Example 1
EX 1.1
Well Model Building and Calibration in Wellflo 2010 Naturally Flowing Oil Well
Introduction •
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EX 1.2
This example will help you to learn how to build a simple, one layer, naturally flowing oil well model Building well model includes the following steps: 1.
Step 1: Da Data Entry Entering the necessary reservoir and well data
2.
Step 2: Model Tuning Tuning your base model to match the observed data
Data Entry Step 1 •
EX 1.3
To design a well model you need to enter these sets of data: –
Reservoir data: » Reservoir layer properties » Reservoir fluid properties
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Well data: » Deviation data » Well completion data
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Surface facilities data: » Data related to the facilities above wellhead such as riser, choke, separator...
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Observed data: » Pressure-Depth profiles » Temperature-Depth profile » Measured production rate or bottom hole flowing pressure
Step 1
Summary of Well and Reservoir Data •
1.
2.
EX 1.4
These are the summary of different sets of data that you will use during this exercise. Well data: –
Casing: 1- 7” OD, 6.4”
ID, 23 ppf casing to 8500 ft MD
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Tubings: 1- 4.5”
OD, 4”
ID, 13 ppf Tubing to 3460 ft MD
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2- 3.5”
OD, 3”
ID, 11 ppf Tubing to 5000 ft MD
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4- 2.875” OD, 2.4” ID, 9 ppf Tubing to 7000 ft MD
Reservoir data: –
Oil 38 API
Water Gravity: 1.1
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Gas Gravity: 0.82
GOR : 400 scf/stb
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Water-cut: 17%
Res. Press.: 3800 psia
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Pb : 1850 psia
Res. Temp.: 187 oF
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PI: 3.6 stb/day/psi
Bo : 1.2 rb/stb
Step 1
Data Entry in WellFlo 2010 •
1.
The data will be entered in the “WellFlo 2010” in following steps: Initialization: –
General data
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Well and flow type
2.
Flow Correlation
3.
Reference Depths
4.
Fluid parameters
5.
Reservoir
6.
Wellbore
7.
8
EX 1.5
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Deviation data
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Equipment
Surface data –
Terrain data
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Surface equipment
Temperature model
1- Initialization: General data Step 1 •
EX 1.6
In this step enter the general data related to your project.
1. In configuration panel click on “file” and select “New” then click on “General Data” .
2. Remember in each step after you entered the data click on “Apply”.
1- Initialization: Well and flow type Step 1 •
You need to define the Well and flow type: –
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EX 1.7
Vertical Producer, Black Oil, no Artificial Lift
Click on “Well and Flow type”
2- Flow correlation Step 1 •
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EX 1.8
This menu used to select the correlation to measure the pressure drop across completion resulted from friction . Click on “Flow Correlation” : leave it by default
3- Reference Depths Step 1 •
EX 1.9
In this section you should define your reference point for depth measurement: In this example R o t a r y K e l l y B u s h i n g (RKB) is the reference point.
Rotary Kelly Bushing Wellhead Elevation Mean Sea Level
Sea Bed
3- Reference Depths Step 1 •
EX 1.10
Click on “Reference Depths” : Enter details as below
4- Fluid parameters Data entry Step 1 •
EX 1.11
In this section PVT data should be entered.
1. Click on “Fluid Parameters” : Enter Properties as below
2. Click on “Calculate”
4- Fluid parameters Data matching Step 1 •
Lab test indicated that Pb=1850psia, therefore the correlation should be tuned.
1. Click on “Tune correlation to PVT data” 2. Right click on “Fluid Model” and select “Add Black Oil Experiment data” . 3. Change temperature to 187oF, Pressure (below) to 3800psia, and Saturation Pressure to 1850 psi, and “Match ” then “ Accept” •
Now Pb matched to the lab test: Pb=1850 psia.
EX 1.12
5- Reservoir Step 1 •
EX 1.13
Reservoir properties and the parameters of desired IPR curve should be entered.
1. Select “Reservoir” then “Manual” : Enter the properties as below in “General” tab:
5- Reservoir Step 1 2. •
3.
EX 1.14
Click on “IPR” tab to see IPR curve. The observed surface flowrate once was 5900 STB while the well flowing pressure at that rate 2200 psia - this is the measured data to which we will match the model. On the IPR plot press “Import External Data” : Enter the data, then click “OK”.
