Exercise 9: Derivative Smoothing

This exercise demonstrates how to use the derivative analysis and diagnostic plot features available in AquiferTest to help identify aquifer conditions and facilitate method selection for type curve matching. The AquiferTest project used in this exercise has already been created for you.

This exercise is written with the assumption that you have gone through the Quick Start Demo Tutorials, and are familiar with the AquiferTest interface.

NOTE: Derivative Analysis tools are only available in the AquiferTest Pro edition.

[1] Start AquiferTest and click on the (Open other project...) button, or if AquiferTest was already started then select File/Open from the main menu.

[2] Browse to the folder: "C:\Users\Public\Documents\AquiferTest Pro\Exercises\", and select the project: Moench Fracture Skin.HYT

[3] Click the [Open] button

This pumping test consists of a fully penetrating pumping well and an observation well located 110 meters away.

[4] Once the project has loaded, select Analysis > Create a New Analysis from the main menu

[5] In the Data from list, uncheck the UE-25b#1 (Pumping Well) so that only the UE-25a#1 is selected

[6] Select the Diagnostic Graph tab to view the drawdown over time in log-log format. The diagnostic graph should look like the image below:

As you can see, this diagnostic plot does not really give a clear indication of conditions of the aquifer system. In other words, it cannot be easily matched to one of the diagnostic plot templates along the right side of the Diagnostic Graph. To help determine the appropriate aquifer conditions, you will apply derivative smoothing to the curve.

[7] Click the Derivative... button in the Diagnostic Graph toolbar to open the Derivative Settings dialog

[8] Select the Set each dataset separately option

[9] From the Method combo box, select the Bourdet Derviate (BOURDET 1989) method and 0.1 for the L-Spacing. The Derivative Settings window should look like the image below:

[10] Click the [Ok] button to apply the settings. The derivative data was not improved significantly. As you can see from the image below, there has been little to no change in the diagnostic graph:

The graph can be further enhanced by increasing the L-Spacing of the derivative method.

[11]  Click the Derivative... button in the Diagnostic Graph toolbar to reopen the Derivative Settings dialog

[12] Change the L-Spacing value to 0.5

[13] Click the [Ok] button

With the additional smoothing, the diagnostic graph clearly reveals unconfined or double porosity aquifer conditions, as highlighted in the image above. Based on your knowledge of the site (through field investigations, drilling and well completion logs, geologic reports, etc.), you may determine whether the diagnostic graph is more representative of dual porosity conditions or of an unconfined aquifer.

This completes the derivative smoothing exercise. The next exercise will demonstrate how to analyze pumping test data from horizontal wells. You have the choice of exiting AquiferTest or continuing on to the next exercise.

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