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EX 1.1Example 1

FloSystem User Course

Well Model Building and Calibration

Naturally Flowing Oil Well

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EX 1.2Overview

Data Entry

Well Deviation Data

Well Completion Data

Reservoir Fluid Data

Reservoir Rock Data

Measured Data

Data Matching Inflow / Outflow curves

Pressure-Depth profiles

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EX 1.3Well Details

Mid-perf depth - 8500 ft MD

4.5 OD, 4 ID, 11.6 ppf tubing to 3460 ft MD

3.5 OD, 3 ID, 9.2 ppf tubing to 5000 ft MD

2.875 OD, 2.441 ID, 6.4 ppf tubing to 7000 ft MD

7 OD, 6.3 ID, 23 ppf casing to 8500 ft MD

Oil 38 API Water Gravity: 1.1

Gas Gravity: 0.82 GOR : 400 scf/stb

Water-cut: 17% Res. Press.: 3800 psia Pb : 1850 psia Res. Temp.: 187 oF

PI: 3.6 stb/day/psi Bo : 1.2 rb/stb

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EX 1.4Dataprep General

Select File - New

Select DataPrep - General

Report Labelling

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EX 1.5Datum

Double-click on Xmas Tree

Enter Datum details

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EX 1.6

Rotary Kelly Bushing

Wellhead Elevation

Mean Sea Level

Sea Bed

Datum

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EX 1.7Deviation Data

Select Dataprep - Deviatio n Data - Well Data

Insert three lines, enter MD, TVD pairs - edit last

row to 8500, 7500

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EX 1.8Well Components

Select Dataprep - Equipment Data - Well Data

Enter data (node depth is BOTTOM of component)

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EX 1.9Well Components

Select Con fig - PreferencesView Component name only

Try changing view from text to icons using View- Disp lay as TextorDisplay as icons

In Config-Preferences, view MD, componentdata, etc.

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EX 1.10Completion Editing

Go Back to Deviation Data

Highlight 7000 - Insert Row

Enter MD 6000 and TVD 5200 Note that a new node has been inserted in

Tubing 3

Double-click on the lower section of Tubing 3

Re-label as Tubing 3b. Call the upper partTubing 3a.

Select Con figure - Preferencesand include allthe options in the text display

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EX 1.11PVT Data Entry

Select Dataprep - Reservo ir Con tro l - FluidParameters

Enter

Oil Gravity 38 API

Gas Gravity 0.82

Water Gravity 1.1

GOR 400 scf/STB

Water Cut 17 %

Select Check:Pressure 3800 psi, Temp 187 oF

Note Glasos correlation results

Pb =1715 psi, Bo = 1.20129

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EX 1.12PVT Data Matching

Select Match, change temp to 187 oF, enter 1850psi beside temp and Calculate

Note Pb = 1715 psi. Press Best Fit Note new Pb = 1850 PSI

Select Form. Vol. Factor as Match Property

Change pressure to 3800 psi

Enter 1.20 as Bo beside 187 oF, 3800 psi field Calculate - Best Fitto tune Bo

Glasos correlation is now tuned for usethroughout the well model

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EX 1.13IPR Data Entry

Select Manual Entry model and Edit Layer

Enter layer pressure = 3800 psi, temp = 187 oF

and PI = 3.6 STB/day / psi Select Choo se IPRand Vogel, then Plot

Minimise graphing window

Select Norm . Pseudo Pressu reand Plot

Select Straight Lineand Plot

Note that all three IPRs are plotted on the samegraph

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EX 1.14IPR Data Entry (contd.)

Maximise graphing window

Double Click on Y axis, note that the Round optionis selected

Note the other options Click Edit , observe options of changing axes, titles,

activate the coordinates and add a description of thegraph.

