9️⃣OUTPUTS

TOUGH4 produces a variety of printed output, most of which can be controlled by the user. In the initialization phase TOUGH4 writes out the general information for model setup and other related system information to the standard output file (TMsimulation.log). This is followed by documentation on block-by-block permeability modification, on settings of the MOP- and MOP2-parameters for choosing program options, and on the EOS-module. During execution TOUGH4 can optionally generate a brief printout for Newtonian iterations and time steps. The file TMsimulation.log also includes the volume- and mass-balances at each specified printout times or time step. For MPI simulation, additional log files (additional_TMsimulation1.log, additional_TMsimulation2.log, ...) may be written by other than the master CPU for additional time-stepping/warning information from the corresponding CPU.

TOUGH4 generates output files for pre-defined selection of element, connection, or generation variables based on KDATA in block PARAM (see Table 29) or user specified variables with keyword OUTPU. Separate files in the selected format (either CSV for positive KDATA or TECPLOT for negative KDATA) will be generated for element-, connection-, and sinks/sources-related outputs at user-specified simulation times in block TIMES or time step frequencies in block PARAM.

Table 29. Standard output based on KDATA

abs (KDATA) = 1: a selection of element variables
Output variable	Comment
Pressure
Temperature	Only in nonisothermal mode
Saturation	Saturation of all phases
Mass fraction	Mass fraction of all components in all mobile phases
Relative permeability	Relative permeability of all mobile phases
Capillary pressure	Between mobile phases
Density	Density of all mobile phases
Porosity
Biomass	Biomass of all microbial populations
abs (KDATA) = 2: in addition, a selection of connection variables
Heat flow	Only in nonisothermal mode
Total flow
Phase flow	Flow of all mobile phases
Diffusive flow	Only when "accounting for diffusion" is TRUE, see MODDE.3
abs (KDATA) = 3: in addition, a selection of generation variables
Generation rate	Mass (kg/s) or energy (J/s) rate depending on generation type
Flowing enthalpy	Only in nonisothermal mode
Fractional flow	Only for production
Wellbore pressure	Only for production wells operated on deliverability against specified bottomhole pressure

TOUGH4 allows the user to select the output variables to be printed using block OUTPU. The user can choose any number of element-, connection-, and generation-related output variables. A lumped set of primary variables or secondary parameters can be selected, and other information, such as grid-block or connection coordinates, index of elements, connection, or sinks/sources, and element names, can be included as well. The list of the output variables is shown in Table 18. The header and unit of variables/parameters selected for printout will be generated accordingly.

By default, outputs are printed to both the default standard output file (output_data) and the CSV format files. Users may opt out printing output variables to the standard output file, particularly for large-scale simulations, to avoid creating a very big file. TOUGH4 also offers an option to generate a file in a format suitable for TECPLOT. The output variables written to the standard output file can be extracted for visualization using a reformatting program (such as EXT, a free post-processing program downloadable from the TOUGH website, which parses the standard output file along with spatial information provided in the MESH file and then generates a plot file in a format suitable for visualization, for instance, using TECPLOT). It should be noted that EXT calculates the components of flow vectors at the centers of grid blocks; in the current version of the OUTPU feature, flow rates and velocities are simply printed for each connection.

Time series of some parameters for plotting can optionally be written to files in the CSV file format using input keyword FOFT (for elements), COFT (for connections), GOFT (for sinks and sources), and ROFT (for rocks). TOUGH4 will generate separate files for each element, connection, sink/source, and rocks. TOUGH4 provides options for users to select the parameters to be written out.