Issue 63

Filling Line Logs with Variable Color Fill

One way to display geophysical data is to fill geophysical line logs (such as gamma logs) with a color gradient relative to the data value, or variable.

A popular way to show
geophysical data is with
a variable-filled line log.

To create a line log filled with a variable fill, you can overlay a bar log and a line log. The exact steps are as follows:

Create the Bar Log

1. Open Strater 2 and go to Tools | Log Items | Bar, or click on the toolbar.
2. Click in the log pane where you want the log to be placed.
3. In the Open dialog, select the data file to use for the bar log, such as an LAS file, and click Open. In this example, I will use SB20.las, obtained from the USGS.
4. In the LAS Import Options dialog, accept the defaults and click Load. This loads the data from the LAS file into a data table and creates the bar log from that data.
Create the Color Scheme for the Bars
5. To assign the correct colors to the correct data ranges in the bar log, we need to create a scheme from the data. Click on the data table tab at the top of the window to bring the data table to the forefront. In this example, I will click on the SB20 data table tab.


Click on the data table tab at the top of the window
to open the data table.


6. Right click over a cell in the data column that you want to plot. In this example, right click over a cell in the GR column.
7. Select the Create Scheme option.
8. In the New Scheme dialog, the information is automatically determined by the data column selected. You can change the Scheme Name to something else if you desire, and you can change the Interval Count. In this example, change the Interval Count from 10 to 5. This is the number of bins into which Strater will divide the data.


Define the scheme name and number of scheme items in the
New Scheme dialog.

9. Click OK and the scheme is created.
10. Click back on the borehole view tab to bring the borehole view to the forefront.
11. Select the bar log in the borehole view and in the Property Manager change the Data Column from the default column to the correct data column, if necessary. In this case, change it to GR since that is the data column from which the scheme was created.
12. Set Use Range Scheme to True.
13. Click in the Range Scheme field and select the range scheme you just created, SB20 – GR.

Specify the Colors in the Scheme.

1. Once the range scheme is applied, it appears to be solid black. This is because of the properties applied in the scheme. To change these, go to Tools | Scheme Editor.
2. In the Scheme Editor, click the to expand the Range scheme SB20 – GR. There are 5 items in this range scheme, each with its own drawing properties.
3. Select the first item in this scheme. The properties for that item are displayed on the right side of the screen. You can change the lower and upper range values if you wish.

1. Open the Fill Properties section and change the Fill Properties to be what you want for this data range. For example, click the Foreground color and change it to Forest Green.
2. Open the Line Properties section, click in the Style field and change the line style from Solid to Invisible.

4. Select the next item in the scheme and repeat changing the fill color and setting the line style to Invisible.
5. Click OK when you are done and the changes are applied to the log.

Add the Line Log

1. Now we want to overlay a line log to show a smooth line for the data. Go to Tools | Log Items | Line/Symbol, or click on the toolbar.
2. Click in the log pane.
3. In the Open dialog, select SB20 from the Use Current Table drop down list to avoid importing.
4. Click Open and the line log is created.
5. Select the line log and in the Property Manager, change the Data Column to the same column the bar log uses, GR.
6. To align the line log exactly with the bar log, select both logs log (click on the line log, hold down the shift key and click on the bar log), then go to Arrange | Align Objects | Left. The line log is on top of the bar log and they overlay exactly.
7. In the Object Manager, you can see that under the Header Pane Objects, there are two scale bars. One was created for the bar log, and one was created for the line log. We only need one scale bar, so we can delete the second one. Select the scale bar called Scale Bar – GR.1 and press Delete on the keyboard to delete it.

Add the Finishing Touches

1. Add any additional items to enhance the appearance of the log. For example, you can go to Tools | Log Items | Depth, or click on the toolbar.
2. Click in the borehole view to the right of the overlaid line/bar log and the depth log is added.
3. You can space the depth log right next to the line log by selecting both the line log and the depth log and going to Arrange | Space Objects | Right to Left.
4. You can add grid lines to the log by selecting the bar log, going to the Grid Line tab in the Property Manager and selecting to show the Variable Grid Lines and the Depth Grid Lines. You can choose to show the major and minor grid lines, and set the properties for these grid lines.
5. You can adjust the starting depth of the borehole view by going to View | Borehole View Properties, and in the Property Manager, setting the Depth Settings to User Defined and changing the Starting Borehole Depth to another value, such as 200.

Overlay a line log and a bar log to
show a line log with variable fill.