## ESTIMATE THE END OF WELL-BORE STORAGE EFFECTS

Select the ANALYSIS pull-down menu in PIE and select the "DIAGNOSTIC"
option. This will display a set of graphics functions (the floating
'toolbar' at the bottom of the main window) that allow you to
draw lines on the plot.

It is not possible to make a reliable estimate of the storage
coefficient when the data does not show a unit-slope or the well-bore
storage coefficient is changing. In this case, the time at which
well-bore storage effects end should be estimated by entering
a calculated storage coefficient. Follow these steps to enter
the C(min) value we calculated earlier:

- Select the button for the UNITSL function.

- Pick any point to the left of the data on the derivative plot

- Turn off the UNITSL function by clicking on the button again.
(Note how the button pushes in and out).

- Use the mouse to click on the "well. Storage" value
shown on the plot. Note the prompt to enter a new value at the
top of the plot: enter the value of C(min) calculated previously.

The end of well-bore storage effects is calculated from the C(min)
value and a vertical line is drawn to show this time on the plot.
The end result of these steps should look something like this:

WRITE DOWN the number of log-cycles on the time axis between the
"ENDWBS" line and the end of the test data (the above
figure shows a value of just under 3.5 log-cycles). We need this
value later.

__Q: Do all the data points lie to the RIGHT
of the unit-slope line?__

A1: Yes, the data is to the right of the line...

A2: No, quite a few data points lie to the other side of the line...

A3: I don't know. I forgot to write down C(min)...