6- Deviation Data Step 1 •
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EX 1.15
Up to now well type has been defined and reservoir rock and fluid properties has been entered. Wellbore data including Deviation and Equipment data should be entered in the following sections. Click on “Deviation” in Wellbore section: Insert three lines, enter “ MD, TVD” pairs - edit last row to 8500, 7500
7- Equipment Step 1 •
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EX 1.16
Well completion was described in Slide 2 Select “Equipment” then “Tubing” tab: enter data as below. After that select “Casing”: enter associated data
8- Dashboard Step 1 •
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EX 1.17
Data entry has been finished and the base model is designed. This section will show you a schematic of your production system. Click on “Dashboard” .
Model Tuning Step 2 •
EX 1.18
In this step the designed well model should be tuned to match the measured data. This includes 3 steps: 1.
Finding the operating condition of the model which means determining operating rate, operating bottomhole flowing pressure and pressure or temperature profile versus depths.
2.
Comparing the results of the model with the provided measured data.
3.
Running proper sensitivity analysis to select and tune the desired parameters for example flow correlation.
Operating Condition Step 2
EX 1.19
1.
Select “Analysis” panel. Then “Operating Condition”.
2.
Set the “rate” from 1000 to 10000 in 9 steps, then click “Fill” and “Apply”.
3.
Enter Pwh=200 psia then “apply”, and click “Calculate”.
Matching model with Measured Data Step 2 •
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EX 1.20
The well model does not show the results observed in reality because its pressure correlation is not correct. It is corrected by choosing the correct correlation and later tuning it trying to match the measured data: pressure vs. depth (when choosing the correlation) and operating rate&pressure (for tuning the chosen correlation).
Tuning the Model to Match the Measured Data EX 1.21
Step 2
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In “Analysis” tab select “Wellbore Equipment Profile” . Select “Edit or Export External Data” . Add a row and copy-paste the data from Example1.xls. Note the model represent reasonable match with observed data.
Tuning the Model to Match the Measured Data EX 1.22
Step 2
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In “Analysis – Operating Conditions” tab check “Pressure Drop” and enter only on e rate =5900stb – t o e n s u r e t h a t w e c o m p a r e p r ed i c t e d pressure profile vs. the observed on e for the same rate
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The next step is running sensitivity analysis on different Flow correlations to select the best one.
1. In “ Analysis” tab select “Sensitivities”. Create “Well and riser Flow correlation” as “sensitivity 1” : –
(1) Duns and rus(Std); (2) Beggs and Brill (Std)
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(3) Hagedorn and Brown (Std); (4) Orkizewski
2. “Apply” then “calculate”.
Tuning the Model to Match the Measured Data EX 1.23
Step 2
3. Click on “Include in Plot”. Select all correlation and then select “Plot Selected”.
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Note that the H ag e d o r n a n d B r o w n (S t d ) comes closest to the observed data. Therefore put it as your Flow Correlation in Configuration panel.
Tuning the Model to Match the Measured Data EX 1.24
Step 2
4. Come back to “Operating Conditions” . Select “Flow curves”. Import the operating rate and pressure.
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The measured operating rate and pressure can be used to tune the Flow correlation. In “WellFlo 2010” Flow correlation can be tuned by changing “L- Factor”. L-Factor is a correction factor that modifies the computed pressure gradient and it has an acceptable range between 0.9 and 1.1.
Matching model with Measured Data Step 2 5. Go to “Sensitivities”. Create new “Sensivity 2” for “Well And riser factor”. Then “Calculate” and L - plot the results. 6. Select the best L-Factor and enter it in “Flow Correlation” in “configuration” panel. •
You have now the tuned well model that can be used for further analysis.
EX 1.25
Qestions •
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EX 1.26
How should the productivity index be changed to 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?
Useful Tips
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EX 1.27
“Copy to clipboard” allows you to copy (and later to paste) the graph to the ClipBoard. From here, it can be pasted directly into a report. Select data in a spreadsheet below a graph and copy-paste them below the graph into your report.
Summary •
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EX 1.28
A naturally flowing oil well was used to demonstrate model building and calibration The same procedures can be applied to oil wells on artificial lift (gas-lift or ESP), gas and condensate producers and gas or water injectors.
