PIPESIM FPT User Guide

Proprietary Notice

Copyright 1983 - 2004 Schlumberger. All rights reserved. No part of this document may be reproduced, stored in a retrieval system, or translated in any form or by any means, electronic or mechanical, including photocopying and recording, without the prior written permission of Schlumberger. Use of this product is governed by the License Agreement. Schlumberger makes no warranties, express, implied, or statutory, with respect to the product described herein and disclaims without limitation any warranties of merchantability or fitness for a particular purpose.

Patent information Schlumberger ECLIPSE reservoir simulation software is protected by US Patents 6,018,497, 6,078,869 and 6,106,561, and UK Patents GB 2,326,747 B and GB 2,336,008 B. Patents pending.

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PIPESIM

Contents -3-

PIPESIM Revision Record Revision Description A (July 1999) Original release for Build 24 B (March 2001) Revised to reflect PIPESIM

Revision B FPT

Table of Contents

PROPRIETARY NOTICE ..............................................................................2 PATENT INFORMATION...............................................................................2 SERVICE MARK INFORMATION.....................................................................2 TRADEMARK INFORMATION ........................................................................2 CONTACT INFORMATION ............................................................................2 PIPESIM ................................................................................................ 3 CONTENTS...............................................................................................4

1 INTRODUCTION................................................................................. 7 DYNAMIC ECLIPSE LINK .............................................................................7 LOOK-UP TABLES......................................................................................9 COMPOSITIONAL TANK MODELS................................................................10 SUMMARY OF CAPABILITIES .....................................................................11 SUMMARY OF CURRENT LIMITATIONS........................................................12

2 PROGRAM OVERVIEW ................................................................... 15 MAIN SCREEN ........................................................................................15

3 THE MAIN MENU COMMANDS....................................................... 17 FILE MENU.............................................................................................17

3.1.1 Open .......................................................................................17 3.1.2 Save........................................................................................17 3.1.3 Save As................................................................................... 17 3.1.4 Print.........................................................................................17 3.1.5 Print Preview...........................................................................17 3.1.6 Print Setup ..............................................................................18 3.1.7 Recent models ........................................................................18 3.1.8 Exit ..........................................................................................18

EDIT MENU ............................................................................................18 3.1.9 Undo .......................................................................................18 3.1.10 Cut ..........................................................................................18 3.1.11 Copy........................................................................................18 3.1.12 Paste.......................................................................................19

MODE MENU ..........................................................................................19 BUILD MENU ..........................................................................................19

3.4.1 General .................................................................................... 19 3.4.2 Reservoir .................................................................................. 19

3.4.2.1 Eclipse model reservoir specification ..............................................................................................19 3.4.2.2 Look-up table reservoir specification...............................................................................................20

3.4.2.2.1 CASE STUDY MODE ..............................................................................................................21 3.4.2.3 Compositional Tank model reservoir specification ..........................................................................22

3.4.3 Select Network model(s) .......................................................... 23

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Contents -5-

3.4.4 Well mapping ........................................................................... 24 3.4.4.1 Eclipse model well mapping............................................................................................................24 3.4.4.2 Look-up table well mapping ........................................................................................................25 3.4.4.3 Compositional Tank model well mapping....................................................................................26

3.4.5 Define Events..........................................................................26 3.4.6 Flowrate constraints................................................................ 28 3.4.7 Select auxiliary properties....................................................... 29 3.4.8 Eclipse tolerances................................................................... 30 3.4.9 Advanced settings................................................................... 31 3.4.10 Customise output .................................................................... 33 3.4.11 Configuration...........................................................................34

OPERATIONS MENU ................................................................................35 3.1.13 Run .........................................................................................35 3.1.14 Pause......................................................................................35 3.1.15 Restart ....................................................................................35 3.1.16 Abort .......................................................................................35

OUTPUT MENU .......................................................................................36 3.1.17 Results Viewer/Postprocessor ................................................ 36 3.1.18 Reports ...................................................................................39

3.1.18.1 Output (.RPT file) ....................................................................................................................39 3.1.18.2 Custom Summary (.CSF file) ..................................................................................................39 3.1.18.3 Events Log (.FPE file) .............................................................................................................39

3.1.19 Customise output .................................................................... 39 3.1.20 Re-run Network.......................................................................39 3.1.21 Reload restart data ................................................................. 40

APPLICATIONS MENU ..............................................................................41 3.1.22 PS-PLOT................................................................................. 41 3.1.23 Network, PIPESIM and Editor ................................................. 41 3.1.24 Running...................................................................................41

WINDOW MENU ......................................................................................41 3.1.25 New Window ...........................................................................41 3.1.26 Cascade,Tile and Arrange Icons............................................. 41

HELP MENU ...........................................................................................42 3.1.27 FPT Help................................................................................. 42 3.1.28 About FPT ........................................................................... 42

4 BUILDING AND RUNNING A MODEL............................................. 43

5 CASE STUDIES................................................................................ 47 DYNAMIC ECLIPSE LINK CASE STUDIES .....................................................47 LOOK-UP TABLE CASE STUDY ...................................................................47 TANK MODEL CASE STUDY .......................................................................47 TUTORIAL EXERCISES .............................................................................47

5.1.1 Exercise 1: Building a Compositional Tank model linked to a simple surface network ..................................................................... 47

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5.1.2 Exercise 2: Produce a Custom Summary File that can be used to generate a look-up table. .............................................................. 49 5.1.3 Exercise 3: More complicated EVENT logic and flowrate constraining wells. ............................................................................. 51

APPENDIX A: RESERVOIR DYNAMICS .............................................. 53 A1: VOLUME DEPLETION RESERVOIRS .....................................................53 A2: GAS CONDENSATE RESERVOIRS .......................................................54

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Chapter 1: Introduction - 7 -

1 INTRODUCTION The FPT interface is designed to allow the construction, simulation, and data post-processing of surface pipeline networks coupled with a reservoir model to simulate the system performance over time. In addition complex conditional and/or time events can be executed during the simulation. The reservoir can be modelled by either; 1: the GeoQuest Eclipse reservoir simulation program (via the Open Eclipse link) or 2: a single, or series of, look-up tables or 3: compositional tank models. The network models are constructed using the Network graphical user interface and solved using its calculation engine. This is a general network solver, which performs a rigorous heat balance on the network and is capable of coping with networks containing loops, pieces of equipment such as separators, compressors, etc.

Dynamic Eclipse link Network models the surface Network from the bottom hole conditions to the supply/distribution point while Geoquests Eclipse reservoir simulator is used to model the reservoir. FPT passes flowrate targets to Eclipse and Network in order to try to converge on bottom-hole conditions. PROS: An industry standard simulator simulates the reservoir. Phase flowrates are dependent on current flowrates from all wells and reservoir history.

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Full account can be taken of the reservoir geometry and aquifer behaviour etc. CONS: Simulation time is significantly longer. Need to set-up the communication link from the Eclipse simulator based on a UNIX workstation to FPT based on a PC. Need to purchase OpenEclipse from Geoquest and install it properly. It is much harder to converge on a solution between Network and Eclipse. Capabilities: Can model deliverability systems that have pressure specified sinks. Can model blackoil Eclipse reservoir models in both Engineering and SI units. Can flowrate constrain all source wells. Limitations: Cannot model surface networks which have flowrate specified sinks. Cannot model compositional Eclipse models. Construction of the overall Eclipse linked model involves first providing the name of the Eclipse model and on which server/workstation it is located on the Network. This model contains the time stepping information that will be used to control the surface network and also decides when wells will be turned on or off. This field planning data can be overridden by events defined in the field events editor. It also contains the flowrate and pressure limits that are to be imposed upon the wells. These can be ignored in deliverability mode where the maximum capability of the surface network is used to calculate the flow from each well, or obeyed in the usual running mode. Up to five network models can be linked to the Eclipse model, so injection and production networks can be modeled separately. The surface injection network can be ignored which significantly reduces simulation time.

