INTRODUCTION TOPIPEPHASE

Introduction to PIPEPHASE Workbook

The software described in this document is furnished under a license agreement and may be used only in accordance with the terms of that agreement. Information in this document is subject to change without notice. Simulation Sciences Inc. assumes no liability for any damage to any hardware or software component or any loss of data that may occur as a result of the use of the information contained in this document.

Copyright Notice Copyright 2001 Simulation Sciences Inc. All Rights Reserved. No part of this publication may be copied and/or distributed without the express written permis-sion of Simulation Sciences Inc., 601 Valencia Ave., Brea, CA 92823-6346.

Trademarks PIPEPHASE, NETOPT, TACITE, and SIMSCI are registered marks and/or trademarks of Simulation Sciences Inc.

Windows, Excel, and MS-DOS are registered marks and/or trademarks of Microsoft Corporation.

All other products are trademarks or registered marks of their respective compa-nies.

Printed in the United States of America, July 2001.

Contents

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Exploring the PIPEPHASE Desktop . . . . . . . . . . . . . . . . . 5

Defining the Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Setting the Input Units of Measure . . . . . . . . . . . . . . . . . . 22

Entering Thermodynamic or PVT Data . . . . . . . . . . . . . . 24

Specifying the Global Defaults. . . . . . . . . . . . . . . . . . . . . 31

Building the Flowsheet . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Entering Source and Sink Data. . . . . . . . . . . . . . . . . . . . . 36

Defining Links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Setting up a Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Working with Keyword Input Files. . . . . . . . . . . . . . . . . . 53

Running the Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Viewing the Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Fluid Flow Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Applying PIPEPHASE to Downhole Operations . . . . . . . 87

Executing a Sensitivity (or Nodal) Analysis. . . . . . . . . . . 98

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105Introduction to PIPEPHASE i

Introduction

PIPEPHASE is a steady-state multiphase fluid flow network simulatorused for the rigorous modeling of oil and gas gathering and transporta-tion systems. PIPEPHASE provides integrated solutions to networkproblems. It can perform distinct analyses of individual nodes separatelyand it is also able to incorporate the parameters of interrelated nodes intothe total solution. The applications of PIPEPHASE range from the sensi-tivity analysis of key parameters in a single well, to a multi-year facili-ties planning study for an entire field. This program also combines anefficient multiphase network solution algorithm with modern oil and gasproduction analysis techniques to create a unique field design and plan-ning tool. This is coupled with an extensive physical property databank,and integrated with an intuitive Windows-based user interface.

CalculationEngine

PIPEPHASE technology includes:

n Comprehensive physical properties databank and thermodynamiccapabilities

n Fluid types, such as, blackoil, compositional, liquid, gas, steam, andmultiphase mixtures of gas and liquid

n Link devices: pipes, tubing, compressors, pumps, separators, IPRs

n Well analysis with inflow performance

n Gas lift analysis

n Pipeline sphering

n Sensitivity (nodal) analysis

PIPEPHASE also comes with two add-on modules, NETOPT and TAC-ITE, which can be installed at the same time as PIPEPHASE providedyou have obtained the appropriate security. Contact your sales represen-tative for more information.

NETOPTNETOPT provides you with optimization capabilities that allows you tooptimize network performance by defining specific operating objectiveswhile satisfying both physical and user-imposed constraints. For exam-ple, you can use NETOPT to maximize the oil production from a systemof wells operating under injection-limited gaslift, or minimize capitalcosts for a new pipeline system.Introduction to PIPEPHASE 1

TACITEThe TACITE code, developed by IFP, Elf Aquitaine and TOTAL, is acompositional transient multiphase flow simulation tool, for the designand control of oil and gas production pipelines and wells. The programsimulates the transient behavior of a fluid flowing through a single-linkflow system. The source flowrate and sink pressure are specified as time-dependent boundary conditions.

GraphicalUser

Interface

PIPEPHASE GUI features include:

n A true 32-bit Windows-based application

n Interactive data entry and execution

n Generate graphs, tables, and charts; view in Microsoft Excel

n On-line help with hypertext jumpsn And many more.

This comprehensive range of features enables your company to use onesimulator for all phases of business.

PIPEPHASEEngine/GUI

Relationship

PIPEPHASE was originally designed with an easy-to-use keyword ver-sion, where input information was entered through a text editor. The cur-rently enhanced Graphical User Interface (GUI), however, provides amore user-friendly and interactive environment for data input and flow-sheet construction. Although familiarity with the keyword structure canbe useful in executing and troubleshooting simulations, this class willfocus solely on the GUI for several reasons. The GUI prompts you forthe necessary input data, making it easier for you to see what is missingfrom a particular simulation. Furthermore, the GUI provides a visualdescription of the process, giving you a better feel for the simulation.

Figure 1:PIPEPHASE

ComponentsPIPEPHASE

Graphical User Interface

PIPEPHASE Graphical User

Interface

PIPEPHASEDatabase

PIPEPHASEDatabase

PFE TextEditor

PFE TextEditor

PIPEPHASECalculation

Module

PIPEPHASECalculation

Module

PIPEPHASEKeyword File

PIPEPHASEKeyword File

PIPEPHASERAS

PIPEPHASERAS

PIPEPHASEReport File

PIPEPHASEReport File2 Introduction

Where to Find Additional Help

Documents User manuals are shipped with your copy of PIPEPHASE. A completeset of documents is provided on the CD in the form of .PDF files that aremost conveniently viewed using Adobe Acrobat Reader, supplied on theinstallation CD. If you required additional manuals, contact your salesrepresentative.

Online Help PIPEPHASE comes with online Help, a comprehensive online referencetool that accesses information quickly. In Help, commands, features, anddata fields are explained in easy steps. Answers are available instantly,online, while you work. You can access the electronic contents for Helpby selecting Help/Contents from the menu bar.

TechnicalSupport

PIPEPHASE is backed by the full resources of Simulation Sciences Inc.(SIMSCI), a leader in the process simulation business since 1966. SIM-SCI provides the most thorough service capabilities and advanced pro-cess modeling technologies available to the process industries. SIMSCI'scomprehensive support around the world, allied with its training semi-nars for every user level, is aimed solely at making your use of PIPEP-HASE the most efficient and effective that it can be.

SIMSCI offers technical support for PIPEPHASE for all questions sentby fax, E-mail or regular mail. In North America, call our hotline sup-port at 1-800-SIMSCI1. When contacting Technical Support, pleaseinclude the following in your correspondence:

n Name and company, phone and fax numbers

n Product version number

n Problem description, including any error messages that you receivedand the steps necessary to duplicate the problem

n If you are e-mailing your problem, please include an electronic copyof the .INP or .PP0 and .PP1 files.

n When calling in a request, please have this workbook available andbe near your computer to be able to walk through any difficulties. Introduction to PIPEPHASE 3

About This Workbook

This workbook complements SIMSCI's Introduction to PIPEPHASEtraining course. Since much of the course time is dedicated to hands-onexamples, you will not necessarily go through the document page bypage. The workbook does, however, follow the course sequence and youmay want to jot notes in the margin. We strongly recommend that youread this workbook from cover to cover once and then use it to refreshyour memory later on.

Conventions Before you begin this workbook, you should be aware of several conven-tions. These include:

n Italicized text denotes menu items, dialog box names and fields, andlists. For example, File, Save As..., the Source Data dialog box, andComposition Defined.

n Buttons within dialog boxes are represented as gray-filled boxeswith white overlaid text, such as , , and .

n ... Ellipses indicate items that, when selected, bring up a windoor dialog box, for example, and .

n Text in < > brackets indicates keyboard strokes.

n The , icon indicates a cautionary note or a useful tip.

SIMSCI has made great efforts to ensure that PIPEPHASE is compliantwith Microsoft Windows. As a result, much of what follows will be veryfamiliar to experienced Windows users.

n Click, Highlight or Select: Place the pointer on the item and press theleft mouse button.

n Double-click: Same as click except you press the left mouse buttontwice with only a very short pause between clicks.

n Open: To open a dialog box or object, place the pointer on the objectand click or double-click the mouse.

n Drag: Move the mouse while holding the left button down

OK Status Add ->

Modify... Enter Data...

, Note: Remember to save your work often!4 Introduction

Exploring the PIPEPHASE Desktop

The visual engineering of PIPEPHASE makes building a simulationeasy. Functional colors, menu-graphics and picture icons guide youevery step of the way. On-line references refresh your memory on equa-tions and guidelines. And if you encounter trouble, Help is availablewhen you need it.

