2. Ajuste Del Modelo de Pozo

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EX 2.2Sensitivity Modelling

This is based on the data used in Example 1, with

sensitivities set up to model well performance as water-cut

increases and reservoir pressure declines.


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Select File - Openand load EXAMPL2.WFL

Select Analysis - Operat ing Po int - Sensi t iv i ty

Review Sensitivity Values selected Water Cut Values = 17%, 40% and 70%

Reservoir Pressures = 3800 psia, 3500 psia & 3000psia


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Review other sensitivity groups

sensitivities available depend on the data input to the model

Calculateto perform the Sensitivity Analysis.

10 rates x 3 x 3 = 90 calculations. Max = 21 rates x10x10 = 2100

Plot as Inf low/Outf low

Layer pressu re= All values Water Cut= All Values

Note that one sensitivity set is labelled no operating

point. Identify which sensitivity values the condition corresponds

to and plot it individually as an Inf low - Outf lowplot.


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Note generally that any one sensitivity value can be plottedagainst any other.

On the Plot Opt ion sdialog box select Performance

Analysis. You can plot Operat ing RateorPressureagainstone sensitivity with the other sensitivity as the curve family.

Plot operat ing rateagainst water cu tfor all three layerpressures.

Note that on the Plot Opt ion sscreen almost any

combination can be used to set up the desired presentationin the Performance Analysis. Try other combinations.


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Investigate the minimum layer pressure for stableproduction at 40% water cut.

What would this well produce at a layer pressure of 3800psia with a zero water cut?


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EX 2.7Plots Vs Depth

Standard plots show pressure and temperature Vs depth.

Rerun your operating point analysis with Iterate to exactswitched on, and inspect the pressure-depth plots.

Select Con f ig - Select Plot Axesto display other variablesVs. depth.

Limited to two parameters on any run

Must be defined before calculating

Try Pressure gradients, Flow regimes, in si tu l iquid

ho ldup , etc. For more variables and more flexibility, use

ANALYSIS.LOG file (discussed later). Next


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Try with new axes as Erosional velocity and in-situ liquidvelocity or mixture velocity.

Determine what problem can the completion has and atwhat depth.

Make a sensitivity to the diameter of the tubing withpossible problems to check if its recommendablechange the diameter at this depth.

Make a sensitivity to P layer and check if this can solve theproblem at future.

Solids can increase the problem.


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Try changing plot axes to superficial gas velocity andTurner critical velocity.

Check running operating point, plot pressure/depth anddetermine flow stability. (one of the stability criteria).

Try again changing axes to in situ liquid hold up andmixture density for instance.


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EX 2.11

Reviewing previousanalyses

Return to the graphical interface and select View Resu ltsfrom the Analysismenu.

Select Ex2v36c.CLC and Open

Then Plotto review the results of a more detailed analysis.

Ex2bv36c.CLC is an even more detailed analysis

After opening a .CLC file, it is possible to create a reportfor this data.


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EX 2.12Reporting

Subjects covered:

Export to Tab-separated files - WELLFLO.RPT

Reporting in Write/WordPad. Copying graphs to Word Processors.

Data in Analysis. log.

Data in WellFlo. log.


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EX 2.13Reporting in Write

Load EXAMPL2.WFL and View Results - OpenEx2v36c.CLC

UnderCon f igu re - Preferencesselect Tabbed Text Format

Go to Analysis/View Resu lts - Repo rt

Scan through the file and review.

Go back to Con f igu re - Preferences andselect RTF (defaul t)

Go to Analysis/View Resu lts - Repo rtagain and check the

improved report formatting in WordPad.

You can call up your own report browser (see manual).


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EX 2.14Reporting

The Macro fo rmatoption underConf ig ure Preferencesinserts markers into the report that can be used by a macroto prepare the desired format (tabbing, pagination, boldheadings, etc). You might need this if your favourite word

processor cannot handle rich text format (RTF). Each section is numbered and labelled with three asterisks

on the following line. These can be used to find theappropriate section and enter page breaks, select textformat and change styles.

This has been superseded by the RTFoption, which shouldbe compatible with most word processors.


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EX 2.15

Reporting -Pasting Plots

Bring a report up on screen (open WELLFLO.RPT). Go backto WellFlo without closing down Wordpad (Notepad) *

Plot Performance Analysis. If desired, the plot can beprinted directly from here (File - Prin t), or pasted in the

report.

Alt+PrintScreenallows you to copy the graph to theClipBoard. From here, it can be pasted directly into thereport, or into a graphics program (such as PaintShop Pro,PaintBrush)* for editing, and then copied into the report.

Once the graph is ready, insert it into the report using Edit -Paste (or Ctrl+V)

* Alt+Tabis a useful shortcut to jump betweenapplications


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EX 2.16Reporting

Close WELLFLO.RPT in WordPad (or NotePad)

Go to Program Manager and load Excel or otherspreadsheet package.

Open WELLFLO.RPT in spreadsheet (text file). Note that theTabbed Format is Excel compatible, but the rtf is not.

Review File.

Try graphing some of the data.

Pressure depth plots etc.


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EX 2.17Detailed Reporting

Return to WellFlo.

Select Conf ig ure - Preferences.

Switch on the options to output ANALYSIS.LOG and

WELLFLO.LOG Normally switched off as these files are written as the program runs

and slow down execution.

WELLFLO.LOG includes similar information toWELLFLO.RPT but is not formatted and has a time stamp.

Useful for identifying problems. ANALYSIS.LOG provides a detailed listing of: phase

densities, viscosities, flow regimes, hold ups, erosionalvelocity, unloading velocity, etc. Open this file in Excel andinspect.


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EX 2.18Export To Simulator

Load EXAMPL2.WFL again and select Analysis - Export toSimulato r - VFP File For Ec l ips e - Sing le Well

Select File - DOS Form at(note UNIX option)

Select Units - Oil f ield- note that this module uses unitsystems consistent with the reservoir simulators for whichthe file will be built.

Select Flowrates:

From 1000 to 10000 with 9 steps

Select Gas Ratios: Leave one value at 0.4 - note units


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EX 2.19Export to Simulator

Select Water Cut:

Set the first three values to 0.17, 0.2 and 0.4 (decimal units)

Select Pressures:

Set three values to 100 psia, 150 psia and 200 psia at tubinghead

Select Create Fileand export to EXAMPL2.VFP.

Switch to NotePad and load the file just created.

Note that the file contains the keywords and is correctly laidout to be pasted directly into the control file for the

Reservoir Simulator.


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EX 2.21Summary

Sensitivity modelling and reporting have been examined fora naturally flowing well.

The various graphing and output options including

exporting data to reservoir simulators was reviewed. These features are fundamentals of WellFlo and can be

applied to oil, gas, condensate, ESP and gas-lifted wells fora wide range of applications.

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2. Ajuste Del Modelo de Pozo