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Chapter 1: Introduction - 9 -

Look-up tables Reservoir properties are taken from a table defined in an ASCII text file, which provide pressure (and optionally pressure and watercut) as a function of cumulative production of oil, liquid, or gas.

Sample decline curve

0

1000

2000

3000

4000

5000

0 5 10 15

Cumulative liquid production [mmstb]

010203040506070

Pressure [psia] GOR [scf/stb] Watercut [%]

PROS: Very fast reservoir modelling as no iteration is required unless conditional logic in the field planning demands that a timestep be run again. Tables can be generated in other packages such as Excel, by Eclipse, by MBAL etc. and then read into FPT. This is the easiest form of reservoir modelling to set-up and use. Everything is included in the FPT package, no third party software is required. CONS: Phasic flowrate behaviour is NOT dependent on total flowrate. All wells linked to a decline curve have the same pressure, and also the same watercut and GLR if that is defined in the table. Capabilities: Full FPT capabilities are available through look-up table reservoir modelling. Up to 500 look-up tables can be defined containing up to a total of 1500 lines of data. Limitations: No way to change watercut and/or GLR in a compositionally defined Network model. Running from look-up tables generally produces results of lower fidelity than from a dynamically linked Eclipse simulation but generally will significantly reduces simulation time and will be particularly useful where: an Eclipse model is NOT available, or

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to perform a preliminary screening of field plans before performing a time-consuming high-fidelity simulation using a true reservoir simulation package such as Eclipse.

Compositional tank models

Well Well

User supplied composition, initial volumetric

Aquifer

Here the reservoirs are modelled by defining the geometry of a simple cylinder containing a user-supplied volume of fluid (either in terms of liquid or gas). Given a user supplied composition, this tank is then depleted (equations describing the depletion rate are listed in Appendix A) via wells mapped to it, hence leading to pressure decline and possible composition changes. Simple aquifer models and fluid injection options are also available. PROS: Relatively straightforward to set-up with no third party software. Full compositional modelling is performed upon the fluid in the reservoir to obtain the correct pressure. CONS: No way to change the watercut in the tank model without injecting a fluid stream containing water. Capabilities: Simple aquifer (influx rate or volume replacement) and fluid injection options are available. Product streams can be gas, liquid, or the tank mixture. Limitations:

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Chapter 1: Introduction - 11 - Aquifer influx does not cause a gradual watering out of the well but a sharp cut off when the aquifer is deemed to have raised the water level in the reservoir to the well perforation point. Simple tank geometry is assumed. A tank is merely a cylinder that does not account for any pore volume reduction as fluid is taken from the reservoir. No facility for blackoil tank modelling at present in FPT.

Summary of Capabilities i. The program links the Network surface network simulator

running on a PC to the GeoQuest Eclipse reservoir simulation program running on a UNIX workstation. Field depletion characteristics can be obtained for analysis with either the Eclipse input file providing maximum flowrates etc from the wells or with the surface Network(s) provided to Network constraining the Eclipse wells (maximum deliverability mode) or a combination of these two modes.

ii. FPT allows events to be specified either at certain timesteps, or conditionally upon targets being reached, or exceeded etc, e.g. if the watercut in branch XXX goes above 95%, shut well Y off.

iii. FPT allows multiple Network models to be linked to a single Eclipse model.

iv. Data is stored in a single file and can be post-processed via the post-processor in the FPT program. This allows data to be shown for individual wells, Network nodes, and branches throughout time. The entire set or wells, nodes, or branches in the current model can be shown at any given time. This data can be output to a Custom Summary File where it can be printed or loaded into a spreadsheet for further analysis, or plots can be produced and viewed via Schlumbergers PSPLOT utility.

v. The FPT Field Planning Tool also allows provision to enter basic look-up tables so that the reservoir can be modelled in terms of pressure, watercut, and GLR being a function of cumulative depletion of liquid, gas, or oil. The simulation can then be performed with Network wells being mapped to these tables (either one table per well or groups of wells to one table etc.) and the results post-processed as above. This is usually much quicker than running an Eclipse case study and doesnt require the user to have Eclipse at all.

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vi. FPT allows a Network model to be linked to simple compositional tank models where pressure decline is calculated from flash calculations on the fluid volume in place in a tank of given geometry. Simple aquifer and fluid injection models are also available in this mode.

vii. Simulation output can be customised to the users wishes and additional output can also be selected via the Auxiliary Properties dialog which allows branch information to be recorded, displayed, and acted upon in the events editor.

viii. The system is fully interactive and the simulation can be paused/stopped at any time and changes/additions made to events, output from the simulation etc. and/or plots produced during runtime.

ix. Flowrate constraints can be imposed on individual wells in the Network models. These wells will be automatically choked back (if necessary) to meet production requirements.

x. Gas lift rates, well PI values, and compressor horsepower settings can be set and/or changed from the Events Editor.

xi. The look-up table editor now enables the user to specify a case study mode for FPT enabling different scenarios to be run in batch mode and the results analysed in the postprocessor.

xii. Group flowrate constraints imposed in an Eclipse input file can be honoured by the FPT.

Summary of current Limitations i. At present only one Eclipse model can be linked to a set of

Network models (although this may contain multiple reservoirs separated by impermeable rock).

ii. Open Eclipse reports quantities in terms of flowrate, watercut, and GLR and does not deal with compositional descriptions therefore, at present, the Network models can be operated in Black Oil mode only. In 'Look-up table mode' it is possible to vary pressures at sources with cumulative production from a reservoir table in COMPOSITIONAL mode but watercuts and gas-liquid ratios etc. are fixed at the Network model building stage

iii. The Event GUI does not allow multiple conditional logic at present, e.g. if time is greater than 2000 days AND the flowrate at the sink is less than 5000 STB/day then set the pressure at the sink to 700 psia. This will be in the future release.

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Chapter 1: Introduction - 13 - iv. Well efficiencies cannot be used in the Eclipse 100 model as these are not passed to FPT and will cause discrepancies in the results and reported cumulative productions between FPT and Eclipse. FPT has the following limits: Maximum number of wells: 256 Maximum number of branches: 512 Maximum number of nodes: 512 Maximum number of stored timesteps: 256 Maximum number of auxiliary properties: 500 Maximum number of Eclipse models: 1 Maximum number of Network models: 5 Maximum number of events: 512 Maximum number of schedule 'bean' lists: 99 Maximum number of look-up tables: 500 Maximum number of data lines in all look-up tables: 1500 Maximum number of tank reservoirs: 50

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Chapter 2: Program Overview - 15 -

2 Program Overview Main Screen This is how the FPT system will appear when first run with the windows cascaded. The menu system will usually be worked across from left to right in building, running, and then analysing the results from a simulation (see Chapter on Building and Running a Model). All the windows are scrolled to the bottom of their respective display areas and this is where any new information will be written.

The windows have the following functions: 'Messages' Displays simple lines of information about all

processes and operations performed both during simulation (primarily running of external applications such as Network and performing remote commands to the Unix Workstation) and

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the results of user operations, e.g. loading files, saving files, launching text editors etc.

'Simulation progress' Displays information on the current operation

and state of a running simulation, e.g. current timestep, whether Eclipse or Network is being run.

'Timings' This dialog merely displays a list of times at

which each timestep in a simulation is completed which can be useful in analyzing why a solution is taking some time.

'Errors and warnings' Displays errors and warnings during runtime

and occasionally if an application cannot be run, usually because it is not set up correctly in the 'Configurations' dialog. Some errors are deemed fatal and cause the window to display itself from a minimized state while others are deemed non fatal. In the latter case, the window is not restored and therefore it is always useful at the end of a simulation (even if 'Simulation completed' is displayed) to restore this window and examine any messages found.

'Field Planning Events' Any events that are defined in the Field Planning dialog and are performed during a simulation (such as wells turning on and off) will appear in this window. They are displayed as a description of the action, the time it occurred at and the iteration (if necessary) at which it was performed. When Network is re-run at a timestep, all the events leading up to this timestep will also be displayed in this window. The Field Planning Events log file (.FPE) contains a complete LOG of all the information displayed in the window throughout a simulation, so that data is not lost off the top of the window. This file can be viewed by selecting Output>Reports>Event Log (.FPE) from the main menu.

