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LedaFlow® Tutorial 2014
LedaFlow® Tutorial
Study of severe slugging effects in a
Pipeline/Riser geometry
LedaFlow® Tutorial 2014
Table of contents
Sommaire Introduction ............................................................................................................................................. 1
Create a database .................................................................................................................................... 2
Create a case ........................................................................................................................................... 3
Set PVT option ......................................................................................................................................... 6
Set heat transfer option .......................................................................................................................... 9
Define the pipe wall properties ............................................................................................................. 10
Set pipe geometry ................................................................................................................................. 13
Configure mesh ..................................................................................................................................... 15
Set boundary conditions ....................................................................................................................... 17
Set numerical parameters ..................................................................................................................... 18
Run the case .......................................................................................................................................... 20
Plot and export the results .................................................................................................................... 21
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Introduction This tutorial has been designed to study the severe slugging effects found in a simple geometry, using water and air at atmospheric pressure. The document teaches step by step the basic features of LedaFlow: from creating a database and a new case to analysing the obtained results. Geometry This tutorial will be based on a previous report written by J.Fabre et al for the Society of Petroleum Engineers, published in 1987 (SPE 16846).. The following figure represents the geometry of the pipeline that will be used during this exercise.
Device characteristics
Pipe diameter 53mm in the entire system
Pipe geometry Pipeline of 25m riser of 13.5 m 50 cm radius bend
Pipe walls 5 mm of steel 5 mm of an insulation material 5 mm of an isolated coating
Ambient temperature 20 ºC
Inlet conditions Gas mass flow rate: 0.000533 kg/s Water mass flow rate: 0.280167 kg/s
Outlet conditions 1 bar 20 ºC
0
2
4
6
8
10
12
14
0 5 10 15 20 25
Z -
Pip
e h
eig
ht
(m)
X - Pipe length (m)
Pipeline/Riser geometry
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Create a database
LedaFlow uses a MySQL version 5.1 as a database service. The user has the possibility to create
several databases inside MySQL to organise data. The database management tool allows the user to
manage all the databases and their contents.
Go to the “Tools” menu
Click on “Database management”
Click on the “Databases” tab
Create a new database by clicking on the “Add new” icon
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Name the database “severeslugging”
Click on “Close” once the database has been created. Your case will be saved in this
database.
Note: LedaFlow saves automatically all changes and results. You do not need to save it manually.
Create a case
Create a new folder called “SevereSlugging” in the Case Browser:
Right-click on the default folder “Project” and select “Rename”
Enter the name “SevereSlugging” and click OK
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Create a default case
Right-click on the folder “SevereSlugging” and select “New case”
Select “Leda 1D - 2phases”
Enter the name “SevereSlugging Case” and click OK
A default 2-phase case has been created.
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Rename the pipes and nodes:
Right click on the pipe and select “Rename”
Rename pipe from “Pipe 1” to “Flowline”
Similarly rename “Node 1” to “Manifold” and “Node 2” to “Outlet”
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Set PVT option For this exercise, the user must set the thermodynamics options in order to run the calculation because we use a water-air mixture. The user could you use a specific PVT table or introduce the thermodynamic variables as constants among other options. In this tutorial the above-mentioned case will be explained.
Open the “Case setting” window
The following window appears.
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The first case is using the PVT table.
Load a PVT table
Click on the green plus sign under PVT Library
Click on the folder icon and search for the file “PVT.inp”
Name the table “PVT”
The other option is set the thermodynamic variables as constants.
Click on the green plus sign under PVT Library
Click on “Type” and select constant
Introduce the values manually.
Name the table “PVT”
Comment [AV1]: Tambien agregar nuestro caso, que es cuando metemos los valores manuelmente.
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Change the PVT object assigned to “Flowline”
Double-click on “Flowline” in PVT selection
Select “PVT” from the drop-down menu
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Set heat transfer option LedaFlow includes several options for heat transfer modelling: U Value, walls and dynamic walls. According to the option selected, the user will have to set up the wall properties.
Select the “Model options” tab in the “Case settings” window Select the option “Yes” for the “Temperature calculations” options. This activates the energy
equation in LedaFlow Select “Walls (dynamic)” as the “Wall heat transfer” option. This will instruct LedaFlow to
account for heat storage in the pipe walls
The following window appears
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Define the pipe wall properties
Define the pipe wall properties by clicking on the “Walls library” icon
Create new materials in the “Material option”
Add a new material by clicking on . Give the new material the name “Isolated”
Change properties of all materials
Isolated Insulation Steel
Density (kg/m3) 1300 500 1300
Conductivity (W/m.K) 0.2 0.03 0.16
Heat capacity (J/kg.K) 1500 1000 1500
Click on the “Walls” option
Add a new wall by clicking on close to “Wall1” Name the wall “FlowlineWall”
Comment [AV2]: Actualizar Procedimiento
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Under “Wall layers” option, click twice on to add two new layers Select the material “Steel” for the first layer, “Insulation” for the second one and “Isolated”
for the last one Set a thickness of 5 mm for each layer
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Click on “Save All”
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Set pipe geometry
Set the geometry for the pipe
Click on the “Pipe Properties” located in the main toolbar LedaFlow opens the following window, where you can edit the pipeline geometry and properties.
Open the Excel file that contains the geometry of the pipeline for this case
Copy the content of the file and paste it in the “Pipe Properties” window
Under the “Walls” column, double-click on “Wall1” and change the assigned wall to “FlowlineWall”. Do so for all geometry points to have the same wall all over.
