PetraSim reads the TOUGH output files to make plots of results. The user can make 3D or time history plots of the data. When a plot is displayed, selecting File/Export Data... will allow the user to export the current plot data in either Tecplot or spreadsheet format.
To make a 3D plot of results, select Results->3D Results... or 
. This will open a new window with a display of the model and pressure isosurfaces at the first output time, Figure 13.1.
Plot controls include:
Time (s) - A window that displays all the available output times. Select one of these times for plotting.
Scalar - Select the output parameter for plotting. The scalar parameter is the one that will be used for isosurfaces and contours on slice planes. The list of parameters is dynamically created from the TOUGH output file and will be different for each EOS.
Vectors - If vector data was written to the output (this must be selected as one of the Output Controls options), this will display a list of available vector data. The list of parameters is dynamically created from the TOUGH output file and will be different for each EOS.
Show Isosurfaces - This checkbox turns on the display of isosurfaces for the selected scalar. The number indicates how many isosurfaces will divide the plot range. Selecting the Scalar Properties... button displays a dialog, Figure 13.2, on which you can specify a specific plot range, choose to use a logarithmic scale, and specify the number of colors used on contour plots.
Show Vectors - If vector information is available, selecting the checkbox will turn on the display of vector data, Figure 13.3. The Vector Scale, controls the scaling factor applied to the vectors and the Vector Size Range controls the relative size of the longest to shortest vectors. By default, both the relative size and color of the vectors correspond to the magnitude of the vector. Moving the Vector Size Range to the left will result in all vectors having the same length. Selecting the Vector Properties... button displays a dialog, Figure 13.4, in which the user can set the range for vectors and choose whether the vector color should indicate the magnitude.
Show Slice Planes - Turns on slice planes on which contours of the scalar parameter are displayed. Select the Slice Planes... button to define the axes normal to the planes and the coordinates of the planes, Figure 13.5. Typical plots are shown in Figure 13.6
Select File->Export Data... to write a file that can be read into Tecplot. The format of the data will be a value and then the X, Y, and Z coordinates. The data can be written either at the center or corners of each cell.
To make a time history plot, select Results->Cell History Plots... or 
. This will open a new window, Figure 13.7.
You can select the Variable to plot and the Cell Name of the cell. The Cell Name is the name given in the Grid Editor to that cell. Time history plotting for a cell is also activated in the Grid Editor.
By default, only the cells for which time history data have been requested or which have been given a name are listed. However, you can select View->All Cells to expand the list to all cells. When all cells are selected, data will only be available at the times in the standard output file. For cells for which time history output was specified, the results are available at each time step.
This section explains the flow plots created by PetraSim and how to obtain time histories of cells that have sources/sinks.
The model used as an example represents production from a highly permeable layer at about 500m depth (average P = 5 MPa, constant T = 25 ºC, single-phase conditions). The model uses EOS1 and extends for 500x500x20m with a grid of 10x10x4 cells. An initial hydrostatic solution was run. In the production run, two of the boundaries are set to a fixed state and cell 169 uses a “Well on Deliverability” condition with a Productivity Index of 6.0E-9 and a Pressure of 5.0E6 Pa.
Probably the most important piece of information for a source/sink is the flow rate into/out of the cell. This can be plotted by selecting Results->Source/Sink Plots..., Figure 13.10. To make this plot, the Y Scale Range was adjusted to Min Y = -135.2, Max Y = 0.0 (use View->Range...V). This plot indicates that the production rate is 135.0 kg/sec. The user can export the plot.
The user can also obtain this information by looking at the TOUGH2 output file. At the end of every printed time step, the source/sink data is given, as shown below. This data shows that the generation rate is -135.0 kg/s, which matches the PetraSim plot.
TOUGH2 Analysis
KCYC = 20 - ITER = 1 - TIME = 0.63070E+08
ELEM SRC INDEX GENERATION RATE ENTHALPY X1 X2
(KG/S) OR (W) (J/KG)
169 1 1 -0.13500E+03 0.10940E+06 0.10E+01 0.00E+00
To understand the cell history flow plots it is necessary to know the cell names and connections. Figure 13.11 shows the cells names and how they are physically connected for the cells adjacent to cell 169. The production cell is 169 and it is connected to adjacent cells in layer 2 and to cell 48 in layer 1 and cell 290 in layer 3.
We will first focus on the flow plot for cell 170, since that is the simplest. The user can select Results->Cell History Plots..., then select View->All Cells..., and select FLOF(X) for cell #170 to see the to see the plot shown in Figure 13.12. Select File->Export Data... to view the numerical value of -0.029 kg/s-m2.
The flow data plotted in the Cell History plot is the flux averaged at that cell. If we go to the output file, we can obtain the actual values of flow for each connection. A part of the file is shown below.
EL1 EL2 INDEX FLOH FLOH/FLOF FLOF FLO(GAS) FLO(AQ.) FLO(WTR2)
(W) (J/KG) (KG/S) (KG/S) (KG/S) (KG/S)
169 170 385 0.107373E+07 0.109403E+06 0.981440E+01 0.000E+00 0.981440E+01 0.000E+00
170 171 386 0.513309E+06 0.109404E+06 0.469187E+01 0.000E+00 0.469187E+01 0.000E+00
171 172 387 0.340934E+06 0.109404E+06 0.311627E+01 0.000E+00 0.311627E+01 0.000E+00
172 173 388 0.268545E+06 0.109405E+06 0.245460E+01 0.000E+00 0.245460E+01 0.000E+00
173 174 389 0.233448E+06 0.109405E+06 0.213379E+01 0.000E+00 0.213379E+01 0.000E+00
For the connection between cells 169 and 170, the flow is 9.81 kg/sec. For the connection between cell 170 and 171, the flow is 4.69 kg/sec. To calculate the average X flux at cell 170, we average the two flows and divide by the area between the cells (250m2 since the cell face width is 50m and the cell height is 5m). The resulting value is 0.029 kg/s-m2, which matches Figure 13.10.
In the plot the negative sign indicates that the X flux is in the negative X direction. This is consistent with the positive connection sign convention used by TOUGH2. For a connection between cell 1 and cell 2, a negative FLOF indicates a flow from cell 1 to cell 2. A positive FLOF indicates flow from cell 2 to cell 1.
We now look at the more complex case of flow into cell 169, which is a production cell. The user can select Results->Cell History Plots... and select FLOF(X) to see the plot shown in Figure 13.13. This is a graph of fluid flux in the X direction at cell 169. The value is -0.00368 kg/s-m2, which value can be displayed by selecting File->Export Data....
If we look in the output file, we will find the following data for the connections, Figure 13.14.
Using these values and the sign convention for flows, the flows into cell 169 are represented in Figure 13.15.
If we sum these flows, the total is 135.0 kg/sec, consistent with previously discussed source/sink data.
This also illustrates why the flux data for a source/sink cell is not very useful. Since this cell is a production cell, there is flow in from the left and in from the right. The average X flux is then ((7.97-9.81)/2)/250 = -0.00368 kg/s-m2, which matches Figure 13.13.
Thanks to Hildenbrand Alexandra for providing this model.