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Chapter 3: Main Menu Commands - 17 -

3 The Main Menu Commands File Menu

3.1.1 Open

If you want to open an existing model (to continue working on it or to copy it to another place) then choose this option. A file menu will

appear allowing you to choose the file that is to be opened. FPT model files have the extension .fpt.

3.1.2 Save

The Save command allows the user to save the current FPT model to disk. The model is saved under its current name and the user is

NOT prompted for a new name. The file is saved with the .fpt extension.

3.1.3 Save As

The Save As command is used to save the current model to a new location, copy the model, give the model a new name etc. The user

is prompted for the filename and new location of the model file. This can also be used as a shortcut to creating new models as you can open an existing file, edit it, and then save it under a different name.

3.1.4 Print

This command sends the contents of the currently active FPT window to the printer. The window can be one of the five main

windows or a Scrap window containing notes, diagrams etc. These scrap windows can be created from the Window : New menu item. Before printing the user is given the choice of which printer to use and its settings from the standard Windows dialog box.

3.1.5 Print Preview This command allows the user to see a preview of what the currently active window will look like when printed before printing. Generally it is advisable to maximise the window in question before selecting this

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option to give the most accurate representation of what the final printed output will be like.

3.1.6 Print Setup This option allows the printer settings to be adjusted from the general Windows Print Settings dialog.

3.1.7 Recent models

This option brings up a dialog containing the last 20 used FPT model files, the most recently used being at the top of the list.

Clicking on the model file of interest will cause it to be opened and reloaded. Clicking on OK effectively leaves this dialog without making any selection.

3.1.8 Exit Choose the Exit option to terminate FPT. The software will prompt the user to save any currently loaded model, under the same or a different name as desired. FPT will then shut down. Note, any information in Scrap windows (see Windows Menu: New Window) will be lost when the program shuts down.

Edit Menu These options all operate on text and graphics in the main FPT windows and scrap windows.

3.1.9 Undo This option undoes the last operation made in a window, be it typing text, resizing a bitmap, pasting a bitmap, deleting a bitmap or text etc.

3.1.10 Cut

This option removes the current text/graphic selection and puts it in the windows clipboard.

3.1.11 Copy

This option copies the current text/graphic selection and puts it in the windows clipboard.

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Chapter 3: Main Menu Commands - 19 - 3.1.12 Paste

This option takes the contents of the windows clipboard and puts it at the current cursor position in the current FPT window. This is

useful for example in pasting Networks into a scrap window.

Mode Menu This menu allows the selection of the current operating mode of FPT, e.g. Dynamic Eclipse link, look-up table, or compositional tank model mode. It should usually be the first thing that is set when building a new model.

Build Menu

3.4.1 General This menu item will bring up the general description dialog allowing you to give a heading for the current model that will be used as the default for all plot headings. It also allows the specification of a longer description for the model that will appear whenever the model is loaded.

3.4.2 Reservoir

This option will take you to a screen dependent on which MODE FPT is currently set-up in. The following sections describe each of

the different reservoir specification screens depending on the mode of operation: 3.4.2.1 Eclipse model reservoir specification At present, only one Eclipse model can be specified. The location of the Eclipse input file should be entered in the field shown below. It is important to remember that '/' is used under Unix, as opposed to the '\' in Windows and DOS.

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If an incorrect file name is entered, when the 'Update BOTH well lists' button in the Eclipse well mapping dialog is pressed, a large list of 'DUMMY' wells will be shown, one for each Network source or SINK, and all will be marked as 'OFF'. 3.4.2.2 Look-up table reservoir specification This dialog enables the data held in the look-up tables to be defined, loaded, edited, and removed from the system. This table enables two modes of operation to be selected: Normal Cumulative Production based reservoir decline described below and Case study mode. The first step in defining a look-up table (which may be taken from an existing ASCII text file containing reservoir simulation data), is to define what data is in which column. A prerequisite is that there is an independent variable column and a pressure specification in each row of the table data. Following is a description on how to set up and load in an example look up table. The properties can be selected/deleted by clicking in the properties list box. Once the required properties have been entered, it is suggested that the blank template table be saved using the Save table button. This prompts for a file name that will be used to identify the table selected in the drop-down list box above this button. Clicking on the Text Editor button will then allow the table (.TBL) file to be edited. A file similar to the following should be observed when loaded in the editor: Cum. Oil Pressure Watercut GLR

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Chapter 3: Main Menu Commands - 21 - [mmSTB] [psia] [%] [scf/STB] -----------------------------------------------------

LOOKUPTABLEDATA ENDOFTABLEDATA Data can now be entered or copied from another text file between the two labels e.g. It is important that these two keywords surround the data you wish to load in otherwise you will load the table and see NO DATA. Cum. Oil Pressure Watercut GLR [mmSTB] [psia] [%] [scf/STB] -----------------------------------------------------

LOOKUPTABLEDATA 0.000 4000.000 0.000 500.000 0.150 3900.000 2.000 500.000 0.200 3700.000 10.000 550.000 0.300 3800.000 15.000 550.000 0.500 3500.000 15.000 550.000 0.750 3400.000 20.000 600.000 1.000 3300.000 25.000 600.000 1.250 3200.000 30.000 650.000 1.500 3100.000 35.000 650.000 1.750 3000.000 40.000 700.000 2.000 2900.000 45.000 700.000 3.000 2800.000 50.000 800.000 5.000 2700.000 55.000 900.000 10.000 2600.000 60.000 1000.000 15.000 2500.000 65.000 1100.000 ENDOFTABLEDATA This file can now be saved in the text editor and then loaded into the Look-up table editor dialog using the Load table button. The data can be sorted in order of increasing cumulative xxxxx using the Cumulative sort button or the table can be removed from memory (but not from the disk) using the Delete table button. 3.4.2.2.1 CASE STUDY MODE By switching on the Case mode switch, FPT is instructed to enter a new mode of operation where individual cases (numbered) can be entered into the look up table and each case in turn will be run. This enables various scenarios to be run in a batch and the results analysed in one FPT model.

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Case or Time must be specified as the independent variable followed by a list of properties as normal for a look-up table. The simulation will work down this list case by case, and events can be used as normal to change the network based on case number etc. One difference is that the table can contain both a pressure and flowrate specification, and the radio buttons can be used to select which will be passed as the boundary condition to the solver. This is useful in comparing flowrates and pressures calculated by a reservoir simulator with the flowrates/pressures required by the surface network. The Customise Output dialog allows table values to be displayed with other Source information. 3.4.2.3 Compositional Tank model reservoir specification The following dialog allows the definition of up to 50 simple tank models that can then be linked via well mapping to Network. Tanks can have simple aquifer models added to them by defining EITHER a voidage replacement rate or an aquifer influx rate. Injection fluids can also be defined in terms of a gas or liquid injection rate, the composition of which is supplied via a PVT file. Each tank model needs to be first defined by giving it a unique name and an initial fluid composition via a PVT file generated from the 'Compositional Fluid Dialog' in PIPESIM or Network. Cycling through the different tanks can be achieved using the < and > buttons or entering an index number in the box in between the arrows. To delete a tank, call it UNUSED or simply don't map any wells to it.

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Chapter 3: Main Menu Commands - 23 -

The geometry of the tank reservoirs needs to be defined in terms of the depth of the top of the reservoir and the initial reservoir bottom/ water contact point. Additionally, a default depth for the well perforation depth can be entered but otherwise defaults to halfway between the initial top and bottom of the reservoir. The initial conditions of each tank reservoir defined must then be entered. These

include the initial reservoir pressure and temperature (which at present is NOT changed throughout the simulation) and either a gas or liquid fluid volume in place. The simulation will then calculate the pore volume of the tank based on the top and bottom dimensions, the fluid composition and this specification at the given temperature and pressure. The aquifer and initial fluid injection properties and rates can then be defined. IMPORTANT: Even if the reservoir has no initial fluid injection but it is foreseen that injection will be used, the composition file for the injection fluid must be specified here, along with e.g. zero flowrate. NOTE: PVT files must be generated from the COMPOSITIONAL specification dialog in either PIPESIM or Network and then 'Exported' as a PVT file.