LaunchingPIPEPHASE

To initiate a PIPEPHASE session: Click Start on the taskbar, select Programs and then SIMSCI. Click on PIPEPHASE. Click , then choose File from the menu bar.

The File menu is described below.

MainWindow

The PIPEPHASE main window, shown in Figure 2, is your primaryworkspace. This window forms the interface between you and thePIPEPHASE program. This is where you will build and run all your sim-ulations, as well as open files, save the current data, or exit the program.

You will use all the familiar Windows features such as toolbar buttons,menus, dialog boxes, and drop-down lists.

Table 1: File Menu OptionsOption Function

New Initialize a new simulation

Open Open an existing simulation

Import Keyword File Load a keyword input file into PIPEPHASE

Close Close the active simulation

Save/Save As Save the active simulation to a file with the same name, or to a new file

Copy Simulation Create a new simulation as a copy of an existing one

Delete Simulation Delete an existing simulation

Run Run the simulation

Remote Settings Run PIPEPHASE calculations from a UNIX machine

View Output File View the output file in the Programmers File Editor

View Keyword File View the input file in the Programmers File Editor

Print Print the flowsheet drawing or output report

Exit Close the active simulation and exit the program

OK Introduction to PIPEPHASE 5

Figure 2:PIPEPHASE

Main Window

Menu Bar Directly below the title bar of the main PIPEPHASE window you willfind the main menu bar. It gives you easy access to the command menus.

Table 2: PIPEPHASE Main Window ComponentsComponent Description

Title Bar The window title contains the name of the current simulation and view.

Menu Bar All functionality can be accessed through the menus.

Toolbar Shortcut buttons for many commonly used PIPEPHASE operations are provided. These include data entry window buttons and viewing buttons.

Primary Workspace This is where you draw your flowsheet.

Scroll Bars The vertical and horizontal scroll bars enable you to move vertically and horizontally through a window.

Status Bar The bar below the toolbar that gives quick help on the highlighted button.

Control-menu Box The standard Windows control-menu in the top left corner can be used to move, resize or close the application window

Table 3: PIPEPHASE Menu BarMenu Main Functions

File File operations: open, close save, import, etc.

Edit Manipulate links and nodes on the flowsheet

View Specify what appears on the main window

General Add input data - all data can be entered from this menu

Special Features Enter case study and time-stepping data; access to a number of performance curves and program databases

Help Access the on-line help functions6 Exploring the PIPEPHASE Desktop

Many of same commands are available through the buttons on the tool-bar.

Toolbar The toolbar appears just below the menu bar on the main PIPEPHASEwindow. Using the mouse, you can initiate many actions by clicking thebuttons on the toolbar.

Data EntryWindows

PIPEPHASE provides dialog boxes that allow you to enter data in a log-ical manner. Throughout this workbook, you will see examples of dataentry windows. Within these dialog boxes, there are many different typesof data entry devices including check boxes, radio buttons, drop-downlists, and buttons.

Table 4: PIPEPHASE Toolbar ButtonsButton Description Button Description

Create a new simulation

Define hydrates

Open an existing simulation

Select units of measurement

Import a keyword input file

Select the components

Save the active simulation

Select thermodynamic method or enter PVT data

Run the simulation and review the results

Set the calculation method

View the output file

Enter the global defaults

Print the output file or flowsheet

Define network optimization data

Add a source to the flowsheet

Zoom in on a selected area

Add a sink to the flowsheet

Zoom out

Add a junction to the flowsheet

Display the entire flowsheet in the main window

Add a calculator to the flowsheet Refresh the flowsheet drawing

Table 5: Data Entry Window ButtonsButton Description

All data are saved and the dialog box is closed.

All data entered or modified are lost when the dialog box closes.

Displays the online help for the dialog box.

OK

Cancel

Help Introduction to PIPEPHASE 7

Color Cues PIPEPHASE uses color cues to inform you of the status of your simula-tion. The significance of the colors you will encounter while workingwith PIPEPHASE are summarized below.

Editing andViewing the

Flowsheet

You can use the options on the Edit menu to modify the placement ofobjects on your flowsheet diagram.

You can use the options on the View menu to modify the data displayedon your flowsheet diagram.

Table 6: Color Significance During Data EntryColor Significance

Red Required data is missing

Blue All necessary data has been entered

Green An item is selected

Gray Data field is not available to you

Table 7: Edit Menu OptionsOption Function

Copy Node... Copy an existing node to a new node at coordinates X, Y

Copy Link... Copy an existing link to a new link

Edit Node... Sort, edit, delete, and copy existing nodes or add a new node to the flowsheet

Edit Link... Sort, edit, delete, copy, or change the flow direction of existing links

Move Node... Move the highlighted node around the flowsheet using the arrow keys

Draw... Add text, a line, a rectangle, or an oval to the flowsheet.

Table 8: View Menu OptionsOption When the option has a checkmark beside it:

View Output View node results or link plots; you cannot make data entries or edits in this mode

Node Labels Node labels are shown on the PFD; for example, S001, D002

Link Labels Link names are shown on the PFD, for example, L001, L002

Show Pressures Defined pressures (not estimates) are displayed on the PFD

Show Temperatures Supplied temperatures for each source are displayed on the PFD

Show Rates Defined flowrates (not estimates) are displayed on the PFD

Ribbon Bar Toolbar is visible below the menu bar8 Exploring the PIPEPHASE Desktop

Link DeviceData Window

The Link Device Data window, shown in Figure 3, is the workspace intowhich you add and define your link data for each link on the main win-dow. To open this window, double-click on any link on the flowsheet.

Figure 3:Link Device Window

This window is broken up into four sections. Starting from the top left-hand-side, these include:

n Access buttonsenter and exit link device view, and open onlinehelp.

n Edit link functionsedit, delete, reverse, copy and paste functions.

n Calculation dataenter link data, nodal analysis data, line sizing data,or TACITE transient data.

n Devices paletteuse this toolbar to add devices to the active link; thedescription for each unit is provided in the status line above the tool-bar, for example, Pipe.Introduction to PIPEPHASE 9

Defining the Simulation

This chapter describes the objectives, applications, and capabilities ofPIPEPHASE. It introduces the concepts involved in pipeline, well, andnetwork analysis and describes how PIPEPHASE tackles them. Thenumerous simulation and fluid types available in PIPEPHASE are alsodiscussed.

Applications The broad applications of PIPEPHASE can be categorized into threeparts:

n Single pipeline analysis

n Wellbore analysis

n Field wide studies

Single PipeAnalysis

PIPEPHASE is a sophisticated tool for the design and analysis of single-phase and multiphase pipelines. The main features of PIPEPHASEinvolve capacity calculations, condensate drop-out problems, CO 2/Steam/N2 injection networks, and heated oil pipelines. The rigorousenergy balance and detailed heat transfer model enable the accurate sim-ulation of viscous fluids in insulated and/or heated oil pipelines as wellas steam injection systems. Capacity calculations form the core of any preliminary process design.PIPEPHASE allows you to specify the desired parameters in a particularfield, and accurately calculates the operating conditions necessary toaccommodate these values. For instance, as a simple example, if one isgiven a specified inlet and a desired outlet pressure at a given flow rate,PIPEPHASE calculates the pump power needed to meet these specifica-tions. You could also use line sizing to vary the diameter of the pipesused in order to provide an optimal estimate for the size of the pipes.

Figure 4:Capacity Calculations

PIPEPHASE also accurately predicts retrograde condensation, or con-densate drop-out problems, in wet gas pipelines. The retrograde phe-nomena is graphically illustrated in Figure 5. Conventional techniquesthat employ extrapolation to predict the point of retrograde phenomenaare invariably incorrect. PIPEPHASE applies a point-by-point PVT anal-

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ysis, which has proven to be extremely accurate. This is especially usefulwhen exact solutions are desired.

Figure 5:Phase Envelope

Steam Injection NetworksIn steam injection networks, PIPEPHASE allows you to develop operat-ing conditions that will minimize heat loss in the network and optimizeenergy usage. Large networks require an optimal distribution of heat formaximum energy efficiency. For instance, an even distribution of steaminjection throughout the network may not necessarily be the optimalarrangement. Such a configuration may exceed heating requirements insome wells and may fail to provide sufficient energy in others.

PIPEPHASE performs rigorous heat transfer calculations to fullydescribe the energy requirements of each individual well, as well as thenetwork as a whole. Because PIPEPHASE performs a rigorous enthalpybalance, it can be used for single component fluids other than steam.

