Upscale simple statistics

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cpchop is a command line utility for doing subsampling and property analysis of Eclipse grid files, typically generated in SBED or ReservoirStudio, but can be used on all corner point grids with box shape and vertical pillars.

The progams picks (optionally random) subsamples from the model and analyzes these. There are a variety of different properties to analyze for each submodel, the most common being single phase permeability (flow based upscaling equivalent to the stand alone tool upscale_perm and bulk properties like porosity and ntg. Results from this kind of analysis can be outputted to a resultfile.

The program can also output the subsamples them selves into new stand alone corner point grids in grdecl format.

Usage

The program can currently only be run from a Linux command line. Follow these instructions for access to the binary files.

$ cpchop gridfilename=cornerpointgrid.grdecl [option=value]

The gridfile must have a shoebox shape with vertical pillars.

Option Description Default value
subsamples number of subsamples 1
filebase If supplied, grdecl-files for each subsample will be written to files named using this filebase, it may include directory names
resultfile name of a textfile to output table of results pr. subsample to
ilen length in i-direction of subsample, specified in number of cells(!) all cells in i-direction
jlen length in j-direction of subsample, specified in number of cells(!) all cells in j-direction
zlen length in z-direction of subsample, specified in the grids length unit (typically cm or m) full height
imin can be used to limit the search area for random subsamples minimum i in inputgrid (full model)
imax can be used to limit the search area for random subsamples maximum i in inputgrid (full model)
jmin analog to imin, but in j-direction minimum j in inputgrid (full model)
jmax analog to imax, but in j-direction maximum j in inputgrid (full model)
zmin analog to imin, but in z-direction and specified in the grids length unit minimum in inputgrid
zmax analog to imax, but in z-direction and specified in the grids length unit maximum in inputgrid
upscale boolean for whether to do upscaling on the subsamples, either true or false. If the objective is to obtain a grdecl-file for the subsample, set to false for run time. true
bc boundary condition type for upscaling, either fixed or periodic fixed
resettoorigin If true, outputted grdecl-file will have its ZCORN-values and COORDS-values shifted so that the model is defined at the origin. If false, the outputted grdecl-file will be located in its original position. true
seed
z_tolerance
minperm
dips
azimuthdisplacement
satnumvolumes
mincellvolume
endpoints
cappres
rock_list
anisotropicrocks


Output:

  • If wanted, each subsample is outputted to a grdecl-file that can be analyzed further
  • A list of upscaled porosity and permeability for each subsample

Example

$ cpchop gridfilename=HugeReservoirStudioGrid.grdecl subsamples=100 ilen=5 jlen=5 zlen=5


Command line options

  • gridfilename - grdecl filename to be analyzed
  • subsamples - number of subsamples. Default 1.
  • resultfile - name of a textfile to output table of results pr. subsample to
  • filebase - If supplied, grdecl-files for each subsample will be written to files named using this filebase, it may include directory names.
  • ilen - length in i-direction of subsample, specified in number of cells(!). Default is all cells in i-direction.
  • jlen - length in j-direction of subsample, specified in number of cells. Default is all cells in j-direction.
  • zlen - length in z-direction of subsample, specified in the grids length unit (typically cm or m). Default is full height.
  • imin and imax - can be used to limit the search area for random subsamples.
  • jmin, jmax, zmin and zmax - vice versa. These values default to the whole grid.
  • upscale - a boolean for whether upscaling is to be done on the fly, either true or false. True by default. Set this to false if your objective is to obtain a grdecl-file for the subsample.
  • bc - boundary condition type for upscaling, either fixed or periodic. Default is fixed.
  • seed - an integer to be used for seed for random number generator. Default is to pick a seed from current time.
  • z_tolerance - points on the same pillar will degenerate to a single point when z-coordinates are within z_tolerance. Default to zero. Can be helpful for permeability upscaling on subsamples when it fails to converge.
  • resettoorigin - If true, outputted grdecl-file will have its ZCORN-values and COORDS-values shifted so that the model is defined at the origin. If false, the outputted grdecl-file will be located in its original position. Default is true.
  • satnumvolumes - if true, relative volumes pr. SATNUM is also calculated.
  • dips - if true, dips are also measured for subsamples, see Res:Grdecldips. Outputted values are dip and azimuth for each subsample.
  • azimuthdisplacement - if dips are true, this can be used to add displament to the outputted azimuths. If left 0 (default), the azimuth will be relative to the grid.
  • mincellvolume, if dips are true, this is used to avoid cells within subsamples for the dip calculation. Default 1e-8.
  • endpoints - if true, saturation endpoints are calculated. A list specifying input saturation data for each rock type must also be given.
  • rock_list - A file with a list of one file per satnum specifying two phase properties for each rock type

NB: If bundary condition type (bc) is periodic, the subsample must be at least 3 cells in each direction, i.e. ilen and jlen must be 3 or larger and zlen must be set large enough to include at least 3 layers.