3.4.3 Select Network model(s)

Up to five Network models can be simulated in an overall reservoir/surface Network simulation. The location of these Network

models should be entered in the fields shown below or the 'Browse' button can be used to search for a Network model. Once a Network has been specified, it can be modified using the Network graphical user interface, as specified in the 'Configuration' dialog, by clicking on

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the appropriate 'Edit' button. This MUST BE DONE at least once for any previously created Network model to be used with FPT. The individual Network models can also include multiple Networks using the multiple Network feature of Network.

3.4.4 Well mapping

This option will take you to a screen dependent on which MODE FPT is currently set-up in. The following sections describe each of

the different well mapping dialogs depending on the mode of operation: 3.4.4.1 Eclipse model well mapping This dialog allows the user to connect the wells in the reservoir simulation to the sources and sinks present in the Network Networks. The two lists, which are initially blank, can be modified in the following ways in order to link wells to one another or turn them off etc: Clicking on 'Update BOTH lists' will order the system to search through the Network input files specified in the 'Select Network models' dialog for the names of all the sources and sinks in these models. They will then be displayed along with an index and a model index (1-5) indicating the Network model they belong to. A query will also be made via Open Eclipse to obtain the names of all the wells in the reservoir model specified in the 'Select Eclipse model' dialog. Unfortunately, this list may NOT have any injection wells, therefore the system adds 'DUMMY' wells for every Network source or sink. These DUMMYs are initially 'OFF' but can be turned on and have their name

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Chapter 3: Main Menu Commands - 25 - and type modified as detailed below. This process may take a few seconds for large models. Automatic mapping of the wells will be attempted by matching names but this should always be checked before proceeding with a simulation. WARNING: Before pressing this button, it is advisable to first save all your model building information as , very occasionally, it is possible to get 'stuck' in this dialog if Eclipse fails to run properly! Clicking on 'Update Network wells' just obtains the Network wellnames. This is faster than the above and will always contain a complete list of sources and sinks. If no wells appear check that you have edited the network models and exported the files using either File>Export engine files, or the FPT button on the Toolbar. Once a well in either or both lists has been selected, the 'Toggle ON/OFF' button can be pressed. This causes the well(s) in question to be ignored as far as convergence of the systems is concerned. This has two purposes. Firstly, some sources and sinks have no mapping to the reservoir wells e.g. a floating production vessel sink, and must therefore be ignored as in the example shown above. Secondly, should a well be causing a lot of problems during convergence the user may wish to interactively 'forget' about it by simply turning it off in this dialog. As can be seen, the model index number changes to 'OFF' for a source/sink that is to be ignored. In order to enter Eclipse wells that aren't automatically detected or to view the type etc of well, once a well from the reservoir list is selected, hitting the 'Edit Eclipse name' button will bring up another dialog in which the well type and name can be entered/altered. Finally, selecting a well in each list and clicking on 'MAP WELLS' causes these wells to be 'connected'. The information box just gives some short messages on the current status, e.g. 'wells mapped.' 3.4.4.2 Look-up table well mapping This dialog allows the look-up tables to be mapped to wells (or sources) in the Network model(s) selected. Multiple wells can be mapped to a single table, or each well can be mapped to a separate table.

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Update Network wells searches through the Network models selected in the 'Select Network model' dialog and produces a list of wells, sources, and sinks from that model, as well as acquiring the branch names, node names, and connectivity of the surface Networks. All these are assumed to be active and must then be mapped to a table or turned off using the options described

below. Edit tables brings up the look-up table editor dialog which can be used to select table files to be used, as well as selecting what data they contain, sorting the data etc. MAP takes the selected well and/or table and maps them to each other. UNMAP unmaps the well(s) selected from any tables. 3.4.4.3 Compositional Tank model well mapping This dialog allows the tanks defined in the tank model definition dialog to be mapped to the sources in Network in a similar way to look-up table well mapping. Multiple Network sources can be selected and then linked to a particular tank description and then mapped or unmapped using the appropriate button. Alternatively, the product description can be changed for the selected wells by clicking on the Gas, Liq, or Mix buttons. The perforation option allows selected wells to have their perforation depth changed. If/when the water contact point in the tank reservoir that the well is linked to reaches this point, the well be shut in.

3.4.5 Define Events

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This editor allows both TIME dependent and CONDITIONAL events to be defined along with the overall times and timestepping for the

simulation (LOOK-UP tables and TANKS ONLY). For an Eclipse model, the Eclipse input file will define the initial and end times of the simulation and Eclipse will control the timestep size(s). Events can be defined using the options available in the drop-down list boxes in the 'Event editing' section of the editor, and then the defined event can be added to the list by selecting the Add button. INVALID events are flagged by a ? appearing next to the Type. The combinations of drop-down list boxes change automatically depending on the type of event selected, e.g. if a Type TIME event is selected then the first Name and first Property box are rendered inactive and only a qualifier and value are expected to define the condition of the event. Similarly, if a TURN ON command is selected in the THEN drop down list box, then only a TYPE (Source or Sink SRSK, or Branch BRN) and a name is expected, NOT a property or value. Insert can be used to add an event at a point in the event list selected by the user in the list of events window. Delete can be used to remove events, or groups of events if multiple events are chosen using the CTRL and/or SHIFT keys in conjunction with the mouse in the event list window. SCHEDULING This drop down list box allows the various schedules to be defined. By default, events are placed in a list of NON-SCHEDULED events (NONE)

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which means that these events can occur in any order and/or all at once. This implies that if multiple events all reliant on a particular condition being met are defined then, once this condition is met, all the events take place at once! Contrast this with events placed in a 'BEAN LIST' numbered 1 to 99 in the schedule list. Events in these lists can only take place once the events above them in the list have taken place, even if their condition may have been met but the condition for an event above it in the list hasn't. Further, only one event in these lists will be performed at any single iteration. This allows well schedules to be defined. For example, a list of wells to be turned on in turn can be defined to meet a specified production target. Only events that are in the currently selected schedule bean list (or NONE) are displayed in the main window. SORTING Events can be sorted by the various parameters listed in this drop down list box. If events are sorted, it is highly inadvisable to restart the simulation or re-run Network at a timestep before reloading the restart data. This is because the events that have been performed at that timestep are stored by numerical index, NOT by their description. Therefore the wrong set of events could be performed on the re-run/restart giving invalid results. For similar reasons, events cannot be sorted during the simulation. EXPERT MODE This button first allows the models input file to be saved (so that any modifications made since the last save are available in the input file that will then be opened up for editing. An expert user can then modify the text strings that describe the events at the top of the FPT input file and then resave it as a text file. If this file is then reloaded, all the new edited events will be reloaded and checked for validity. INVALID events are flagged by a ? appearing next to the Type.

3.4.6 Flowrate constraints

This dialog allows the user to specify any flowrate constraints that they wish to impose upon the wells/sources in the Network

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Chapter 3: Main Menu Commands - 29 - model(s). It is also possible to put a flowrate constraint on a sink branch (indicated by a negative number in the index column of which Network model the source/sink belongs to). It should be noted that sinks connected to sources of different compositions can take significantly longer to solve using Network due to the fact that the changing composition of the flow out of the sink leads to a 'moving target' for the flowrate constraint algorithm. Wells can be selected either individually or in groups and then the type of flowrate restriction to be imposed (LIQUID, OIL, GAS) selected from the drop down menu. After the flowrate constraints value has been entered in the box below, this constraint can be imposed upon the selected well(s) by pressing 'Apply'. Only one type of constraint is allowable per well and it is HIGHLY RECOMMENDED that the OIL flowrate constraint is NOT used when linking to Eclipse. ANY WELL that has a flowrate constraint imposed upon it must have a CHOKE added during the NETWORK editing phase in the branch connected to the well/source. This CHOKE should have its bean size set to equal to or greater than the diameter of the tubing. Clicking on remove will remove any constraints imposed on the selected well(s). MINIMUM flowrate constraints can also be set for wells in the same way by first using the list box to select MINIMUMS rather than MAXIMUMS. When a source or sink violates this minimum flowrate it will be switched

off at the NEXT timestep.