In the example shown in Figure 6, given 600 psia steam at the inlet,PIPEPHASE can calculate the flowing bottomhole pressure.

Figure 6:Steam Injection

Networks

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Heated Oil PipelinesFor heated oil pipelines, PIPEPHASE allows for the variation of nodeparameters (i.e., insulation thickness, heaters, pumps) to meet the pipespecifications. Viscosity characteristics are always taken into account,and the flow characteristics of the fluid can be analyzed exactly. PIPEP-HASE can perform accurate calculations in both laminar and turbulentflow regions, as well as analyze the transition region with equal preci-sion. In the event of sludge formation, especially in heated oil pipelines,PIPEPHASE employs a sphering or pigging model to estimate slug char-acteristics for the design of downstream slug catchers.

WellboreAnalysis

PIPEPHASE provides a comprehensive set of features for the detaileddesign of production or injection well systems. This includes detailedreservoir inflow performance characterization, a choice of completionmodels at the sandface, wellbore geometry variations to accommodatetypical production, injection or artificial lift (ESP or gaslift) operations,and surface flowline and facilities models simulating most oil field oper-ations. Almost all of the well-known mulitiphase correlations, bothempirical as well as mechanistic, are available for a wide range of flow-ing conditions and inclination angles.

Figure 7:Wellbore Analysis

The most common application of PIPEPHASE to wellbore problems is anodal analysis. PIPEPHASE is equipped with a sensitivity analysis fea-ture, which is a generalized nodal analysis tool. This feature can providegraphical solutions to wellbore problems, where the solution node can beany point along the production string, and the inflow and outflow curvescan represent composite multiple parameter behavior. For instance, inmodeling a particular well, the inflow and outflow curves can be givenby the Productivity Index IPR (inflow) and the tubinghead pressure (out-flow). The intersection of these curves provides the solution.

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12 Defining the Simulation

Performance AnalysisFigure 8 illustrates a graphical solution to wellbore calculations. In thiscase, reservoir performance is given (flowing bottomhole pressure as afunction of flow rate). The composite variable in this case is the size(inside diameter) of the pipes. These curves are superimposed on thegraph, and the intersection of these curves with the Reservoir Perfor-mance curve indicates the solution for each case. The solution gives theoperating conditions for the node to meet the desired specifications.

Figure 8:Wellbore Calculations- Varying Pipe Sizes

Figure 9 is analogous to the previous example with a different variable.Instead of varying pipe sizes, you vary well-head pressure (WHP). Also,reservoir performance is represented by two curves, illustrating thedecline in the reservoir pressure with production. Similarly, solutions areindicated by the intersection of the two plots, and the solutions give theoperating conditions needed for the given specifications.

Figure 9:Wellbore Analysis -Varying Well-head

Pressure

PIPEPHASE also models artificial lift methods. The two methods avail-able to the program are continuous gas lift for enhanced fluid recoveryand electrical submersible pump analyses.

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Gas Lift AnalysisIn a gaslift analysis, separator gas available from the oil well or from anoutside source can be used to increase production. The production fluidis considered to be in the tubing and the lift gas in the annulus around it.Using PIPEPHASE, you can investigate the feasibility of injecting gasfor continuous gaslift. PIPEPHASE has four gaslift options:

n With specified oil production and lift gas rate, PIPEPHASE gener-ates pressure profiles in the production and injection strings of thewell.

n With specified tubinghead pressure, PIPEPHASE generates table ofoil production rate vs. specified lift gas rate.

n With a specified range of gas injection valve locations for fixed oilproduction and lift gas injection rates, PIPEPHASE calculates corre-sponding production string pressure, and determines the injectionlocation which is closest to the target outlet pressure.

n With a specified range of gas injection valve locations for fixed oilproduction and lift gas injection rates, PIPEPHASE calculates corre-sponding injection string pressures and determines the locationwhich is closest to the target outlet pressure.

Figure 10:Gas Lift Analysis

PIPEPHASE offers you great flexibility in cases of gaslift analysis. Youcan analyze the performance of wells currently on gaslift, maximize oilrecovery using new gaslift, and determine which gaslift valves should beactivated for a specified production scheme. This allows you to studyeach production well in a field over the life of the reservoir. You can alsodetermine which wells are candidates for gaslift, how production can beimproved with gaslift, and which gaslift rates and valve locations arerequired. Once the performance of an individual well is refined using thegaslift options, the performance of an entire gathering system can be

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analyzed in the network mode with the injection depth and rate specifiedfor each well.

The most common calculation in gas lift problems is the calculation ofthe optimum gas injection rate. Usually, you are given the followingparameters: reservoir pressure, well-head pressure, formation gas-oilratio, and water cut. Injection pressure and gaslift valve locations areusually fixed, and from this information, you must determine the opti-mum lift gas injection rate, Q.PIPEPHASE can generate plots of the liquid and oil production versusgas injection rate, as shown in Figure 11, to indicate the optimum gasinjection rate required (trial injection rates are used as input to this simu-lation to generate the desired graph).

Figure 11:Finding the Optimum

Gas Injection Rate

PIPEPHASE also performs rigorous wellbore heat transfer calculations.These are especially useful in steam injection networks with viscous oil(API < 10, or viscosity > 100 cP). As described previously, the object ofsteam injection networks is to minimize heat loss, and PIPEPHASEtakes into account all the necessary parameters to build an accuratemodel. PIPEPHASE allows user-defined input as well as default valuesfor pipe insulation, heat conduction, convection, heat transfer coeffi-cients, and radiation. It also accounts for time-dependent effects throughthe Ramey function.

Field WideSimulation

The network simulation capability in PIPEPHASE can be used to modelthe interaction between the various elements of a complete oil or gasfield, including all of the wells, gathering and injection lines, surfacefacilities, and contract delivery points. PIPEPHASE also allows thegrouping of production from the same zones for simulating time-depen-dent reservoir pressure decline, and changing well production conditions(increasing GOR and water cut). These capabilities have been linkedwith the ability to simulate production contracts and changing facilitiesto create a field planning tool.

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Region 3: Mist Flow Region. The gas phase is continuous and the bulk of theliquid is entrained as droplets in the gas phase. The pipe wall is coatedwith a liquid film, but the gas phase predominantly controls the pressuregradient.

Transition Region. The change from a continuous liquid phase to a continu-ous gas phase occurs. The gas bubbles may join and liquid may beentrained in the bubbles. The gas phase effects are predominant, thoughliquid effects are also significant.

Ansari Flow Pattern MapThe Ansari correlation is also available in PIPEPHASE for modelingupward two-phase flow. In 1988, A.M. Ansari developed a comprehen-sive model composed of a sub-model for flow-pattern prediction and aset of independent mechanistic models for predicting flow characteris-tics such as holdup and pressure drop in bubble, slug, and annular flow.

The first step in this analysis is the development or prediction of flopatterns. Based on the work of Barnea, Taitel, et.al., Ansari predicteddifferent flow patterns by defining transition boundaries among bubble,slug, and annular flows. This Ansari Flow Pattern Map is shown in Fig-ure 48.

Figure 48:Ansari Flow Pattern

Map

Boundary A shows the transition from Bubble to Dispersed Bubble flowwhich occurs at high liquid rates. In this transition, turbulent forcesbreak large gas bubbles down into small ones.

Boundary B shows the transition from Bubble to Slug flow, which ischaracterized by the coalescence of small gas bubbles into large Taylorbubbles.

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Applying PIPEPHASE to Downhole Operations

PIPEPHASEs downhole capabilities include the following applications:

n Gas Lift Analysis

n Electrical Submersible Pump (ESP)n Time Dependent Production Planning

Gas lift analysis is used to investigate the effects of lift gas on well pro-duction. Another common method of artificial lift is the electrical sub-mersible pump (ESP) . These pumps improve the productivity of wellswith flow rates ranging from a few hundred barrels to tens of thousandsof barrels per day.

Production planning involves the time-dependent interaction betweenthe producing formation(s), and all of the wells, gathering lines, and sur-face facilities in an oil or gas field, and the impact of this interaction onthe overall development strategy of the operating company. PIPEPHASEsupplies this capability through its time-stepping feature.

Gas LiftAnalysis

ProblemThe bottom hole pressure is too low to support the fluid columnin the well.

RemedyReduce the density of the fluid column by injecting gas into thetubing.

DilemmaGas injection creates additional back pressure which reducesproduction rate.

