1D GM calculator example - Lithology Model

Using two or more sets of cutoff values in the Lithology Model

In some instances you may want to discriminate values in your Lithology Model based on more than just one set of cutoff. This can be achieved using a custom script in the Property Calculator that produces a lithology log. After creating the property you can assign rock types to the different classes created by the custom cutoff.

1. Open the Property Calculator (Tools > Property Calculator)
2. In the top right corner of the calculator, type in a name for the log.
3. Select Lithology as the property type.

4. Type in an expression that will create the desired cutoff values. An example of such an expression is provided below (and can be copied and pasted into the Expression window):

   if TVD > 1500 then

   if $Gamma Ray Composite (PPP Case)$ < 25 then 1

   else if $Gamma Ray Composite (PPP Case)$ < 75 then 2

   else 3

   else if TVD > 1000 then

   if$Gamma Ray Composite (PPP Case)$ < 23 then 4

   else if$Gamma Ray Composite (PPP Case)$ < 60 then 5

   else 6

   else null

   This expression can be modified or expanded to fit the scope of your analysis.

5. Click Apply to create the log. The new log can be found in the JewelExplorer in the Well Data > All Logs > Lithology folder.
6. After the log has been created, return to the Lithology Model form and open the Zonation Model view (1D Model > Lithology). In the form, select the Calculate from lithology log option and pick the newly created log in the drop down box. Notice that the lithology column in the Zonation Model remains blank.
7. Click the Show button to open the Lithology Property Editor. Assign a rock type to each of the classes created by your expression. Click OK to apply the rock types to the view.