3.4.7 Select auxiliary properties

Due to the large quantities of data being

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produced by Network at a single timestep, this dialog allows the user to select what properties are to be stored at each timestep and for which branch. These properties can be used in the Field Planning dialog to test against and, along with the ability to re-run Network at any previous timestep allow the user to obtain any data at any time. The branches available in the models are displayed and can be added to the 'Branches selected' list (which contains the branches for which auxiliary data is to be stored) by double clicking on the branch name or selecting it then using the Add button. Once added, the branch can be selected in the 'Branches Selected' list box and then properties can be added/deleted from the 'Selected Properties' box by clicking on the relevant property. The information box will provide some guidance and comments as to what has been done or what is expected of the user! Selecting a branch from the Branches Selected list box and then pressing delete removes all references to data to be stored for that branch. Up to 500 auxiliary properties can be selected i.e. 250 wells could have two properties recorded each, or 50 wells could have 10 properties each.

3.4.8 Eclipse tolerances

This dialog allows the convergence tolerances for the simulation to be set. The Network will be deemed to have converged on a

balanced solution at each timestep if all the pressures for non mapped wells (See Look-up table mapping dialog or Eclipse to Network well mapping dialog) are within the well BHP tolerance. This tolerance is given as a percentage of the total BHP, the liquid flowrates are within the liquid tolerance and the gas flowrate within the gas tolerance. The liquid tolerance can be imposed in two ways: i. On the total oil + water flowrate; or ii. On each phase separately. The latter tends to increase simulation time (sometimes dramatically) as the percentage change in a liquid phase may change dramatically but have little effect on the overall performance of the well. The convergence method has two options:

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Chapter 3: Main Menu Commands - 31 - Obey Eclipse/User limits, which is the preferred mode of operation in which the well flowrate limits specified in the Eclipse input file or modified by the user during runtime using the 'Well detailed information dialog' are imposed on the system. Convergence can therefore be achieved (e.g. for a production well) when a flowrate limit is reached and the BHP required the Network simulation is higher than that specified by Eclipse as the Network well could be choked back to give the specified BHP. The reverse is true for injection wells. In this mode, flowrates are specified to ALL the mapped wells in the NETWORK model, therefore it is imperative that the networks have at least one non-mapped source or sink that is pressure specified. In this mode, group constraints in Eclipse can also be obeyed. Maximum deliverability mode where all flowrate constraints are removed from the wells and the surface Network dictates the flow from the Eclipse reservoir. Because both flowrates and pressures have to be matched for all the wells, this can increase the simulation time dramatically. Two modes are available in this mode now, pressure and flowrate specifying the Network model. When flowrate Q specifying the Network, a pressure must be specified as a boundary condition in the Network for at least one unmapped source or sink. When pressure-specifying Network wells, the IPR relationship from Eclipse is fed, along with the static grid block reservoir pressure, to the mapped Network wells. This can sometimes aid convergence dramatically. It is also the only mode of operation available when all the sinks in the Network is flowrate specified. Clicking on the Advanced button brings up the advanced setup dialog.

3.4.9 Advanced settings

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Care should be exercised in using this dialog to modify some of the parameters used in the simulation which can be used to help optimize the performance of the system but which can also be used to destroy the validity of the results. The Eclipse tolerances determine the mass and pressure tolerances that Eclipse will try to meet by performing Newton iteration steps in its simulation routines until the target flowrates or pressures are met. The 'minimum time between Network runs' allows a timestep (in days) to be specified in which Eclipse will be instructed to move forward in time without running a Network simulation and converging on a solution. This can be useful at the beginning of a simulation when Eclipse typically takes very small timesteps. New wells opening or closing will cause this minimum timestep to be ignored. Care should be exercised particularly with this feature as, although it can speed up the simulation, it can also invalidate results. The SCRDUMP.LOG file is generated in the home directory of the user on the UNIX machine upon which Eclipse is run. This file can get very large and may exceed the disk quota for the users home directory, at which point Eclipse stops. Therefore by default this file is NOT produced. It is however very useful for debugging why an Eclipse link may not be working so, if the model doesnt run properly, switch this option on and then examine the file produced for ERROR and WARNING messages. 'Memory resident engine maximum iterations' specifies the maximum number of cases that will be run by Network before the Network engine will be removed from memory and reloaded if necessary for further calculations. A value of zero is taken to mean 'Install a Network -engine for every calculation and remove it from memory after an individual solution is reached' (i.e. the same as a value of 1). On some computers, installing the Network engine kernel may take some time. Care must be taken NOT to select too high a value as the engine sometimes uses more memory as subsequent cases are performed and the larger the Network model, the more memory is 'consumed'. If too much memory is

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Chapter 3: Main Menu Commands - 33 - used the engine will slow down considerably and any gains from NOT loading it each time will be lost. 'Maximum number of timesteps' specifies the maximum number of timesteps that can be performed in a single simulation. A simulation will be ABORTED if this maximum is reached. 'Maximum number of iterations per time step' specifies exactly that, and can be used to control the maximum time taken for a simulation, particularly if tight pressure and flowrate tolerances are set in the 'Set Tolerances' dialog. Once this maximum is reached, the simulation proceeds to the next timestep even if a solution has not been reached. Convergence at a timestep can be viewed in the 'timestep' display in the Results Viewer/Processor' dialog. If the Network restart facility is requested, it may be possible to speed up simulations. Unfortunately, FPT makes changes to the Network topology which can mean that using the restart facility might actually increase simulation time so care must be exercised in it's use therefore by default it is NOT USED.

3.4.10 Customise output

This dialog allows the user to specify the output they wish to see for each of the custom settings (1 through 6). Each custom setting has

its own set of settings for sources/sinks, internal junctions, and branches. Clicking on the specified type brings up a list of available parameters that can be selected and deselected by clicking on them in the 'Properties' box and/or the 'Selected Properties' box. This box also selects what is placed in the overall .RPT file produced during a simulation. By clicking on the 'Write to .RPT file' check box, this informs the system to write out the selected properties for the selected

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'type' ONLY at intervals specified in the 'Every XXXX days' box. Values of zero indicate output for both Network and Eclipse, in Eclipse mode only, results at every available timestep. By default, only pressures and flowrates for sources and sinks are output. Selecting 'Branches' activates the 'Auxiliary data' button that can be used to access the 'Auxiliary properties selection' dialog.

3.4.11 Configuration

This dialog (located under the Build menu option) allows the user to specify the configuration of their system e.g. the location of

Schlumberger software on the local PC or Network, which text editor to use. The Browse buttons allow the user to search through all attached drives to find the program they are looking for. When an Eclipse link is NOT required, the FPT/OE configuration section will be grayed out as it is unnecessary to specify these settings if an PC/UNIX link is not

required. For a dynamic Eclipse link, the host name and commands for the location of the batch files used to communicate with the 'FIVEMAST' program on the Unix Workstation are required. You need to have permission on the Unix machine to run executables. The name of the FIVEMAST executable is the name of the script file required to run the 'FOREMAST.EXE' program on the Unix workstation. Sample files are supplied upon installation but will probably need to be modified in order to run the Open Eclipse interface successfully as various environment variables and paths have to be set up before executing the 'FOREMAST program'. The password, if used by the batch files, is NOT saved and will need to be re-entered at each FPT session.