Reservoir pressure decreases gradually once a field is brought into pro-duction. Often there arise situations where the reservoir pressurebecomes so low that it is insufficient for the well fluids to reach the well-head. In these cases, the pressure in the tubing must be artificiallyboosted, or lifted, to enable the reservoir fluids to reach the surface. Suchprocedures can be performed by using artificial lift methods. Gas lift isone of the more common artificial lift methods used in the petroleumindustry. Other methods include sucker rod pumping, electric submers-ible pumps, and plunger/chamber lift, to name a few.

In gas lift, the object is to introduce gas near the bottom of the tubingstring. This injected gas lightens the fluid between the injection pointand the wellhead. Thus, the available bottom hole pressure becomes suf-ficient to lift this column of aerated fluid to the top. Gas can be injectedIntroduction to PIPEPHASE 87

continuously (continuous gas lift) or in spurts (intermittent gas lift).PIPEPHASE allows you to model a continuous gas lift analysis, inwhich you can specify the fluid properties of the gas, specify valve loca-tions, as well as other parameters.

Figure 53 shows a typical gas lift installation where gas is injected downa packed annulus and oil and gas are produced through the tubing.Although the reverse case is sometimes possible (though very unusual),it is not presently supported by PIPEPHASE.

Figure 53:Gas Lift

In this case, we assume that the static fluid level is somewhere betweenthe topmost valve and the wellhead. Once gas is injected through theannulus, the topmost valve is designed to open first. This lightens thefluid above the topmost valve, causing a reduced pressure on the valvesecond from the top. The second valve then opens, injecting more gasinto the tubing. This process repeats as more and more valves keep open-ing. Once a lower valve opens, the upper valves are normally designed toclose. You will see that the gaslift effects generally increase with depth.Only the bottom most valve allows gas passage into the tubing. This iscalled the operating valve . The valves above this one merely help inbringing the well into production (i.e. unloading the well). They aretherefore called unloading valves. In steady-state operation, PIPEP-HASE can calculate the depth of the operating valve.

Designing aGas LiftSystem

The main problems faced by the engineer in gaslift design include:

n How much gas should be injected?n At what depth should gas be injected?n What is the casing head pressure limit?

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n What is the wellhead pressure required for target flowrate?

n What is the depth of the operating valve?

There are four options in PIPEPHASE for gaslift analysis:

n Generate the pressure profile for afixed oil production and lift gas rate.

n Generate a table of oil production ver-sus lift gas rate for fixed pressures.

n Locate the gas injection valve to matchrequired tubing head pressure.

n Locate the gas injection valve to matchrequired casing head pressure.

This dialog box appears as part of the simulation definition, and there-fore you must enter data into one of these options before continuing onto the next dialog box. You can access these options again anytime byselecting Special Features/Gas Lift... from the menu bar.Gaslift analysis is limited to single link, black oil, continuous gaslift sys-tems. You must follow certain basic rules when setting up gaslift prob-lems, such as:1. PVT data sets must be available for both the produced reservoir fluid

and the injected gas.2. The production string is automatically named PROD and the gas

injection string (annulus) is named GASL. 3. Gas injection rates are user-specified.

Option 1 Pressure ProfileIn Option 1, Pressure Profile, the casing-head pressure and the lift-gasinjection rate are fixed. Given values for these parameters, PIPEPHASEcalculates the pressure profiles in both the annulus and the tubing for thecorresponding production rate.

When specifying a gaslift calculation with this option, PIPEPHASE willprompt you to enter values for the lift gas injection pressure and temper-ature at the casing head, lift gas injection rate, and the vertical depthfrom the well head to the lift gas injection valve. You can also enter thepercent of soluble lift gas which dissolves in the well fluid. This value isdefaulted to 100%, and generally should not change.Introduction to PIPEPHASE 89

Figure 54:Option 1: Pressure

Profile

Since you know the injection rate along the well depth, obtaining theannulus pressure profile is relatively simple. Pressure profile calcula-tions in the tubing are done as follows:1. As oil rate is fixed (calculated from the injection rate), the bottom-

hole flowing pressure is known, then 2. Use formation GOR to calculate the pressure gradient from the bot-

tomhole to the operating valve,3. Use total GOR (formation = injection) to calculate the pressure

traverse from the operating valve to the wellhead.

Option 2 Injection PerformanceIn Option 2, Injection Performance, PIPEPHASE generates a table of oilproduction versus lift gas rate, given fixed values for wellhead pressures,valve depth and the casing-head pressure. When selecting gaslift option2, PIPEPHASE will ask you to further specify the injection rates. Youcan specify up to nine lift gas injection rates in standard gas volumeunits, and all entries must be greater than zero. As in option 1, you canalso enter a value for the percent solubility of the lift gas in the well fluid(generally 100%).

For each gas injection rate, there will be an oil flow rate that satisfies thesystem constraints. At lower gas injection rates, increasing the rate light-ens the well fluid and therefore causes a production increase. However,at higher injection rates, the frictional losses in the tubing may be so highthat this trend is reversed. There is, therefore, an optimal injection rate,as shown in Figure 56.

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Figure 55:Option 2: Injection

Performance

Figure 56:Example Gas

Injection Curve

Note that continuously increasing lift gas rate does not necessarily resultin increased production rate. When frictional forces dominate, higherinjection rates actually decrease production. The optimal gas injectionrate and the corresponding oil production achievable are indicated by thearrows.

Option 3 Valve Location - Fixed Tubing Head Pressure (THP)When you select gaslift option 3, Valve Location - Fixed TH , PIPEP-HASE will prompt you to specify lift gas injection temperature and pres-sure at the casing head, injection rate, and up to eight vertical depthsfrom well head to lift gas injection valves. From these specified values,PIPEPHASE will then locate the gas injection valve to match therequired tubing head pressure. Figure 57 shows a plot of injection depthversus the production string outlet pressure, which you must also spec-ify. Note that greater injection depths process higher wellhead pressures.

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Figure 57:Option 3: Valve

Location -Fixed THP

Option 4 Valve Location - Fixed Casing Head Pressure (CHP)Option 4, Valve Location - Fixed CH , generates a casing head pressureversus gas injection depth curve. PIPEPHASE models valve perfor-mance by using the orifice gas pressure drop equation. Identical tooption 3, PIPEPHASE prompts you to enter values for lift gas injectiontemperature and pressure at the casing head, injection rate, and up toeight vertical depths from well head to lift gas injection valves. Also,you can enter the percent solubility of the lift gas in the well fluid, whichis generally 100%.

Figure 58:Option 4: Valve

Location -Fixed CHP

Gaslift option 4 allows you three additional entries:1. Orifice inside diameters corresponding to the gas-lift injection

valves.2. Inside diameters of tubing above gaslift valves corresponding to the

gas-lift injection valves.

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ElectricalSubmersiblePump (ESP)

Electrical Submersible Pumps(ESPs) are applicable to a widerange of operating conditions: deepformations, high viscosity fluids,directionally-drilled wells, etc. Theprimary limiting factor in the effi-cient operation of an ESP is theamount of associated free gas pro-duced. Free gas (as opposed to gasin solution), which in limited quan-tities actually improves operation(by increasing overall fluid buoy-ancy), also progressively degradesperformance due to cavitation, ulti-mately creating a gas lock, at whichpoint the pump ceases operation. Tprevent such performance degrada-tion, free gas is frequently (par-tially) separated downhole, and re-introduced into the productionstream downstream of the chok(venting to the atmosphere not being permitted in most areas).

The ESP model in PIPEPHASE simulates a downhole pump in terms ofits effects on the hydraulics of the well-bore. This includes logic to han-dle specific features such as gas separation at the inlet (and subsequentre-injection at the surface), and the effect of viscosity on pump perfor-mance.

Clicking the ESP button in the Link Device Data window brings up theElectrical Submersible Pump dialog box, shown in Figure 59. This is theoriginal Pump dialog box with an additional button for the entry of ESP-specific data.

Figure 59:Electrical

Submersible PumpDialog BoxIntroduction to PIPEPHASE 93

There are two categories of data entry under the Electrical SubmersiblePump dialog box. The first category is for data specific to the pump, andthe second for data specific to a downhole separator located immediatelyupstream of the pump (to reduce the gas ingestion). Pump-specific datainclude auxiliary power, submergence depth, casing head pressure, andthe vertical pressure gradient. A check box for the Riling correction fac-tor is provided for viscosity-related corrections to the pump performancecurves. The Head Degradation Curve (maximum of 5 points) allows thespecification of degradation as a function of gas fraction. When a down-hole separator exists, you are prompted for the separator name, andeither the gas ingestion percent (GIP) rate for the pump, or the pump ODand casing ID, to calculate the GIP internally.