Once the geometry is set, click on “Ok”. The following message appears
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The aim of this message is to warn the user that any changes on the geometry will affect the
mesh and the simulation results. Make sure that your geometry is well defined before
running the case
Click on “Yes” to continue
The geometry can be seen under LedaFlow
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Configure mesh The mesh is the discretization of the geometry for numerical computation.
Set the mesh for the pipe by clicking on the “Edit mesh in construction” icon
Click on the “Lock Geom points” button
Choose the “Uniform Method” under the Grid constructor case
Set the approximate number of cells to 210
Click on “Run”
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The following graph shows the geometry, the meshing and the L-Ratio of the S-Riser system
If you change the geometry in the “Pipe Properties Window”, you will have to update the meshing to continue What is the LENGTH RATIO? It is the ratio between the length of two consecutive cells and it is really important to keep it lower than 2 to run the calculation. Otherwise, LedaFlow will send a warning message. In any case, start the simulation with a fine mesh, like the one you have just created, and then try to simplify it. However, it is not advisable to have long cell lengths near the base of the riser and within the catenary. The idea is to be able to account for the filling and emptying of the base of the pipe, and if cells are too long, this effect may not be observed correctly.
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Set boundary conditions LedaFlow can handle mass-pressure and pressure-pressure boundary. The split can be either calculated automatically by flashing the fluid at the inlet or set through the volume or mass fractions of each phase
Set the inlet Gas
Right click on the inlet node
Click on “Properties”
Choose No for the “flash inflow” option Set the following characteristics for the inlet
Time (s) 0
Ft (kg/s) 0.2807
mg (-) 0.0019
ml (-) 0.9981
Temperature (°C) 20
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Set the outlet
• Right click on the outlet node • Click on “Properties”
Set the following characteristics for the outlet
Set numerical parameters
LedaFlow is using a dynamic time step which means the size of the time step depends on the grid and
the velocities through the CFL number.
The numerical settings are defined by: the maximum time step, the CFL number, the sample rate and
the time to advance the solution.
Click on the “Numerical settings” tab in the “Case settings” window
Set the following parameters
Simulation time (s) 1000
Sample time (s) 1
CFL 0.8
Dtmax 0.05
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LedaFlow® Tutorial 2014
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Run the case
Initialise your case
You can see the progress in the bottom bar:
Run your case
Once LedaFlow has finished simulating the case, the progress bar will be complete. If you go to the
“Output” tab, under the Status window, you can see the errors encountered (if any) and a review of
the simulation numerical results.
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Plot and export the results
You can visualise the terrain slugging effect by plotting the pressure as a function of time for the lowest point of the pipe. This point is the most interesting one, because it is where the liquid accumulates and does not let the gas go through.
To create a plot, click on the “Create a new plot” icon on the toolbar.
There are several plotting possibilities.
Select “Trend” from the “Plot Type” drop-down menu
Make sure that “Flowline” is selected under the “Plot Object” list
Under the “Templates” tab, ungroup “PT and phase mass flowrates” by clicking on the [+] sign
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Select “Pressure” to plot pressure evolution with time for this pipe
You can also choose “Pressure” from the “Select Variables” tab.
Once you click “Ok”, a new window will be opened where you will see the simulation results. By default, LedaFlow plots the trend of the first mesh cell. You will need to instruct LedaFlow to show you the results for the lowest point of the pipe.
To do so, click on the “Edit Position” icon on the toolbar located on the up-left corner of the new window.
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In the new window that appears, drag the position bar to reach the bottom of the pipe, at 25.1277 m (cell number 148).
Click on “Ok”. LedaFlow will plot the pressure trend on this point. To export the results to a .csv format, click con the “Export data to .csv file” icon on the toolbar.
This will allow you to work on the results in other software, like Excel.
Congratulations, you have finished the tutorial. Analyse the results of the simulation in terms of
pressure amplitudes and slugging periods.
What should be the amplitude expected?
What parameter controls the slugging periods?
Verify that all boundary conditions are respected (mass flow rates, temperatures, etc.)
Reproduce the same simulation with the following boundary conditions
Sup. Velocity at Std Conditions (m/s)
Case 1 Case 2
Gas 0.45 2.24
Water 0.127 0.127
Compare simulated results with experimental data provided by the paper
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Annexe
Example of a geometrie for this tutorial
X [m] Y
[m] Z
[m] Diameter
[mm] Roughness
[mm] Tout [C]
Hout [W/m2-K] Walls[]
0 0 0,25 53 2 6,85 1000 Wall1
5 0 0,2 53 2 6,85 1000 Wall1
10 0 0,15 53 2 6,85 1000 Wall1
15 0 0,1 53 2 6,85 1000 Wall1
20 0 0,05 53 2 6,85 1000 Wall1
22 0 0,03 53 2 6,85 1000 Wall1
24,1 0 9 53 2 6,85 1000 Wall1
24,3 0 7 53 2 6,85 1000 Wall1
24,5 0 5 53 2 6,85 1000 Wall1
24,7 0 3 53 2 6,85 1000 Wall1
25 0 0 53 2 6,85 1000 Wall1
25,1 0 5 53 2 6,85 1000 Wall1
25,2 0 9 53 2 6,85 1000 Wall1
25,3 0 15 53 2 6,85 1000 Wall1
25,35 0 0,02 53 2 6,85 1000 Wall1
25,4 0 0,03 53 2 6,85 1000 Wall1
25,45 0 0,04 53 2 6,85 1000 Wall1
25,48 0 48 53 2 6,85 1000 Wall1
25,49 0 0,06 53 2 6,85 1000 Wall1
25,5 0 0,08 53 2 6,85 1000 Wall1
25,5 0 7 53 2 6,85 1000 Wall1
25,5 0 13,5 - - 6,85 1000 -