Calculating fracture gradient per NCT type

Using the FG from NCT PP form (1D MODEL > Fracture Gradient > FG from NCT PP), you can calculate the fracture gradient per Normal Compaction Trend type.

  1. Overburden Stress  Select the overburden stress log to use in the fracture gradient calculation.

    Select the NCT type that you want to calculate the fracture gradient for and the calculation method.

    (Optional) If you want to calculate the fracture gradient based on the pore pressure obtained from each particular log, select the pore pressure source log type (Density, Acoustic, Resistivity or Velocity) that you want to calculate the fracture gradient for and the calculation method.

    Select calculation method  For each fracture gradient calculation, you select the calculation method. Based on the calculation method selected, you can select a Static Poisson Ratio input and adjust the constant factor for the calculation.

    Stress Factor  Specify the stress factor for the calculation method. The Hubbert Willis and Matthew Kelly methods use a stress factor; the Eaton method is independent of a stress factor and uses the Static Poisson Ratio log (which the other methods do not).

    (Re)Calculate  Click to calculate the fracture gradient. The resulting fracture gradient will appear in the text field below the button. After you make adjustments, click (Re) Calculate again to recalculate the fracture gradient.

    If the lock is green, the (re)calculation is done automatically.

    Fracture Gradient  The name of the resulting fracture gradient log appears in this name field. The log is stored in the JewelExplorer.

    2. To change the default name of the created log, double click in the log field. The background turns blue, indicating you can edit the text. When done, click the green check mark to apply the changes.

  2. Show the calculated NCT type fracture gradients to the associated view.

    Show on FG View  Opens the Fracture Gradient view with the NCT Fracture Gradient and its associated EMW log added as the last two tracks in the view.

    Show on PPP View  Opens the Pore Pressure Prediction view with the NCT Fracture Gradient and its associated EMW log added as the last two tracks in the view.