Under the Electrical Submersible Pump Curve dialog box, you have achoice of entering up to ten data points or the three constants in each ofthe quadratic equations representing the head, efficiency and horsepowerin terms of the in situ volumetric flow rate.

Time-Stepping

ProductionPlanning

Although PIPEPHASE is a steady-state simulator, it can accuratelymodel well behavior over an extended period of time. Typically, the timeperiod of analysis extends from a few years to the entire producing lifeof the field. For such periods, a quasi-steady-state approach is expectedto be an adequate representation of the time-dependent problem. Thisapproach can be achieved through successive steady-state PIPEPHASEsimulations, each representing a time-step in the operating history of thefield.

The main components of the time-stepping analysis are:

n Well Grouping

n Reservoir Depletion

n Facilities Planning

Well Grouping Each of the well completion zones in a gathering network from a specificformation or reservoir. The decline in the reservoir pressure with timeand the changes in the characteristics of the fluid produced are a functionof the total fluid volume produced form the reservoir. For the purposes ofthese claculations, a well completion is associated with a reservoirgroup. A reservoir group includes all of the producing zones that con-tribute to its depletion.94 Applying PIPEPHASE to Downhole Operations

ReservoirDepletion

The depletion of a reservoir over the life of a field is represented by adecline in average reservoir pressure that affects the production capacityof the associated wells. Additionally, with time, the composition of theproduct fluid changes. For most reservoirs, the gas-oil ratio increaseswith time; for a reservoir with an active water drive, the produced watercut increases as the water table creeps up. The reservoir depletion featurewill predict the average decline in reservoir pressure for all the comple-tions in the reservoir as a function of the cumulative produced volume.In addition, at the end of every time step, it will update the water cut andGOR in each associated completion zone as simplified functions of thecumulative production rate (or reservoir pressure).

Figure 60:Reservoir Pressure

Over Time

In PIPEPHASE, the user-specified data for reservoir depletion includesthe initial cumulative production rate (Qcum) and the basis for Qcum cal-culations. The default value for initial Qcum is zero (virgin field) and thedefault calculation basis is oil (or gas for a gas field).

At every time step, PIPEPHASE calculates Q cum by adding productionfrom all the grouped wells. PIPEPHASE also calculates the change inthe average pressure, Pr, average, for the reservoir. It is important to notethat the initial value of the reservoir is taken to be the value you specifiedin the Source dialog box. Subsequent values of P r are calculated fromPr, average. This is a different case from the time-step calculations forfluid characteristics, water cut and GOR. In these cases, the initial valuesare taken from the initial IPR curves rather than those specified in theSource dialog box.

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WellDepletion

Production RateThe reservoir pressure declines by an amount calculated from thegrouped wells. This affects the IPR equation or the tabular data for theIPR, since the reservoir pressure, Pr, is the common variable in most IPRequations. Figure 61 illustrates the dependence of production rate uponwellhead pressure and reservoir pressure. As the reservoir pressuredeclines, so does cumulative production.

Figure 61:Wellhead Pressure as

a Function ofProduction Rate

Fluid CharacteristicsFor an active water drive reservoir, the water cut, fw, will increase signif-icantly with increasing production. The data for the fw decline curve canbe input in the IPR Decline Data dialog box. However, you must alsospecify an initial value for fw in the input dialog box for the Source node.Therefore, an ambiguity may exist between the IPR calculated value forinitial fw and that entered into the source data. To resolve any discrep-ancy, PIPEPHASE will use the value calculated from the IPR curve.This data is well specific, and therefore, gives a more reliable value thanthat input into the source node, which may be an average value.

Figure 62:Water Cut and GOR

as a Function ofProduction Rate

Similarly, for a Solution Gas Drive Reservoir, the Gas:Oil Ratio (GOR)varies with increasing production. To properly model this time-depen-dent variation, PIPEPHASE uses the values from the IPR decline curve

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(if you have supplied these). Otherwise, PIPEPHASE uses the initialGOR value youve specified in the Source node.

In cases of enhanced oil recovery, PIPEPHASE allows you to specifyadditional parameters to more accurately model the system. In the caseof pressure maintenance in an oil field, an additional well is used toinject fluid (for example, water), into the reservoir to prevent or hinderthe decline of reservoir pressure. The cumulative production thenbecomes a function of the amount of fluid being injected and the physi-cal properties of that fluid.

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injection well production well

If water is injected into an oil reservoir, a given volume of water will nothave the same pressure as an equivalent volume of oil. Therefore,PIPEPHASE allows you to enter a Formation Volume Factor (FVF),which takes into account the fluid properties. The FVF is represented byB in the equation above. PIPEPHASE also allows you to specify a deliv-erability basis for the calculations. The default basis is oil, and this isindicated by the Bo in the denominator within the summation above.

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=Introduction to PIPEPHASE 97

Executing a Sensitivity (or Nodal) Analysis

Sensitivity or Nodal analysis allows you to graphically represent theflow and pressure behavior of wells, pipelines and other single link sys-tems when input parameter(s) are varied over a range of values. The sin-gle link option must be chosen to activate nodal analysis/sensitivityanalysis.

Dividing theLink

The link is divided into two sections at any point on the link. This pointis called the Solution Node which you can specify. The section upstreamof the solution node is called the Inflow Section. The section downstreamof the solution node is called the Outflow Section. Figure 63 shows thesolution node at the wellhead. The well is in the inflow section and thesurface flow line is in the outflow section.

Figure 63:Dividing the Link

Concept

The Inflow Performance curve is the plot of the solution node pressurePSN as the flow rate is varied in the Outflow section keeping the sinkpressure constant. Note that PSN increases with flow rate.

Figure 64:Performance Curves

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For the given link with a fixed source and sink pressure the solution nodepressure calculated in the inflow section must have the same value as thesolution node pressure from the outflow section.

Figure 65:Inflow and Outflow

Definitions

Graphically this is represented by the intersection of the the Inflow andOutflow performance curves. The intersection point represents the solu-tion node pressure and the flow rate that you will get for the link.

Figure 66:Inflow and Outflow

Performance Curves

A family of Inflow curves can be generated for a range of values of anInflow parameter. In this case, the parameter is the source pressure. Afamily of Outflow curves can be generated for a range of values of anOutflow parameter. In this case, the chosen parameter is the sink or out-let pressure. When the families of Inflow and Outflow Curves are over-laid on the same plot we get the plot shown in Figure 67.

When a pair of inflow and outflow curves intersect each intersectionpoint represents the operating flow rate and solution node pressure forthe link for the values of the parameters each curve represents. Forexample, Q1 is the flow rate in the link if the source pressure is 600 psiaand the sink pressure is 100 psia. The pressure at the solution node is P1.

The nodal analysis plot concisely represents the system behavior (P SNand Q) of the link when the Inflow and Outflow (plot) parameters varyover a range of values. This information would be useful for predictingsystem behavior or in making decisions on how to control the system toobtain the desired behavior.

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Figure 67:Demonstrating the

Relevance ofIntersections of

Performance Curves

Terminology Sensitivity ParametersWhen generating a nodal plot you have to select one parameter for eachfamily of Inflow and Outflow curves ( Sensitivity parameter). Typicalchoices of a parameter could be the reservoir pressure for Inflow andflow line ID for Outflow.

You can select up to 5 values for each parameter. This implies up to 5Inflow and 5 Outflow curves may be generated. Up to 5*5 = 25 intersec-tion points may be obtained. The chosen parameters must be from thebase case input data. To generate the curves, up to 10 flowrates may bespecified.

Compound ParameterTypically, we choose one parameter. In PIPEPHASE, several parameterscan be compounded into one parameter. Such a parameter is called acompound paramete . A compound parameter may be the ID of a tubingand its corresponding roughness. It may be a combination of parametersfrom different devices. For example, one set of values of the pumppower, pipe ID and heater duty can be compounded as one compoundparameter value.

In PIPEPHASE the available parameters are divided into 7 categories.Compounding can be done only with parameters belonging to the samecategory. The only exception to this is the source data category and theIPR data which belongs to the structure data category. IPR data can becompounded with source data.

