Stress computation on unstructured geological grids using Finite Elements Method

Antoine Mazuyer and Arnaud Botella and Marianne Conin and Richard Giot. ( 2014 )
in: Proc. 34th Gocad Meeting, Nancy, ASGA

Abstract

Subsurface stress computation is useful for understanding and predicting mechanical problems such as hydraulic fracturation, borehole stability or initiation and propagation of seismic rupture. The Finite Element Method is a numerical technique for solving these mechanical problems. We present how a unstructured conformal geological grid combined with a software using Finite Element Method can compute the stress. To run these numerical simulations, geomechanical properties such as fault friction are needed. The different faults block have to be clearly defined in the mesh for setting up the numerical problem and visualizing the possibly discontinuous displacement field across the faults. The Finite Element Method also needs boundary conditions so the boundary surfaces of the geological model must be expressed as an input of the software. Then, the stress is computed using a Finite Element software. The computation performance for a tetrahedral grid and a hex-dominant grid is compared: for the same resolution, a hex-dominant grid produces results less precise than a tetrahedral grid, but the computation time is faster because there are less equations to solve.

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BibTeX Reference

@INPROCEEDINGS{,
    author = { Mazuyer, Antoine and Botella, Arnaud and Conin, Marianne and Giot, Richard },
     title = { Stress computation on unstructured geological grids using Finite Elements Method },
 booktitle = { Proc. 34th Gocad Meeting, Nancy },
      year = { 2014 },
 publisher = { ASGA },
  abstract = { Subsurface stress computation is useful for understanding and predicting mechanical problems such as hydraulic fracturation, borehole stability or initiation and propagation of seismic rupture. The Finite Element Method is a numerical technique for solving these mechanical problems. We present how a unstructured conformal geological grid combined with a software using Finite Element Method can compute the stress. To run these numerical simulations, geomechanical properties such as fault friction are needed. The different faults block have to be clearly defined in the mesh for setting up the numerical problem and visualizing the possibly discontinuous displacement field across the faults. The Finite Element Method also needs boundary conditions so the boundary surfaces of the geological model must be expressed as an input of the software. Then, the stress is computed using a Finite Element software.
The computation performance for a tetrahedral grid and a hex-dominant grid is compared: for the same resolution, a hex-dominant grid produces results less precise than a tetrahedral grid, but the computation time is faster because there are less equations to solve. }
}