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In this lesson you will perform a Fetkovich Type Curve analysis and Type Curve Match.

Using Fetkovich Type Curve Analysis

1. Clear any previously applied filter. Expand the Well List node in the Filter pane and select Prod_Wells98.txt.

3. Select BLUE_5:Sc_0 and open a Forecast window.

4. Add a new case named Case3 to the project.

5. Select Edit > Scenario, and the Current Scenario dialog displays.

6. Associate the following on the Flow Model tabbed page.

NOTE: When you select Fetkovich Type Curve from the Solution list, the other parameters in the Model Description section of the dialog are grayed out.

If you have dynamic (data loaded into a table, e.g., monthly) pressure data and want to use them, associate the variable at the Flowing Pressure list; otherwise you can enter (static) pressure values in the Pressure group box.

Fetkovich analysis uses PVT data in its algorithms. The default PVT properties for this project contain a value for rock compressibility of zero. This must be changed (using Database >

PVT/Edit…) to a more appropriate value; otherwise type curve matches fail. We suggest a value of 0.000003 psi-1.

Schlumberger Public 7. Select the Parameters tab and accept the default parameters

to start history matching.

8. Click OK. The graph displays. (You will have to add the header, resize the graph, legend to get the desired output.)

Schlumberger Public 9. Reinitialize your data by right-clicking on the graph. A shortcut

menu displays. Select Reinitialize.

10. Position your cursor at your desired data point and click to highlight the point. Only the Time (x coordinate) value is important here.

11. Right-click and select Reinitialize from the shortcut menu.

12. Click OK. Your data has been reinitialized.

NOTE: OFM may display a dialog with a Reinitialize Data Tip, as shown here.

TIP: You can also adjust the data fitted curve (Dark Green) by positioning the cursor over that curve. When a hand appears, click the curve and drag it to your desired location; then release the mouse.

Schlumberger Public 13. Position your cursor over the real curve until the cursor

changes to a four-headed arrow, drag it and move it

(remember the “initial” point of the decline period) closer to the displayed type curves.

14. Select Tools > Typecurve Match. OFM runs the matching algorithm and returns the following:

15. Select Edit > Scenario.

16. Select the Parameters tab. Observe that after running the matching algorithm, OFM returns the calculated results for the b value and Permeability, Skin factor, Drainage area (if you are performing both early- and late-time analysis).

17. Select the Flow Model tab and clear the Late-Time Only checkbox (just an exercise).

18. Close the dialog and rerun the matching algorithm. The program returns a set of parameters.

19. Clear b value and Permeability text boxes, check Skin factor and enter 45 in the Estimates field, check Drainage Area and enter 300 in the Estimates field.

20. Click OK.

NOTE: You may get a failure message as the result of this operation. In this case, go back to the Scenario >

Parameters tab, adjust the values of your matching parameters, and rerun the Typecurve Match command. If you have any questions, feel free to seek help from your instructor.

Schlumberger Public 21. Select Tools > Typecurve Match. The new result returns.

22. Select Edit > Scenario.

23. Select the Parameters tab.

Based on the returned skin factor, you would have a good idea of what the next estimate Skin factor should be.

Remember that you can vary all four parameters in your matching criteria.

24. Enter the values provided in the table below.

Permeability 30 (md)

Skin Factor 60

Drainage area 700 (acre)

b value 0.3

25. Click OK. If required, re-initialize your data.

26. Select Tools > Typecurve Matching. The graph displays and the results reported in the Legend box are different.

Schlumberger Public 27. Edit the Scenario. Select the Parameters tab and examine

the return values of the matching parameters.

Keep repeating the operation by supplying better estimates, running history match, until you get a good match. Do not forget, these parameters are really important. By changing the values of Wellbore Radius, Net Pay, and Porosity, the

magnitude of your matching parameters is strongly affected.

For example, you can run the matching algorithm with this set of parameters:

28. Sometimes you will get a matching failure message. One of the reasons could be that it does not converge after a certain number of iterations. Click on Matching Calculation Settings and this window appears:

TIP: You can select to match on production rate,

incremental production, or cumulative production. You can also specify the number of iterations and the

Schlumberger Public 29. After running the matching algorithm, OFM returns the

calculated match parameters (which normally are different than the estimates you entered). Click Update to use the Results as Estimates for the next run, or click Revert for the opposite.

Remember, the settings on your Forecast tab are of your default setting (Current Scenario).

30. Select Tools > Forecast. OFM runs the forecast and displays the forecast results.

31. Select Edit >Scenario.

32. Check the Late-Time Only box. This action disables the pressure information. Click OK.

33. Move the real curve closer to the type curves, and then select Tools > Typecurve Match. The result displays.

Schlumberger Public 34. Select Edit > Scenario and select the Parameters tab. You

can see in Late Time analysis, the only matching parameter used is the b value.

After running Fetkovich Type Curve analysis (with and without the Late Time Only option), your matching parameters can be used back in Empirical Solution method to get a better decline estimation.

Question

Examine the results in Step 30. What conclusion can you make?

Review Questions

• When is it most appropriate to use Fetkovich Type Curve analysis?

• In a type curve match, which reservoir parameter settings significantly affect your matching parameters?

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Summary

In this module you:

• used Fetkovich TCA

• performed Type Curve Match.

In the next module, you will learn how to forecast using Analytical Transient Analysis.

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NOTES

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NOTES

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Module 5 Analytical Transient