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@Y^-$ @Y^-% @Y^-& 100 Executing a Sensitivity (or Nodal) Analysis

Single LinkCalculations

A solution node can be specified by one of 3 ways:

n Specify the device name. The solution node will be placed at the inlet ofthe device. If it is the first device in the link, the source parameterswill belong to the Inflow section.

n Specify the Source name. The solution node will be at the source. In thiscase no Inflow section (and data) can exist. Similarly, specify theSink name. The solution node will be at the sink. In this case no Out-flow section (and data) can exist.

n Specify Bottom or Sink. In this case the solution node will be located atthe outlet of the last device in the link. The Sink parameters may bein the Outflow section. Note that when you select the Inflow param-eters the parameter must belong to the Inflow section. When youselect the Outflow parameters the parameter must belong to the Out-flow section. It is a common mistake to mix up the flow section andthe choice of parameter.

The structure data input requirements include:

n The source and sink pressures must be specified.

n The source flow rate must be estimated.

Additional plots generated in PIPEPHASE include the solution nodetemperature as a function of flow rate for each Inflow parameter valueand the sink temperature for each Outflow parameter.

To generate a nodal analysis plot you must select an Inflow and an Out-flow parameter and the range of values you want to use for each parame-ter. All the parameters are divided into 7 categories. Compounding ofparameters is allowed within each data category only with the exceptionof source/sink parameters and corresponding new IPR Device parame-ters. These two sets of parameters may be compounded even though thebelong to different categories.

Category 4 above refers to the non-compositional source properties thatcan be defined for Sensitivity Analysis. The Lateral Source (categories 6and 7) refers to a subsidiary feed, such as an injection device, which actsas an additional source to the Main source. Introduction to PIPEPHASE 101

NodalAnalysis

Output

Nodal Analysis output consists of the following:

n The Nodal Pressure plotdisplays the solution node pressure versusflow rate curve for each value of the sensitivity Inflow and Outflowparameter. The plot data is included.

n The Nodal Temperature plotdisplays the solution node temperature ver-sus flow rate curve for each Inflow parameter value and the sinktemperature versus flow rate for each Outflow parameter value. Theplot data is included.

n If completions exist in the simulation, a family of completion pres-sure drop versus flow rate is plotted for each Inflow parameter if thecompletion is in the Inflow section or Outflow parameter if the com-pletion occurs in the Outflow section. The plot data is included.

n The intersection points are reported in the output report.

Figure 68 shows a typical nodal pressure plot. The Inflow parameter issource pressure and the Outflow parameter is pipe ID Increasing sourcepressure increases flow rate and increasing pipe ID increases flow rate.

Table 11: Available ParametersCategor Device Available Parameters

Source Pres, PI, Vogel, Coeff, Exp

Sink Pres, II, Coeff, Exp

Structure Completion Shots, Perforation Diameter, Penetration Depth, Tunnel

Pipe ID, Rough, U, Floweff

Tubing ID, Rough, U, Floweff

Riser ID, Rough, U, Floweff

Annulus ID, Annulus, OD Tube, Rough, U, Floweff

Choke ID, Coeff

Compressor Stages, Power, Pres, Eff

Pump Stages, Power, Pres, Eff

Heater Duty, Tout, DP

Cooler Duty, Tout, DP

Separator Percent, Rate

Injection Temp, Pres

Sales Rate

Glvalve Rate, Dissolve

IPR RVAL

PVT GOR, WCUT, CGR, WGR, Quality

Main Source Compositional Composition

Lateral Source Compositional Composition

Lateral Source Rate, Temp, Pres102 Executing a Sensitivity (or Nodal) Analysis

The nodal plot helps to decide what source pressure and pipe ID combi-nations would be feasible for a desired throughput.

Figure 68:Nodal Pressure Plot

FeaturesUnique to the

PIPEPHASE

PIPEPHASE offers many nodal analysis technical features not com-monly found in standard nodal analysis packages. The compositionalcapability with the extensive SIMSCI component library is one exampleof these features. This allows rigorous simulation of phase behavior andheat transfer that is not possible with black oil type approaches. Otherfluids that can be used include steam, black oil, liquid, gas and gas con-densate models.

PIPEPHASE solves the total energy balance equations. This enables thecalculation of both pressure and temperature profiles in the link. Also,you have the option of conveniently defining the location of the solutionnode. The best choice of the solution node location changes from prob-lem to problem and where field data may be available for comparison.

As you have seen earlier, you can use all standard PIPEPHASE equip-ment devices in the sensitivity analysis. A number of parameters for eachdevice are available for you to vary, in order to fully study the effects ofspecific parameters on the overall system performance. In addition todevices which affect pressure drop, PIPEPHASE allows the study oftemperature change devices (heater/cooler capacity).

The option of combining, or compounding, parameters together is apractical feature which can save considerable simulation time. Severalsensitivity variables can change in unison like a single parameter. Thisfeature also allows you to organize the sensitivity analysis more, whichis especially useful when working with a large number of parameters.

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PIPEPHASE Sensitivity Analysis is structured such that virtually anyoilfield production/injection problem or any pipeline problem can beanalyzed. The fluid composition itself can be changed. You can performa gaslift analysis using the black oil model using the gaslift analysisoption. But the Sensitivity Analysis feature also allows you to carry out acompositional gaslift analysis by using the Injection device. Finally, the nodal analysis can be done in conjunction with PIPE-PHASEs Case Study option. This allows you to vary other parameters,independent of the nodal analysis parameters. This enables you to effi-ciently generate an unlimited number of plots in one simulation run. 104 Executing a Sensitivity (or Nodal) Analysis

Index

A

Algorithm, solution 56

Annulus 43

Ansari flow regime map 80Antoine viscosity data 24

Applicationsfield wide simulation 15single pipe analysis 10wellbore analysis 12

Artificial liftapplications 12gas lift method 14

Assay data 20

B

Blackoil modelfluid type 19PVT data 24

Bottomhole completions 46

Bottomhole pressurecalculating 11

C

Calculation methodsalgorithm 56convergence 59forward traverse 55line sizing 57mass balance method 54pressure balance method 54, 59rules 54segments 55tolerances 58

Calculator 40

Case studychange types 50change variable names 49cumulative changes 50entering data 49functionality 49global changes 50individual changes 50

limitations 49parameter 50running a 52variables 50

Change types 50

Change variable names 49

Check valve 47Choke 48

Color cues 8

Component lumping 62Components

defining 19entering data 38generating from assay data 20library 20lightends data 21petroleum 20

Compositional fluid modeloptions 19phase type 21source 37thermodynamic data 28transport methods 29

Compound parameter 100Compressor 47

Contaminants 24, 25

Convergence, ways to obtain 59Correlations

flow 31flow regime 76fluid properties 18mixing 25oil, water 27pressure loss 75viscosity 25

Cumulative changes, case study 50

D

Data entry windows 7

DefaultsSee Global defaults

Device summary 67Distributed flow 75

Downhole operations

electrical submersible pump 93gas lift analysis 87time-stepping analysis 94

Downward stratified flow 83

DP-DT device 48

Duns and Ros flow regime map 79

E

Edit menu 8

Electrical submersible pump (ESP)applications 93curve data 94data requirements 93

Elevational changeseffect on temperature 85

F

Fetkovichs gas flow equation 45Field wide simulation

applications 15reservoir decline 16

File menu 5

Flash report 67Flow correlation defaults 31

Flow efficiency parameter 32

Flow patternshorizontal 75vertical 79

Flow regime correlations 76

Flow regime mapsAnsari 80Duns and Ros 79Mandhane 77Taitel-Dukler-Barnea 78

Flowsheetediting 8junction 38links 41network types 33sink 39source 36terminology 33viewing 8Introduction to PIPEPHASE 105

Fluid characteristics, reservoir 96Fluid models

blackoil 19compositional 19gas condensate 19non-compositional 18single-phase gas 19single-phase liquid 19steam model 19

Forsheimer equation 45

Forward traverse calculation method 55

Friction factor 72

G

Gas condensate modelfluid type 19PVT data 25

Gas lift analysisdesigning in PIPEPHASE 88injection performance 90modeling 14modeling options 89optimum gas injection rate 15PIPEPHASE options 14pressure profile 89simulation type 17typical installation 88valve device 48valve location - fixed CHP 92valve location - fixed THP 91

Gas modelfluid type 19PVT data 25

Global changes, case study 50

Global defaultsflow correlations 31flow efficiency parameter 32HW coefficient 32inside diameter 32Palmer corrections 31thermal 32transitional Reynolds number 32

