Case01 Grid Generation
Contents
As discussed in the ParaGeo-Pflotran model building workflows overview, there are several potential workflows to define the geomechanical (ParaGeo) model mesh and the flow model grid (Pflotran / Pflotran-OGS).
In the present case the data used to generate and export the Pflotran-OGS grid is presented. This involves running a ParaGeo data file with a meshed geometry set up in such a way that only the grid export operation is performed (in addition to output plot files to visualize the exported geometry). To this end the data file is set up to run a single time step without any defined loading. Note that the exported Pflotran-OGS grid will correspond to the ParaGeo mesh for the target exported groups. Hence the mesh may be either; generated in ParaGeo in the present workflow step (as demonstrated in the present case) or read from a .geo file which may have been obtained from a 3rd party mesh generator (e.g. Gmsh).
The PFO_001_Case01_GridGen.dat file is provided in PFO_001\Case01_Grid_Gen\Data. The data includes:
1Geometry data (nodal_data, Geometry_line, Geometry_surface and Geometry_volume) for definition of the 3D geometry. This must be defined at the end of the file after the END DATA command.
2Geometry_set data for the model boundaries (not used in the present workflow step).
3Mesh data for defining a structured mesh (Mesh_control_data, Structured_mesh_data and Structured_line_set data structures).
4Group data for the three formations (Group_control_data and Group_data data structures) with "Reservoir" material assigned to the reservoir and "Shale" material assigned to the overburden (shallow_shale) and underburden (deep_shale).
5Material_data and Fluid_properties data structures defining the material properties for the formations. Note that the Porosity and Permeability for the reservoir material are the only key properties in the present workflow step, as they will be exported in eclipse data format.
6Stratigraphy data (Stratigraphy_definition and Stratigraphy_horizon) to identify the top surface of the model (not relevant in the present workflow step).
7Support data (Support_data) defining full fixities (in X, Y and Z) for all the volumes in the geometry using an internally generated Geometry_set "All_volumes".
8Eclipse_export used to define the material properties for which a grid will be exported and to define the origin of the grid (X, Y and Z coordinates corresponding to the origin of the exported groups).
9Pflotran_coupling_data to export eclipse grid data for the reservoir group.
10Control data (Control_data) to run a single step.
Below the key data for grid generation is discussed in detail.
Material data
In the present workflow step only "Reservoir" material porosity and permeability properties are relevant, as those will be exported in eclipse grid data format for input in Pflotran-OGS.
Data File |
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* Material_data NUM=1 ! --------------------------------- Name "Reservoir" (...) ! -------------------------------------------------- Porosity 0.300 ! -------------------------------------------------- Permeability_type 1 Permeability_x 2.961E-13 Permeability_y 2.961E-13 Permeability_z 2.961E-14
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•Porosity is defined with a value of 0.3.
•Transverse isotropic permeability is considered by defining: ▪A vertical permeability (Permeability_z) of 2.961·10-14 m2 (~30 mD) ▪Horizontal permeabilities (Permeability_x and Permeability_y) of 2.961·10-13 m2 (~300 mD). |
Eclipse export data
Eclipse_export data structure is required to define the origin of the exported eclipse grid. In addition it is used to define the properties that will be exported in a grid for input in Pflotran-OGS.
Data File |
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* Eclipse_export ! --------------------------------- Output_file_name "PFO_001_Case01" Property_names IDM=4 "Perm_x" "Perm_y" "Perm_z" "Porosity" Grid_origin IDM=3 /X Y Z / 0.0 0.0 -1350.0
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•The Output_file_name is defined as "PFO_001_Case01".
•The 3 components of permeability as well as porosity values will be exported for each cell in the flow model grid as defined under Property_names keyword.
•In Grid_origin the coordinates of the origin for the flow model grid are defined. In this case the coordinates correspond to a corner in the top of the reservoir. |
Pflotran_coupling_data
Pflotran_coupling_data is set to export eclipse grid data for the reservoir group only.
Data File |
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* Pflotran_coupling_data ! --------------------------------- Groups IDM=1 "reservoir" Output_pflotran_mesh 2 ! 1 ugi, 2 grdecl, 0 no output Output_pflotran_mesh_file_name "PFO_001_Case01" Units_list IDM=4 "stress" "length" "temperature" "density" Units IDM=4 "Pa" "m" "Celsius" "kg/m^3"
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•In the Groups keyword we define the names of the groups that will be considered in the flow model (simulated by Pflotran-OGS) and consequently for which we are exporting the grid.
•Output_pflotran_mesh is set to 2 to output data in Eclipse grid cell format (as required by Pflotran-OGS).
•In Output_pflotran_mesh_file_name the name of the output file containing the grid is defined.
•Units are specified for reference using Units_list keyword to define the physical quantities and Units to define their corresponding units adopted in the data file. |
Results
The results are provided in PFO_001\Case01_Grid_Gen\Results. These consist of:
•PFO_001_Case01_header.grdecl: File defining flow model dimensions (number of cells in X, Y and Z directions) and files to import for the material properties. •PFO_001_Case01_coord.grdecl: File containing the Eclipse grid coordinates (COORD and ZCORN data). •PFO_001_Case01_PERMX.grdecl: File containing values for permeability in X for each cell of the flow model. Note that the values are in mD units, as required for input in Pflotran-OGS. •PFO_001_Case01_PERMY.grdecl: File containing values for permeability in Y (mD) for each cell of the flow model. •PFO_001_Case01_PERMZ.grdecl: File containing values for permeability in Z (mD) for each cell of the flow model. •PFO_001_Case01_PORO.grdecl: File containing values for porosity for each cell of the flow model.
In addition some plot files are exported:
•PFO_001_Case01.plt: Plot file for the ParaGeo model mesh that can be visualised in ParaView by loading the PFO_001_Case01.xmf file . •PFO_001_Case01_GridGen_001.gmr: Geometry plot file for the ParaGeo model that can be visualised in ParaView by loading the PFO_001_Case01_GridGen_gmr_001.xmf file . •PFO_001_Case01_GridGen_orig.ecl : Plot fie for the exported eclipse grid which can be visualised in ParaView by loading the PFO_001_Case01_GridGen_orig_ecl.xmf file. Note that because in Eclipse format depth is positive, the flow model will appear with the Z coordinate mirrored relative to the ParaGeo model.
View of the ParaGeo model mesh
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