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Chapter 3: Main Menu Commands - 35 - Operations Menu

3.1.13 Run

This option will start an FPT simulation. The user is prompted for a filename to run the model with. This can be the same filename as a

previous model in which case any existing results will be overwritten, or it can be a completely new filename. The simulation will then proceed and its progress can be followed in the Simulation window or through the Results Viewer/Postprocessor describe later.

3.1.14 Pause

An FPT simulation is interactive and the user can use this option to pause the simulation at the next possible pausing point. This can be

very useful if the user wishes to add many events before the simulation can proceed to the next timestep or decide that this timestep has converged successfully. It can also be used so that the output files from the Network solver can be looked at before the next Network simulation overwrites them.

3.1.15 Restart

This option does one of two things:

It restarts, or un-pauses, a previously paused simulation that will then carry on. If the simulation hasnt been started then it brings up the restart dialog and allows the simulation to be restarted from a previously simulated timestep. Once the time to start from has been selected, the user is prompted for a filename to run the simulation under as before, and then the simulation will proceed from the given timestep.

3.1.16 Abort

This option, after asking for confirmation from the user, stops any currently running simulation at the next possible time. This may take

a few moments if, for example, FPT is waiting for the Network solver to finish solving.

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Output Menu

3.1.17 Results Viewer/Postprocessor

This dialog is the main data analysis dialog, which enables data to be reloaded, viewed, manipulated, output to custom files etc.

The many options available using the buttons located at the top of the dialog are described below. Button/selector Function 'Eclipse/Tanks/Net' This toggles between displaying the data produced

from the Network simulations and the data from the reservoir simulation. The currently selected mode is shown in the main data window on the top line e.g. 'Eclipse values'. (Eclipse mode only)

Names/Time This button toggles between showing the current

names of sources/sinks/nodes/branches available for selection and a list of simulation timesteps for which data is available.

Well data Once a well is selected in either of the main two list

boxes, this button can be pressed which brings up the

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Chapter 3: Main Menu Commands - 37 -

'Detailed well data' dialog. This contains reservoir and Network phase flowrates, pressures, pressure limits, and convergence setpoints for the well so that the current state of the well can be viewed. Double clicking on a well in the Name/Time list has the same effect. (Eclipse mode only)

Field Planning Brings up the Field Planning dialog in which events

can be viewed, added, and deleted and sorted (the latter two options NOT being available during a simulation).

Well mapping This brings up one of the dialogs for well mapping to

look up tables or Eclipse wells. During simulation, some of the options in this dialog are unavailable such as re-mapping wells. However, wells/sources/sinks can be turned on and off during runtime which may be useful to manually aid the convergence at a particularly difficult timestep.

Update This button becomes available when viewing

timesteps. During simulation runtime, it causes the list of times that data is available for to be updated, thus showing the progress of the simulation and enabling the data to be viewed and analyzed.

Sources/sinks Sets the display mode to show source and sink data for

either the reservoir or Network. For either of the two buttons listed below, the Network/Eclipse switches are obviously unavailable.

Nodes Sets the display mode to show a list of nodes/junctions

in all the Network model(s). Branches Sets the display mode to show a list of all the branches

in the Network model(s). Edit CSF This starts up a text editor (as specified in the

'Configuration dialog') with a 'Custom Summary File' which is produced from this dialog using the button described next.

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Update CSF This brings up a dialog with three options: Append

Custom Summary File; New Custom Summary File; and Cancel. The first keeps the .CSF file that already exists (if any). The second starts a new .CSF file and deletes any existing file. Both update this file with a copy of whatever is displayed in the main data view window. Therefore, using the Customise option detailed below, data can be arranged in any format and then output to this file at any time(s) of interest. The data is ideal for spreadsheet analysis etc.

Plotting This button brings up the plotting dialog Reload This brings up the 'Reload data' dialog enabling

previously calculated data to be reloaded from the .LOG file. This cannot be done during a simulation as it overwrites data held in memory and could therefore have disastrous consequences to a simulation in progress.

Re-run Net This button brings up the 'Re-run Network' dialog

which enables detailed data to be obtained at a particular timestep by re-running Network at this timestep using the converged flowrates from the simulation. The results may be very slightly different from the simulations but will always be within Network's convergence tolerances. This is because Network uses restart files from previous simulations to calculate a solution more quickly at a given timestep and these affect the initial conditions of its solution. It is highly unlikely that the same restart file will be available when re-running a particular timestep therefore the solution may be slightly different.

Customise This button brings up the 'Customise output' dialog

which can be used to select what and how often data is displayed and written to the main output (.RPT) file.

The custom buttons merely cycle up and down through the 6 custom settings available for viewing data. For example, setting one may show

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Chapter 3: Main Menu Commands - 39 - oil, water, and gas flowrates, setting two may show cumulative flows, and setting three watercuts and gas-liquid ratios etc.

3.1.18 Reports 3.1.18.1 Output (.RPT file)

This option allows the main output report, the contents of which can be customised from the Customise Output dialog, to be viewed

and edited in text editor. 3.1.18.2 Custom Summary (.CSF file) This option allows the user to see and edit the Custom Summary File which is produced from the Results Viewer/Postprocessor dialog and enables reports to be built up to the users requirements and which can be imported quickly into a spreadsheet for further analysis. 3.1.18.3 Events Log (.FPE file) This menu item allows the Events Log to be viewed and/or edited. This file contains the exact contents of the Field Planning Events window during the entire FPT simulation, thus overcoming the limited size of this window and enabling all events to be seen throughout the entire simulation.

3.1.19 Customise output

See section under the Build Menu.

3.1.20 Re-run Network

This dialog enables a specific timestep of a specified Network model to be re-run in order to generate detailed plot and summary

files at that timestep for the specified Network. These can then be viewed using a text editor.

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When a new case is loaded, it may be necessary to first press the 'Reload restart data' button that brings up the appropriate dialog and reads in the solution data created during the reservoir/Network simulation. A timestep and Network model can then be selected and the 'Re-run' button pressed to re-run at that timestep. This task is performed separately to the FPT interface and therefore the user can continue with other tasks. It should be born in mind that while Network is solving this timestep, it is highly inadvisable to start a simulation or run the same Network model at a different timestep (This will NOT stop the FPT interface but will almost certainly NOT work either).

3.1.21 Reload restart data This dialog merely allows the user to enter the minimum timestep to be used in reloading previously calculated data held in the .LOG file. The FPT interface can only store a finite number of timestep data (dependent on the version of the program bought and the computer memory available). Simulations can have many more timesteps, particularly when Eclipse is taking very small timesteps initially in a simulation. This data is stored in the .LOG file and can be read in e.g. every 6 months, every year, every day etc. A minimum timestep of zero means 'try to read in every available timestep' until the maximum storage capability is reached. As FPT can only store a finite number of timesteps in memory, it may be advisable to keep reloading with increasing minimum timesteps until the timespan of interest is completely loaded.

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Chapter 3: Main Menu Commands - 41 - Applications Menu

3.1.22 PS-PLOT

This option runs Schlumbergers PSPLOT plotting utility that can be used to load and plot previously created plot files.

3.1.23 Network, PIPESIM and Editor These options simply launch the application requested from FPT in a similar manner to running the application from a desktop etc.

3.1.24 Running This option lists the applications that have been run from FPT. This may include the Network editor, the plotting utility PSPLOT etc. More importantly, during a simulation, this option may list several operations being performed under FPTs control such as running the OpenEclipse control program on the UNIX machine, running the Network solver etc.

Window Menu

3.1.25 New Window This option creates a new window which can be used as a Scrap window for typing information of interest or note during the model building process, or perhaps pasting a diagram or Network bitmap from the Network interface into for reference. Full Cut, Copy, and Paste as well as Undo functions are available for these and the other FPT windows. The advantage of placing information in these scrap windows is that the information will NOT be lost until FPT is closed and shut down.

3.1.26 Cascade,Tile and Arrange Icons These are standard windows operations that operate on all the available FPT windows.