H

Heat transfer calculations 11, 15defaults 32effects of temperature 86insulation layers 84large elevational changes 85methods 55

overall U-value 41, 83performing 83pipe 42temperature 84

Heated oil pipelines 12

Heater/cooler 47

Helpdocuments 3online 3technical support 3

Holdup, liquid 73Horizontal flow patterns

distributed flow 75intermittent flow 75segregated flow 75

HW coefficient 32

Hydrates 40

I

Individual changes, case study 50Inflow Performance Relationship (IPR)

Fetkovichs gas flow equation 45modeling 43Productivity Index (PI) model 43solution gas-drive reservoir 45

Injection device 47

Injection performance, option 2 90

Input units of measureSee Units of measure

Inside diameter defaults 32

Insulation 84

Interactive output 64Interactive run capabilities 61

Interconnected wells 16

Intermittent flow 75

J

Jones gravel-packed completion 46Junction

data requirements 38inactivating 36

K

Keyword input filecreating 62data entry order 53importing 5

reprint in output file 66running 62

L

Laminar flow 72

Library components 20Lightends 21

Line sizingentering data 9maximum velocity 57options 57running 62

Linkannulus 43bottomhole completions 46check valve 47choke 48compressor 47definition 41dividing the 98DP-DT 48gas lift valve 48heater/cooler 47injection device 47IPR 43multi-stage compressor 47pipe 42pumps 47regulator 48riser 42separator 47summary 67tubing 43

Link Device Data windowfeatures 9opening 9

Liquid holdupdefining 73no-slip 73

Liquid modelfluid type 19PVT data 26

Looped networks 34

M

Main windowcolor cues 8components 6data entry windows 7menu bar 6106 Index

opening Link Device Data window 9toolbar 7workspace 5

Mandhane flow regime map 77

Maps, flow regimeAnsari 80Duns and Ros 79Mandhane 77Taitel-Dukler-Barnea 78

Mass balance method 54

McLeod open-perforated completion 46Menu

edit 8file 5view 8

Menu bar 6

Multiphase flowdownward stratified flow 83horizontal flow patterns 75liquid holdup 73modeling 72pressure drop 73problems unique to 81sphering (pigging) 58terrain-induced slugging 82vertical flow patterns 79vertical upward flow 81

Multi-stage compressor 47

N

NETOPT 1Network model 17

Networkslooped 34running 62tree 33types 33

New file 5Nodal analysis

application 98calculations 101compound parameter 100dividing the link 98entering data 9features unique to PIPEPHASE 103inflow/outflow curves 98output 102running 62sensitivity parameters 100terminology 100wellbore applications 12

Node summary 67Non-compositional fluid models

define 18source requirements 37

No-slip liquid holdup 73

O

Online help 3

Optimization 1

Optimum gas injection rate 15Output

link profiles 64nodal analysis 102node and link labels 64node simulation results 64

Output format changes 68

Output reportsections 66See Also Reportunits of measure 23

Overall heat transfer coefficient 41, 83

P

Palmer corrections 31Parameters

case study 50compound 100sensitivity 100

Performance curves 98

Petroleum components 20Phase envelope 10

Phase type 21

Pipelines, heated 12PIPEPHASE

applications 10components 2GUI 2launching 5main window 5NETOPT add-on 1simulating networks in 17TACITE add-on 2technology 1window components 6

Pipes 42

Plot viewer 70

Plotscreating in RAS 69

inflow/outflow parameters 102link profiles 64nodal temperature 102pressure vs. distance 65print options 64production vs. gas injection rate 15RAS example 70

Pressure balance method 54, 59

Pressure drop function 73

Pressure loss correlations 75

Pressure profile, option 1 89Print options 64

Production rate 96

Pumps 47PVT data

blackoil model 24condensate gas 25gas fluids 25liquid model 26steam model 27

PVT table generation 17

Q

Quality 37

R

Reference source 36

Regulator 48

Reportdevice summary 67flash 67link summary 67options 68summary 67

Reservoir decline option 16

Reservoir depletion 95

Reservoir performance curve 13Reservoir pressure 96

Reservoir, solution gas-drive 45

Resultslink profiles 64nodal analysis 102node 64

Results Access System (RAS)output format 68plot viewer 70plots 69report options 68Introduction to PIPEPHASE 107

running 67tables 68

Retrograde condensation 10

Reynolds numberlaminar and turbulent flow 72transitional 32

Risers 42Run options

interactively 61run other 63run remote 63

S

Save 5Segments, calculation 55

Segregated flow 75

Sensitivity analysisSee Nodal analysis

Sensitivity parameters 100

Separator 47

Simulationchanging the UOM 22copying and deleting 5creating a new 5defining 17editing 8printing 5running 5saving a 5viewing 8

Simulation typegas lift analysis 17network 17PVT table generation 17

Single pipe analysiscapacity calculations 10heated oil pipelines 12phase envelope 10steam injection networks 11

Single-phase flowacceleration term 72elevation change 71friction loss 71modeling 71

Single-phase gas model 19Single-phase liquid model 19

Sinkinactivating 36requirements 39

Slugging, terrain-induced 82

Solution algorithm 56Source

compositional fluid 37data requirements 36entering component data 38estimated values 36fixed values 36inactivating 36non-compositional 37reference 36temperature requirement 37, 38

Spheringmodeling 57

Start PIPEPHASE 5

Steam injection networks 11Steam model

fluid type 19PVT data 27

T

Tablescreating 68example 69

TACITE 2component lumpring 62entering transient data 9running 62

Taitel-Dukler-Barnea map 78

Technical referenceflow regime correlations 76friction factor 72horizontal flow patterns 75multiphase flow 72multiphase phenomena 81single-phase flow 71vertical flow patterns 79

Technical support 3

Temperature calculations 84

Terrain-induced slugging 82Thermal defaults 32

Thermodynamic datahandling water 29method applications 29options 28pre-defined methods 28transport methods 29

Time-stepping analysiscomponents 94reservoir depletion 95well depletion 96well grouping 94

Tolerances 58Toolbar 7

Transitional Reynolds number 32

Transport methods 29Tree networks 33

Tubing 43

Turbulent flow 72

U

Units of measureoutput 23pre-defined sets 22standard sets 23

UNIX, running PIPEPHASE on 63

V

Valve locationfixed CHP, option 4 92fixed THP, option 3 91

Variables, case studydevice 51pipe 51source and sink 50

Vertical flow patterns 79

Vertical upward flow 81

View menu 8Viscosity correlations 25

W

Water cut 96Water, thermo for handling 29

Well depletionfluid characteristics 96production rate 96

Wellbore analysisgraphical solution 13heat transfer calculations 15nodal analysis 12overview 12varying pipe sizes 13varying well-head pressure 13

Wellsgrouping 94horizontal 46interconnected 16

Workbook conventions 4108 Index

Contents

Black Oil Pipeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Black Oil Flowline with Devices . . . . . . . . . . . . . . . . . . . . 6

Compositional Pipeline. . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Gas Well . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Case Study of Black Oil Pipeline . . . . . . . . . . . . . . . . . . . 22

Heavy Crude Pipeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Pipeline Sphering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Looped Black Oil Network. . . . . . . . . . . . . . . . . . . . . . . . 37

Black Oil Gathering System . . . . . . . . . . . . . . . . . . . . . . . 40

Two Well Gas Lift Analysis . . . . . . . . . . . . . . . . . . . . . . . 44

Steam Injection Well. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Forecasting Well Production . . . . . . . . . . . . . . . . . . . . . . . 55

Three-Year Decline Model . . . . . . . . . . . . . . . . . . . . . . . . 59

Ridge Pipeline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Appendix - Keyword Input Files . . . . . . . . . . . . . . . . . . . 73

All diameters in the example problems are in actual mea-surement unless otherwise stated.Introduction to PIPEPHASE i

Black Oil Pipeline

#### TASK Black oil flows through a pipeline with an inner diameter of 10 inchesand a pipe roughness of 0.002 inches. The pipeline drops 1,000 feet overits 20,000 foot length. The fluid properties at the source are listed inTable 1.

Figure 1:Black Oil Pipeline

Part A Create a new simulation BLKOIL. The SOURCE pressure is 1000 psig andthe SINK pressure is 500 psig. Use 100000 bbl/day as the initial flowrateestimate for both the source and the sink.

For these conditions, what is the oil flowrate?

What is the water flowrate?

Part B In a second run, keep the source pressure at 1000 psig, but use a fixedflowrate of 100,000 bbl/day of oil. As for initial sink estimates, use100,000 bbl/day for flowrate and 500 psig for pressure. Note that forblackoil problems, the source flowrate is based on the oil flowrate, notthe total flowrate.