You can save the graph configuration as a template(File - Save Temp late)and also print it. (File - Print )

Close the graphing window and select Vogel modelfor use in the rest of the exercise

Select OK until returned to the icon display

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EX 1.15Measured Data

Use Notepad to view the file EX1.RVP (ASCIIFile)

This file contains one line - 5900 2200 - the first

number is observed surface flowrate in STB andthe second is well flowing pressure at that rate -this is the measured data to which we will matchthe model

Return to WellFlo Select File - Load Measu red Data -

Flow rate versus Pressu re

Load EX1.RVP - note one pair of values reportedas read , it is possible to load multiple pairs.

Display on the Choo se IPRplot.

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EX 1.16Well Model Tuning

Select Analysis - Operat ing point

Select Edit Rates

Select Rate in lower left of screen / 1000 / 10,000 and 9

steps, select Filland OK

Tatm. = 60oF Pwh = 200 psia (Top node Xmas Tree)

Check Sensit iv i tyOff (both)

Set Correlat ionto Duns and Ros(std)

Select Calculateand on completion of calculationResults and Plot .

Selecting Measu red Data on then Plot to see theInf low /Outf lowplot

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EX 1.17Well Model Tuning

Note that the model represents a reasonablematch to observed data.

On Nodal Analysisscreen select Sensit iv i t ies

Select Flow Correlat ionas sensitivity 1 and edit (1) Duns and Ros (std); (2) Beggs and B r i ll (std)

(3) Hagedorn and Brown (std); (4) Orkizewski

Return to Nodal Analysis. Switch Sensit iv i ty1 on

and Calculate. On completion, select Results and Plot and A llValues for sensitivity 1 and Plot again

The four outflow curves are plotted with the IPR

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EX 1.18

Well Model Tuning

Zoom on the region of the plot where theintersections and observed data are.

Switching on Iterate To Exact Operating Poin twill give a more accurate operating point. Thisoption should always be used.

Note that Hagedorn & B rown(std)comesclosest to the observed data.

To get a better match, tune the correlation to themeasured data using the L- factor as asensitivity.

L modifies the computed pressure gradients.

An acceptable range for L is 0.9 to 1.1.

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EX 1.19

How should the productivity index be changedto obtain a match on the inflow curve?

What other reservoir parameter could be the

cause of the slight mismatch? What else could be at fault?

Well Model Tuning

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EX 1.20

Well Model Tuning

Return to the Fluid Parameterssection and re-tune the formation volume factor to 1.3

Repeat the calculation with the same sensitivity

values and note that the observed data nowplots closer to the Duns and Roscorrelationoutflow curve.

Return the Bo tuning to 1.2 and select theHagedorn and Brow n(std)correlation.

Switch off sensitivity and calculate and plot theinflow/outflow curve.

Note the well flowrate reported on the graph

Return to graphical editor.

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EX 1.21

Well Model TuningPressure vs Depth

Select File - Load Measured Data - Depth (MD)vs.Pressure (and Temp), & load EX1.DVP

Select Analysisand Pressure Dropand enter theoperating rate you just obtained

start node is Xmas Tree at 200 psia

solution node (end node) is Casing (mid-perfs)

Calculate and plot results as Pressure vs.

Measured Depth, including measured data Try Operat ing Poin tcalculation mode withIterate to exactswitched on. This willautomatically provide you with a pressure-depthplot at the appropriate operating rate.

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EX 1.22

Data MatchingPressure vs.Depth

Return to Pressure-Drop Calcu lat ion, switch onsensitivity 1 (flow correlations) and Calculate.

Now plot pressure versus depth with A ll valuesset in the sensitivity option.

The Hagedorn and Brown (std) correlation givesthe best match to the whole flowing gradientsurvey.

Switch off Sensitivity 1. Reverse the Pressure-Dropcalculation with start node as casing (whatpressure?), and solution node as Xmas tree.

Compare the computed and measured data,

especially the THP.

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EX 1.23

Summary

A naturally flowing oil well was used todemonstrate model building and calibration

The same procedures can be applied to oil wellson artificial lift (gas-lift or ESP), gas andcondensate producers and gas or waterinjectors.