Plugins generated by WizGen in Basic project mode

The plugins _AUTO_THICK_PLUGIN.cpp and _AUTO_PERM_PLUGIN.ccp are automatically generated and stored in the project's "<project_name>_INPUT/.plugins"  directory and included in the TGDATA run file under the TGPLUGIN keyword when the Fault Rock Properties settings are saved via WizGen in Basic project mode.

WizGen in Basic project mode generates different forms of PERM plugin depending on which of the three fault permeability model options is selected, whereas the form of the THICK plugin is the same for all models. The constants used in both the THICK and PERM plugins are read from the Fault Rock Properties page and substituted into the plugin codes. Correspondingly, when WizGen is started in Basic project mode, the constants currently in the plugins are loaded into the Fault Rock Properties page.

THICK plugin

The code generated for the THICK plugin by WizGen in Basic project mode and stored in the file `_AUTO_THICK_PLUGIN.cpp' is:-  

// This plugin code was generated by WizGen
// to compute fault thickness

// PLEASE DO NOT EDIT THIS FILE BY HAND

double const_min_displ = 0.001;
double const_a = 0.005882;
double const_b = 1;

if (v.displ < const_min_displ) {
  v.thick = const_a * pow(const_min_displ, const_b);
}
else {
  v.thick = const_a * pow(v.displ, const_b);
}

Where `a' and `b' are substituted from the Displacement to Thickness constants set on the Fault Rock Properties page.

PERM plugin calculated from CSP only

The code generated for the PERM plugin by WizGen in Basic project mode when calculating Fault permeability as a function of Only CSP and stored in the file `_AUTO_PERM_PLUGIN.cpp' is:-  

// AUTO_PLUGIN_TYPE:CSP_ONLY

// This plugin code was generated by WizGen
// to compute fault permeability

// PLEASE DO NOT EDIT THIS FILE BY HAND

double const_cutoff = 5;
double const_a = 0.4;
double const_b = 4;
double const_c = 0.25;
double const_d = 5;

double perm1, perm2;

if (c.dir == DIR_X) {
  perm1 = up.permx;
  perm2 = down.permx;
}
else {
  perm1 = up.permy;
  perm2 = down.permy;
}

// vertex permeability set to zero if csp greater than cutoff or csp undefined
if (v.csp > const_cutoff || v.csp == UNDEFINED_VALUE) {
  v.perm = 0.0;
}
// set vertex permeability to harmonic average of the two grid-block perms
else {
  v.perm = 1.0 / ((0.5 / perm1) + (0.5 / perm2));
}

where `cutoff' is substituted from the CSP cutoff value input by the user on the Fault Rock Properties page of WizGen in Basic project mode.

NOTE:- The other constants defined in this plugin are not used in the calculations.

Using the Only CSP setting, the Fault permeability is set to zero when the calculated CSP value is greater than the user-specified CSP cutoff (i.e. clay smear thicknesses greater than the cutoff value are assumed to be totally sealing). Otherwise, the fault permeabilities are set to the average of the unfaulted Permeabilities on either side of the fault.

PERM plugin calculated from SGR only

The code generated for the PERM plugin by WizGen in Basic project mode when calculating Fault permeability as a function of Only SGR and stored in the file `_AUTO_PERM_PLUGIN.cpp' is:-  

// AUTO_PLUGIN_TYPE:SGR_ONLY

// This plugin code was generated by WizGen
// to compute fault permeability

// PLEASE DO NOT EDIT THIS FILE BY HAND

double const_cutoff = 5;
double const_a = 0.4;
double const_b = 4;
double const_c = 0.25;
double const_d = 5;

double term1 = const_a - const_b * v.sgr;
double term2 = const_c * pow(1.0 - v.sgr, const_d);
v.perm = pow(10.0, term1 - term2);

The values of the constants are read from the SGR options on the Fault Rock Properties page of WizGen in Basic project mode.

The TransGen version 3 WizGen in Basic project mode uses the following expression (without dependence on fault rock displacement) for calculating permeability from SGR values based on the compilation of data by Manzocchi et al. (1999) - see Fault Permeability Calculation in the Technical Description of what TransGen does:-

PERM plugin calculated from CSP, then SGR

The code generated for the PERM plugin by WizGen in Basic project mode when calculating Fault permeability as a function of CSP then SGR and stored in the file `_AUTO_PERM_PLUGIN.cpp' is:-  

// AUTO_PLUGIN_TYPE:CSP_THEN_SGR

// This plugin code was generated by WizGen
// to compute fault permeability

// PLEASE DO NOT EDIT THIS FILE BY HAND

double const_cutoff = 5;
double const_a = 0.4;
double const_b = 4;
double const_c = 0.25;
double const_d = 5;

// vertex permeability set to zero if csp greater than cutoff or csp undefined
if (v.csp > const_cutoff || v.csp == UNDEFINED_VALUE) {
  v.perm = 0.0;
}
// set vertex permeability based on vertex sgr
else {
  double term1 = const_a - const_b * v.sgr;
  double term2 = const_c * pow(1.0 - v.sgr, const_d);
  v.perm = pow(10.0, term1 - term2);
}

The values of the constants are read from the Fault Rock Properties page of WizGen in Basic project mode.

If the Fault permeability option CSP then SGR is selected, both these FSPs are calculated and the fault permeability calculation is a hybrid of these two methods, i.e. if the CSP at a connection is lower than the user-specified CSP cutoff, the fault permeability is calculated as a function of SGR using the expression given above. While if the CSP is greater than the cutoff (i.e. clay smear thicknesses greater than the cutoff value are assumed to be totally sealing), the fault permeability is set to zero.