Generation of Unstructured Reservoir Grid Conform to Wells and Surfaces.

Xaviere Jidouard and Romain Merland and Guillaume Caumon. ( 2012 )
in: Proc. 32nd Gocad Meeting, Nancy

Abstract

We describe a method to generate Voronoi perpendicular bissector reservoir grids honoring wells trajectory. This method uses a global energy minimization to generate Centroidal Voronoi Tessellations (cvt). The CVT energy is minimized together with a new energy term to ensure the conformity of the grid to wells, whereby grid blocks are centered on the wells. This energy may be combined with other terms in the global optimization, for instance to also ensure grid conformity to geological surfaces. We minimize the global energy functions by two kinds of gradient descent algorithms: the Lloyd’s method, which we apply on Voronoi cells restricted to the well paths, in order to optimize the grid blocks along the well paths only. A steepest gradient adaptive method, for the simultaneous conformity to wells and other features. In the resulting grids, the grid blocks intersected by wells tend to have a prismatic shape with two basal faces being orthogonal to the well. This global optimization method also allows for obtaining facets aligned with the geological surfaces. This opens new perspectives for mixing gridding strategies when generating flexible reservoir grids for flow simulation.

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BibTeX Reference

@INPROCEEDINGS{JidouardGM2012,
    author = { Jidouard, Xaviere and Merland, Romain and Caumon, Guillaume },
     title = { Generation of Unstructured Reservoir Grid Conform to Wells and Surfaces. },
 booktitle = { Proc. 32nd Gocad Meeting, Nancy },
      year = { 2012 },
  abstract = { We describe a method to generate Voronoi perpendicular bissector reservoir grids honoring wells trajectory. This method uses a global energy minimization to generate Centroidal Voronoi Tessellations (cvt). The CVT energy is minimized together with a new energy term to ensure the conformity of the grid to wells, whereby grid blocks are centered on the wells. This energy may be combined with other terms in the global optimization, for instance to also ensure grid conformity to geological surfaces. We minimize the global energy functions by two kinds of gradient descent algorithms:
the Lloyd’s method, which we apply on Voronoi cells restricted to the well paths, in order to optimize the grid blocks along the well paths only.
A steepest gradient adaptive method, for the simultaneous conformity to wells and other features. In the resulting grids, the grid blocks intersected by wells tend to have a prismatic shape with two basal faces being orthogonal to the well. This global optimization method also allows for obtaining facets aligned with the geological surfaces. This opens new perspectives for mixing gridding strategies when generating flexible reservoir grids for flow simulation. }
}