method in a fully coupled Thero-Hydro-Mechanical manner considering two immisibale fluids. The numerical approach used in this research is based on simultaneous solving of four governing partial differential equations, including the momentum balance equation for the whole mixture, the mass balance (continuity) equation for each fluid phase, and the energy balance equation (including conductive and convective terms) for thermal effects. Generalized Darcy’s law has been employed for both fluids to satisfy the momentum balance for each of the fluids. The weak form of the governing equations is obtained using the Galerkin method and the essential boundary conditions are applied using the penalty method. It was necessary to construct the variational formulation of the governing partial differential equations for discretization of the spatial domain by considering the solid phase displacement, wetting and non-wetting fluid phase pressure, and temperature as the main variables using the EFG shape functions in place. Discretization in time is carried out using finite difference technique with a fully implicit approach. The model performance is evaluated by solving various problems and comparing the numerical results with analytical solutions, laboratory measurements, and values reported by other numerical modelings. The results indicate that the computer program prepared based on the EFG mesh-free method is capable of modeling CO2 sequestration problems with very good accuracy. The parametric study reveals that with increasing the permeability of the reservoir the amount of surface uplift decreases, however, increasing the permeability of the caprock can intensify the surface uplift.
  9. Keywords:
  10. Gas Injection ; Carbon Dioxide Injection ; Element Free Galerkin Method (EFGM) ; Meshless Method ; Two Phase Fluid Flow ; Thermo Hydromechanical Analysis ; Fully Coupled Analysis ; Carbon Dioxide Sequestration

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