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Help Menu

3.1.27 FPT Help

This menu item brings up the FPT Online-Help system. Pressing F1 also has the same effect.

3.1.28 About FPT This dialog merely details the current version of the FPT interface that you are using. Clicking on the Schlumberger Address button brings up a further dialog box showing the address and phone numbers of Schlumberger Technical Support. The most important part of this dialog is the build number that you should be ready to supply when ringing or e mailing for technical support

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Chapter 4: Building a Model - 43 -

4 Building and Running a model The process of building a FPT model consists of the following stages: Specifying the mode of operation: dynamic link to the Eclipse reservoir simulator; look-up tables to specify reservoir performance and depletion characteristics; or compositional tanks. The selection of the operational mode determines the options available from the Build menu and also the method used to simulate the system. Look-up tables are generally much faster than Eclipse linked models but are inherently a less rigorous solution to the system. Specifying the Eclipse input file / Look-up tables / Tank Models and Network models that are going to be connected. Mapping the wells in the Network model(s) to look-up tables, Eclipse wells, or Tank models, by obtaining the names of the wells in both systems and connecting them together, while also specifying wells that are not going to be included in the simulation. Specifying any flowrate constraints that you wish to place on any/all of the wells. Selecting any auxiliary properties that are to be stored from Network runs during the simulation and which can be analyzed in the post-processor and also used to test against in the field planning event editor described below. Defining the field planning events that are to be obeyed during the simulation of the model. These include the timing of wells turning on and off; branches turning on and off; and the setting of boundary conditions in the Network model. All these types of events can also be conditional on the flowrates etc. in the model as well as purely time defined. It is important to remember that in look-up table and tank model mode, all the wells are initially considered to be closed and therefore it would be normal to open at least one well at time step zero. Setting the convergence tolerances that are to be imposed on the system, and also setting the mode of operation, i.e. maximum deliverability or obeying Eclipse flowrate limits.

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Setting the configuration of the system, i.e. the name of the host Unix workstation where the Eclipse simulator resides. Once the model has been built, the simulation can be performed using the options in the 'Operations' menu item : 'Run simulation' asks the user for a filename to run the simulation using. A new name can be supplied if old results are to be kept. The simulation is then started and it's progress can be monitored in the 'Simulation progress' window and also some of the options in the 'Output' menu item can be selected to interactively view the simulation results. When the simulation is completed, a 'Simulation complete' message will appear in the message and simulation progress windows. If for any reason, including the user specified abort simulation occurs, a message 'Simulation aborted' will appear, and possibly the 'Errors and warnings' window will contain information as to why the simulation aborted. 'Pause simulation' pauses the simulation at the next convenient point at which the message 'Simulation successfully paused' will appear in the message window. This is useful for two reasons: i. It stops the simulation progressing to another timestep before the user can alter tolerances or change the system in any way, e.g. new flowrate limits could be imposed; ii. It stops the Network engine from being re-run before changes are made to the system (because the Network engine is given as much CPU time as possible, when it is running there may be delays to other processes). 'Restart simulation' has two functions: i. If the simulation is not already running, this will start a simulation in the same way as 'Run simulation' except from a selected timestep or; ii. if the simulation is running and has simply been paused this command 'restarts' it. In Eclipse link mode, if the Eclipse input file has been modified to start from a time other than 0 days, the FPT system will recognize this, keep all previous data up to the restart time, and continue the Eclipse simulation from this point. 'Abort simulation' stops the simulation at the next suitable point and shuts down Eclipse if running in the dynamic Eclipse mode. The 'Output' menu item contains various options to enable analysis and post-processing of the data from an FPT simulation. The options available, and when they are available, are listed below:

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Chapter 4: Building a Model - 45 - Edit .RPT file [post simulation only] Allows a text editor to be used to view and edit the output file produced during a simulation which contains tabulated data for all the output at all simulated timesteps according to what is requested in the 'Customise output' dialog. Edit FPE file [post simulation only] Allows viewing of the FPE file that contains a list of all the events performed during a simulation. It is actually a permanent record of the contents of the Field Planning Events window during the simulation. Edit .CSF file [always available] Allows editing of the Custom Summary File can be produced and appended to during and after a simulation and contains 'snapshots' of the main data window in the 'view current results' dialog. All these files are suitable for importing into a spreadsheet. Results Viewer/Processor' [always] During and after a simulation, the dialog can be used to analyze the data produced from a simulation. Some sample results from time dependent plot files '.PBT' files produced from this dialog are shown at the end of this topic. Customise output [always available] Brings up the dialog to control what output is sent to the .RPT file at each subsequent timestep and also controls the different custom settings available in the 'view current results' dialog. Reload restart file [post simulation only] Allows previously calculated results to be loaded into memory from the .LOG file and analyzed/restarted from. Re-run NET [post simulation only] Allows detailed Network output files to be generated from converged solutions at any timestep.

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Chapter 5: Case Studies - 47 -

5 Case Studies Dynamic Eclipse Link case studies Two case studies are supplied in the DEMOS\FPT\ECLIPSE subdirectory. One is an oil field case study (ECLOIL), the other a gas field case study (ECLGAS). The Network model is a very simple three well gathering system with a pressure specified source. The Eclipse model is also very simple with three producing wells and two water injectors.

Look-up table case study A simple look-up table case study is supplied in the DEMOS\FPT\TABLES subdirectory. The Network consists of a simple three well gathering Network to a pressure specified source with all the three wells linked to single look-up table which tabulates pressure, watercut, and GOR against cumulative production of oil. Some simple event logic to turn wells ON and adjust the sink pressure are also included.

Tank model case study A simple compositional case study is included in the DEMOS\FPT\TANKS subdirectory. This consists of a gathering Network with 5 wells and one pressure specified sink. The wells are split into two groups each of which are linked to separate compositional tanks, although the composition in the two tanks are the same. Event logic is used to open the wells at different times and also to change the sink from pressure specification to production rate specification during the simulation.

Tutorial Exercises

5.1.1 Exercise 1: Building a Compositional Tank model linked to a simple surface network

The reservoir, named BJA1, initially contains 50000 mmscf of gas at a pressure of 4000 psia and a temperature of 250F. The top of the reservoir estimated at a depth of 3800 ft below sea level while the initial

Revision B FPT

water level is estimated to be at a depth of 4300ft. The attached aquifer is expected to provide an estimated 30% volume replacement in the reservoir. There is no fluid injection into this reservoir. The initial composition is 88% methane, 10% ethane, and 2% propane. Three wells are connected to this reservoir. A description of each is given below. These three wells connect via their tubings to a single well head manifold on the seabed which is at a depth of 1000 ft. From this a horizontal flowline of 150000 ft length and 4 inch ID runs to the base of a riser of 5inch ID which goes up to a FPSO which requires a minimum production pressure of 500 psia and should be able to handle the production from this reservoir. Well 1: Mid perfs at 3900ft below sea level, producing the reservoir mixture as a product. Completion is a simple gas PI of 0.002 mmscf/d/psi2. Temperature is the reservoir temperature while ambient water temperature is 10 degF. The tubing is vertical and has a 2.0-inch I.D. and there is no gas lift. The wells initial static pressure is that of the reservoir BJA1. Well 2: Mid perfs at 4000ft below sea level, producing the reservoir mixture as a product. Completion is a simple gas PI of 0.003 mmscf/d/psi2. Temperature is the reservoir temperature while ambient water temperature is 10 degF. The tubing is vertical and has a 2.0-inch I.D. and there is no gas lift. The wells initial static pressure is that of the reservoir BJA1. Well 3: Mid perfs at 4100ft below sea level, producing the reservoir mixture as a product. Completion is a simple gas PI of 0.0025 mmscf/d/psi2. Temperature is the reservoir temperature while ambient water temperature is 10 degF. The tubing is vertical and has a 2.0-inch I.D. and there is no gas lift. The wells initial static pressure is that of the reservoir BJA1. The simulation is to be run for 720 days in 60-day steps for the 360 days and 180 steps for the second year. Initially wells 1 and 3 are open, well 2 being turned on 60 days later. Ambient temperature for the field is 60 degF. All the wells in the Network model should have no BLOCKS on them. Use the Restart facility in FPT (Advanced options) to speed up the simulation.

