Analysis-data is usually prepared from ASCII (text) files provided by a service company that hold the pressure and rate data recorded during a test. Preparation of Analysis-Data from an ASCII-file begins by using the option "Read ASCII-file..." under the "ASCIIprep" pull-down menu. This option will display a series of steps to read the data from the file into a set of Gauge-Data which can be stored, added to, or manipulated using graphics functions. Gauge-Data can also accumulate the data from several ASCII-files to create a single entity to hold the data for a test.
Gauge-Data is in a format that can be scanned and randomly accessed by PIE so the flow-periods and pressure points to be used for the analysis can be selected as desired. Gauge-Data can also be saved in a PIE-file, and multiple sets of Gauge-Data can be identified and managed using the Gauge Manager.
Gauge-Data can be read from a plain text file using a "read-wizard" which is very similar to importing text into a spreadsheet. Select the option "Read File into Gauge" under the "ASCIIprep" pull-down menu. This will display the system interface to browse the folders and select a file. Once a file is selected, the wizard will go through a series of steps which define how to "parse" lines in the file, identify each column of data in the file, sets a conversion factor, and then reads the data into PIE. This process can be repeated as many times as desired to accumulate multiple sources of data into a single set of gauge-data in PIE.
TIP: you can also select an ASCII text-file using the option "Open Test File..." under the "File" pull-down menu. When the system interface for selecting a file appears, make sure the option "files of type" is set to "Text files", "TPR files", or "All Files" so PIE knows raw-data is to be processed.
Gauge-Data can also be transferred to PIE from a spreadsheet using a simple copy and paste operation. View the raw data in your favourite word-processor or spreadsheet program, select the data, copy it, switch to PIE, and paste. It's just that easy...
NOTE: Microsoft EXCEL™ allows discrete columns of a spreadsheet to be selected and copied to the clipboard using a "control-select" keyboard-mouse operation. However, EXCEL will place ALL of the data that lies between the selected columns on the clipboard along with the selected columns. This is not a problem, but a different set of data will be seen in PIE than was selected in EXCEL. This behaviour is a fault in EXCEL when it prepares text data on the system clipboard.
Gauge-Data can be edited with the "ZAP-RG" graphics function to remove data. This allows any data that is not relevant to the test sequence to be removed from the gauge-data. The "ZAP-RG" function defines a box around a section of the data, and then allows different delete options to be applied to the data inside that box.
Gauge-Data can include both rate and pressure data, and can be used to define the rate-history for the test. Just read or paste the raw data into the gauge-data specifying the data column to be "rates" rather than "pressures". This can be repeated as many times as desired to accumulate rate information from various sources.
Once the gauge-data has been set-up, the rate-history to use for the analysis can then be defined using various methods. The option "Add Flow-periods to the test" under the ASCIIprep pull-down menu allow each "click" on the plot to be translated into a flow-period in the rate-history. If there is no rate information at the selected point, then PIE will prompt for a rate-value to be entered directly.
Once the rate-history has been defined, the pressure data to use for the analysis can be selected. The rate-history plus selected pressure data forms the Analysis-Data which is used to prepare the analysis plots and derive the analysis results.
The Gauge-Data and Analysis-Data can be saved to a PIE-file just by selecting the "Save" option under the FILE pull-down menu. This will save both the gauge-data and analysis-data.
If you wish, a PIE-file can store multiple sets of gauge-data without limit. This is handy for accumulating all the raw-data for a well in a single PIE-file. The gauge-data manager is accessed from the "Load/Save/Delete Gauge" option under the ASCIIprep pull-down menu.
TIP: The gauge-data stored in PIE can be exported into a text-file using the options "Save Pressures to a Text file" or "Save Rates to a Text file" under the ASCIIprep "Advanced Options..." menu. These options allow a PIE-file to be used as a central repository of raw-data which can then be recovered back to a text format if necessary.
Similar to the gauge-data, a PIE-file can store multiple sets of analysis-data without limit. This allows the data for independent analyses to be identified and accumulated in a single PIE-file. The option "Analysis-Data Manager" under the EDIT pull-down menu is used to access this manager.
NOTE: The independent gauge and analysis data entities allow multiple sets of analysis data to be created from a single set of gauge-data or vice-versa. This is useful when trying different test set-ups (e.g. multi-phase verses single-phase), or if the gauge-data contains multiple tests (e.g. before and after re-perforating).
A well-test analysis needs various constants to calculate results, and other settings to control how the results are presented and how the calculations are performed.
The initial settings for the analysis constants can be entered in a single table using the option "Static-Data" under the EDIT pull-down menu. For gas-well tests, the PVT data also needs to be set-up using the option "Edit PVT Data" also under the EDIT pull-down menu.
The units system can be adjusted with the "Edit Units" option under the EDIT pull-down menu. This option is used to select either oilfield units, SI metric units, or custom units you control. Different units system can be applied to input data, graphical display, and printed output.
The "Period for Analysis" (PFA) controls which rate and pressure data are used for the analysis. The PFA is selected from the "Period for Analysis" option under the "MAIN" pull-down menu. The ability to change the PFA allows several tests to be analysed from a single set of Analysis-Data.
The PFA is selected as a range of consecutive flow-periods from the complete rate-history of the test. The pressure data in the last flow-period of the PFA is used to prepare the various analysis plots. Any sequence of flow-periods can be selected as the PFA subject to the following restrictions:
- there must be pressure data in the last flow-period
- there must be a pressure value at the start of the last flow-period of the PFA.
- if only a single flow-period is selected as the PFA, the rate during that flow-period cannot be zero.
The text-book well-test analysis methods are called the basic diagnostic results in PIE. Once the analysis-data, constants, and period-for-analysis have been defined, the basic analysis results can be derived using any of the standard well-test plots.
Analysis plots are displayed from the PLOTS pull-down menu. A button-bar containing various graphics functions is displayed with a plot. These graphics functions allow a line to be drawn through the characteristic portions of the data in order to compute results. The basic results of permeability, skin, and reservoir pressure are estimated using either the derivative or superposition plots.
Comparing analysis plots for different sets of data is a basic analysis method that helps identify important changes in well behaviour. The Derivative plot is the most common plot to use for comparison. The "Copy" and "Paste" options under the EDIT pull-down menu allow a "plot overlay" to be constructed from two PIE plots. To construct a plot overlay, first display a plot, then select the "Copy" option, display a second plot, and finally select the "Paste" option to create the overlay. To remove a plot overlay, right-click on the plot and select the option "Remove Overlay".
Note that the two plots can be for different sets of data, or even from different PIE-files. There is also no restriction on how many times the copy and paste operation are performed.
There are two main 'managers' in PIE that are used for creating reports and saving an analysis. The first is the Result Manager which allows the results of an analysis to be saved to and re-loaded from a PIE-file. The second is the Plot Manager which allows complete analysis plots to be saved to a PIE-file and then manipulated for presentation in a report or to enhance an analysis
As the analysis proceeds, a particular analysis plot can be saved to the PIE-file by doing a right-click on the plot and selecting the "Save Plot" option. Saved plots can be reviewed later from the Plot Manager under the "Report" option of the MAIN pull-down menu.
Any plot can be copied to another application by using the "Copy" option under the EDIT pull-down menu, and then using the "Paste" option in the other application.
This "copy and paste" operation can also be used within PIE itself to create an overlay of two plots.