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Reservoir Flow Simulation Using Multi-Scale Uscaling Method

Ashjari, Mohammad Ali | 2009

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 39326 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firoozabadi, Bahar
  7. Abstract:
  8. This thesis introduces a fast and accurate two-phase reservoir flow simulation procedure. The speed up is achieved by an upscaling technique where coarsening is applied to the detailed geological reservoir descriptions. This process results to two major error sources affecting the simulation accuracy significantly. The homogenization error is appeared when coarse scale data, such as equivalent permeability, is calculated from the available fine grid model information. It is shown that the error can be reduced adjusting coarse grid (non-uniform Cartesian) distribution. For the first time in this study, the grid distribution optimization is done based on “vorticity” map. In particular, the coarse grid is generated in a manner that the vorticity of fine grid model is better preserved by the coarse grid model. To achieve this purpose, the vorticity of single-phase flow is sufficient and the structure of coarse grid is optimized as a pre-processing step without additional computations during the two-phase simulation. Comparison the performance of generated grid based on vorticity with the available permeability- and flow-based grid generation techniques is revealed that the new method has great promises in reducing the error due to homogenization. The specific achievement of the present thesis is application of optimized coarse grid in conjunction with dual mesh method (DMM), as a kind of multi-scale methods. The obtained combined method can efficiently control the numerical errors as a result of grid coarsening. In fact, DMM approximates fine flow from the obtained coarse scale simulation results. Hence, the simulation is actually takes place on the fine scale without solving the relevant flow equations in this scale. Finally, the proposed combined method is examined against 2D and 3D highly heterogeneous models including very long tortuous high permeability channels. The method performance is shown to be almost independent of two-phase flow parameters e.g. mobility ratio and flow regime (viscous or gravity dominated) in a wide range. In addition, for some models, the combined method is ten times faster than the fine grid simulation which is surprisingly high for the achieved high accuracy of the method
  9. Keywords:
  10. Simulation ; Oil Tanks ; Gravitation ; Upscaling ; Dual Mesh Simulation ; VORTICITY

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