Rock Dependent Constants form

The Rock type dependent calculation method allows you to specify a different fracture gradient and horizontal stress calculation method for each rock type present. On the Rock Dependent Constants form, opened via the Custom FG or Input Definition form by clicking Edit when the <rock type dependent> calculation method is selected for the fracture gradient or horizontal stress, the available rock types are listed in the left window. Select a rock type and specify the required equation type and the relevant input parameters.

Selecting an equation type

You can select one of the available Equation Types (Hubbert Willis, Matthew Kelly, Eaton, or Eaton (KO)) or create an equation yourself by selecting User defined as the Equation Type (see Daines, elastic and plastic equations in Theory and equations), and creating a formula with the mathematical calculator functions that become available, specify the output unit, specify a Name and press Create. The name is added to the Equation Type list and appears in the Equation Type field.

Depending on the parameters that occur in the formula of the Equation Type, you might need to select input parameters.