PIPESIM

Chapter 5: Case Studies - 49 -

The client requires oil and gas phasic flowrates (only) for all the sources and sinks at every timestep in the output file and also that the temperature at the seabed manifold also is available for plotting but should NOT be put in the main output file. Check your results with the plot below:

Training Exercise 1 Licensed to: Neil (BJA) (K-0001)PIPESIM Plot Dec 22 1998

PIPESIM for Windows Baker Jardine & Associates, London

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5.1.2 Exercise 2: Produce a Custom Summary File that can be used to generate a look-up table.

Exercise 1 illustrated the building of compositional gas tank model. You will now take the results from that model and produce a look-up table that can be used to re-run the model but this time in look-up table mode. Follow the instructions below: The first step is to produce a custom summary file from the post-processor containing the information relating to the depletion characteristics of the compositional tank reservoir BJA1. So select the postprocessor and click on the Tanks radio button. Then select BJA1 in the list box. The next step is to customise this view so that it displays the inventory of gas, and the pressure of the reservoir in the same column. To do this, click on Customise to access the customise output dialog. Select Tanks and a custom summary number from 1 to 6. Then remove any existing output from the right hand list box. Now select HCIP gas and pressure from the first window. Click on OK and go back to the main

Revision B FPT

window. Click on BJA1 again and you should see the start of a look-up table (two columns of data, HCIP gas vs. pressure). The next step is to write this data out to the custom summary file where it can be manipulated using a spreadsheet to produce a table suitable for use as a look-up table decline curve. So click on Update CSF from the post-processor dialog. You will then be asked Do you wish to Append this data? to what is already in the custom summary file. You dont at the moment so click on No. Now press Edit CSF and a text editor should start up with an image of what was just in the postprocessor window. You now need to load a spreadsheet such as Excel and load in this .CSF file, using the Wizard to select a space delimited file. Look-up tables need a cumulative production column and a static pressure column. You have a reservoir inventory column and a static pressure column so use the spreadsheet to manipulate these numbers into the required format and then save the file in the model directory as a Text file with the name BJA2.TBL Go back to FPT and Use the Mode menu item to select look-up tables and then bring up the reservoir editor. Select an UNUSED table (all of them are likely to be unused at present) and use the leftmost list box to select Cumulative gas and Pressure as your column headings. Save this file using with the name BJA1.TBL and then select Edit. You now need to use the text editors to copy the numbers from BJA2.TBL into BJA1.TBL between the TABLEDATA keywords. Save the text files from the editors and then close the text editors. Back in FPT, LOAD the table into the table file and the data obtained from the TANK model reservoir should appear in the columns. You can now map this look-up table to the Network wells in the same way as you did for the tanks and run the simulation again with a different name. Check your results from this simulation with the plot below. If all is well you should now have a good understanding of how look-up tables work and the relationship between tanks and tables.

PIPESIM

Chapter 5: Case Studies - 51 -

Training Exercise 2 Licensed to: Neil (BJA) (K-0001)PIPESIM Plot Dec 22 1998

PIPESIM for Windows Baker Jardine & Associates, London

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5.1.3 Exercise 3: More complicated EVENT logic and flowrate constraining wells.

You now have a good understanding of how to set up reservoir models and link them to the surface Network and also how to customise and manipulate the output. Now, the wells are going to be choked back if necessary so that they can produce up to a maximum flowrate. Also, well 2 is only going to be turned on if the production at the FPSO drops below a given value. In your look-up table model from Exercise 2, select the Initial Flowrate Constraints option from the toolbar or menu and select all the wells, BUT NOT the SINK as indicated by the negative model index number. Now choose GAS RATE from the list box, and type in a rate of 11 mmscf/d in the box below. Select Apply and this flowrate constraint will be imposed upon all of the wells. Click on OK to leave this dialog. Network controls the maximum flowrate from the well by choking the well back. It therefore MUST HAVE a choke to operate in the well description in the Network model. So select the Network models dialog and Edit your Network model. Add a CHOKE to each of the wells at the wellhead. Exit the Network graphical interface again.

Revision B FPT

Now, well 2 is only going to be turned on if the gas production rate at the FPSO drops below 21.5 mmscf/day, so select the Event Editor dialog and delete the event that currently turns on the well after 90 days. Now add an Event that effectively says Turn ON well 2 when the gas production rate at the sink drops below 21.5 mmscf/day. Add this to the events list and then click on OK. Run this simulation using a different FPT model name and then compare your plotted source flowrate results with those provided below:

Training Exercise 3 Licensed to: Neil (BJA) (K-0001)PIPESIM Plot Dec 22 1998

PIPESIM for Windows Baker Jardine & Associates, London

0 100 200 300 400 500 600 700 8000

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PIPESIM

Appendix A: Reservoir Dynamics - 53 -

Appendix A: Reservoir Dynamics

A1: Volume Depletion Reservoirs There is assumed to be no change in the reservoir volume occupied by hydrocarbons during depletion of the reservoir. The material balance equation, expressed at standard conditions for a given volume of production Gp and consequent drop in the average reservoir pressure is given by [Dake - 1978] p p pi= Production = Gas Initially in Place - Un-produced Gas (sc) (sc) (sc) or G G G

EEp

i

= (3.1) where: Gp is the cumulative production expressed at standard conditions G is the gas initially in place at standard conditions E is the gas expansion factor after cumulative production Gp Ei is the gas expansion factor at initially undepleted reservoir conditions For fields units at standard conditions of p=14.17psia, T=520R and Z=1 E p

ZT= 35 37. (3.2)

and by using the equation of state for a real gas pV = ZnRT (3.3) we can re-write equation (3.1) as

pZ

pZ

GG

i

i

p= 1 (3.4)

The initial conditions pi, Zi and G are input from the user Gp can be calculated from the flow rate calculated by Network and flowing time (time-step) specified. In the case of multiple wells in the tank Gp is simply the sum of the flow rates from wells in that reservoir over flowing time. The p/Z term can now be evaluated and correlations at reservoir pressure for the specified fluid composition can now be used to evaluate pressure for the (constant) reservoir temperature and volume.

Revision B FPT

The model assumes that the well flows at a constant rate between each time-step.

A2: Gas Condensate Reservoirs The dry gas material balance as described above may be used to model gas condensate reservoirs. When the pressure falls below dew point, liquid hydrocarbons are deposited in the reservoir. Since FPT is a fully compositional simulator the new 2-phase z-factor for the reservoir will be automatically calculated.

PIPESIM

PIPESIM Table of Contents 1 INTRODUCTION Dynamic Eclipse link Look-up tables Compositional tank models Summary of Capabilities Summary of current Limitations 2 Program Overview Main Screen

3 The Main Menu Commands File Menu 3.1.1 Open 3.1.2 Save 3.1.3 Save As 3.1.4 Print 3.1.5 Print Preview 3.1.6 Print Setup 3.1.7 Recent models 3.1.8 Exit

Edit Menu 3.1.9 Undo 3.1.10 Cut 3.1.11 Copy 3.1.12 Paste

Mode Menu Build Menu 3.4.1 General 3.4.2 Reservoir 3.4.2.1 Eclipse model reservoir specification 3.4.2.2 Look-up table reservoir specification 3.4.2.2.1 CASE STUDY MODE

3.4.2.3 Compositional Tank model reservoir specification

3.4.3 Select Network model(s) 3.4.4 Well mapping 3.4.4.1 Eclipse model well mapping 3.4.4.2 Look-up table well mapping 3.4.4.3 Compositional Tank model well mapping

3.4.5 Define Events 3.4.6 Flowrate constraints 3.4.7 Select auxiliary properties 3.4.8 Eclipse tolerances 3.4.9 Advanced settings 3.4.10 Customise output 3.4.11 Configurat