What will the sink pressure be?

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Table 1: Source Fluid PropertiesProperty Value

Oil, API 30

Gas, specific gravity 0.75

Water, specific gravity 1.05

Temperature 120F

Gas/Oil ratio 200 ft3/bbl

Water Cut 10%Introduction to PIPEPHASE 1

@@@@ SOLUTION

Part A Begin by launching PIPEPHASE (double-click the PIPEPHASE icon orselect PIPEPHASE from the SIMSCI folder on the Start menu).

Step 1 Create a New Simulation

Select New from the File menu or click the New button on the tool-bar. The New File dialog box appears.

Name the simulation BLKOIL and click to save your data.

Step 2 Enter Simulation DescriptionThe Simulation Description dialog box appears.

Enter the Problem, Site, and User information along with the prob-lem description in this dialog box.

These entries are optional and you can access this dialog box later byselecting Simulation Description from the General menu.

Click to save your data and exit this dialog box.

Step 3 Enter the Simulation Definition and Input DimensionsThe Simulation Definition dialog box appears. Network Model is thedefault Simulation Type and Blackoil is the default Fluid Type, which areappropriate for this problem. Later, you can access this dialog box byselecting Simulation Definition from the General menu. Click to accept the default definitions.

The Input Dimensions dialog box appears, showing Petroleum as thedefault dimension set. These defaults are acceptable for this problem.

Click to accept the default dimensions.

You can access this dialog box later by selecting Input Units of Measurfrom the General menu, or by clicking the Input Dimensions button onthe toolbar.

Step 4 Enter PVT DataThe Fluid Property Data dialog box appears.

Click to enter the Blackoil fluid properties in the BlackoilPVT Data dialog box.

Fill in the Oil API Gravit , and the Gas and Water specific sravitydata.

OK

OK

OK

OK

New... 2 Black Oil Pipeline

Click to save entries. Click again to exit to the flowsheet.

You can make edits to the PVT data at any time by selecting PVT Datafrom the General menu or by clicking the PVT button on the toolbar.

Step 5 Build the Flowsheet

Build the flowsheet by clicking the source toolbar button and thenclicking again to position the unit on the flowsheet.

Do the same for the sink unit. Select the source unit by clicking on the icon once. A red square

appears on the node and the border of the node turns green to indi-cate that the node has been selected.

Connect the source and sink units by clicking inside this square and,while holding the mouse button down, drag the cursor towards thesink and release.

Step 6 Enter Unit Data

Source Data

Double-click the SOURCE unit on the flowsheet to open the Black OilSource dialog box.

Fill in the Pressure, Temperature, GOR, and Water Cut data fromTable 1.

Enter an initial estimate for the oil flowrate. By default, the OilFlowrate Estimated radio button is activated, indicating that PIPE-PHASE will calculate this flowrate.

Click to save the data and close the dialog box.

Sink Data

Double-click on the SINK unit to open the Sink dialog box. Enter the SINK pressure data. Again, by default the flowrate Esti-

mated radio button is activated, indicating that PIPEPHASE will cal-culate this flowrate.

Enter an initial estimate for the oil flowrate at the SINK.

Step 7 Enter Link Data

Double-click on the LINK between the two units to open up the LinkDevice Data window.

Click on the PIPE button in the device palette to add a pipe to the linkand to open the Pipe dialog box for that pipe.

OK OK

OK Introduction to PIPEPHASE 3

Enter the Length, Elevation Change, Inside Diameter, and PipeRoughness data from Table 1.

When complete, click to save the entries and return to the LinkDevice Data window.

Click to save the LINK device data and return to the main flow-sheet.

Step 8 Run the Simulation and View the ResultsWhen data entry is complete, the borders of all the icons and link lineson the flowsheet turn blue. The outlines of the entered device icons in theLink Device Data window turn blue as well. Any selected item is out-lined in green rather than blue. To determine if the data is complete forthat item, click on an empty region of the flowsheet. If the data is notcomplete, the outline will turn red instead of blue. If any item is outlinedin red, double-click on it to enter the remaining data.

Select Run from the File menu or click the Run button on the toolbar.The Run Simulation and View Results dialog box appears.

Click to solve the network. To check your results, select Output File from the Report drop-down

list in the View Reports section of the dialog box and click .

From the Node Summary, you can see that the standard oil flowrate is107,571 bbl/day and the standard water flowrate is 11,952 bbl/day.

To return to the flowsheet, close the editor. To access the output fileagain, select View Output File from the File menu or click the View Out-put File button on the toolbar.

To view the node output on the flowsheet, select View Output fromthe View menu, and double-click on a unit.

The temperature, pressure, and total liquid flowrate (oil + water) for thatnode in Blackoil type simulations is displayed. For example, if you dou-ble-click on the SINK, the dialog box shown in Figure 2 appears.

, Note: Elevation Change is positive for uphill flow and negative fordownhill flow.

OK

OK

Run

View

, Note: Your results may vary slightly due to the initial estimates andthe specified convergence tolerances ( 2 psi for the pressure).4 Black Oil Pipeline

Figure 2:Sink Summary on

Flowsheet

To view Pressure vs. Distance or Temperature vs. Distance plots, selectDevice Detail as Part, and Plots as Part under Print Options from theGeneral menu before running the simulation. After convergence selectView Output from the View menu or double-click on the LINK. Choosethe plot by clicking on one of the buttons in the Link Plot Selection dia-log box that appears.

Part B Under the File menu, choose Save As and save this problem as BLKOILB.To find the SINK pressure with a fixed SOURCE oil flowrate of 100,000bbl/day and a 1,000 psig SOURCE pressure, perform the following tasks: Select the View Output option from the View menu to return to the

edit input mode. Double-click on the SOURCE, activate the Fixed radio button for the

oil flowrate, and enter a value of 100,000 bbl/day. Double-click on the SINK, activate the Estimated radio button for the

pressure, and enter a value of 500 psig, so that the pressure is calcu-lated by PIPEPHASE.

Rerun the simulation and view your results.

From the Node Summary, you will find that the SINK pressure is nowcalculated to be 678 psig. Introduction to PIPEPHASE 5

Black Oil Flowline with Devices

#### TASK The flowrate through an oil well is controlled using a choke at the well-head. For a 1 inch diameter choke, the desired wellhead pressure is 200psig. Because the reservoir is unconsolidated sandstone, a gravel-packedcompletion has been used.

Figure 3:Oil Well

The upper portion of the tubing string is 2.441 inches in diameter. Thelower portion is 1.995 inches in diameter. The reservoir pressure is 3,000psig and the reservoir temperature is 190F. The temperature gradient inthe earth at this location is 2F/100 feet. Assume an average overall heattransfer coefficient (U) of 10.0 Btu/hr-ft2-F.

The gravel-packed completion has a perforated zone 30 feet long, with 8shots/foot. The expected size of the perforations is 0.39 inches in diame-ter and 3 inches deep. Table 2 gives the properties of the reservoir fluid.

Part A Create a new simulation named OILFLW. Use 500 bbl/day as the initialflowrate estimate for both the source and the sink.

For these conditions, what is the oil flowrate?

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Table 2: Reservoir Fluid PropertiesProperty Value

Oil, API 35

Gas, specific gravity 0.71

Water, specific gravity 1.02

Gas/Oil ratio 300 ft3/bbl

Water Cut 20%6 Black Oil Flowline with Devices

Part B A pipeline is proposed to transport the oil from the wellhead to a centralstorage tank. First, all of the gas phase is separated for re-injection intothe reservoir to maintain the pressure. A pump (efficiency = 85%) isused to raise the fluid pressure to 700 psig. The 2.441 inch diameterpipeline to the storage tank is 15,000 feet long with an elevation increaseof 200 feet.

Figure 4:Transportation

Pipeline

As for initial sink estimates, use the value calculated in Part A for flow-rate and supply 200 psig for the sink pressure.

How much gas is being removed at the wellhead?

What is the required horsepower of the pump?

What will the sink pressure be?

@@@@ SOLUTION

Part A Create a new simulation by selecting New from the File menu and namethe simulation OILFLW.

Step 1 Enter Simulation Description

Enter a description in the Simulation Description dialog box.

Step 2 Define the Simulation and Input DimensionsIn the Simulation Definition dialog box, keep Network Model as theSimulation Type and Blackoil as the Fluid Type.

In the Input Dimensions dialog box, keep the units of measure as Petro-leum.

Step 3 Enter PVT DataThe Fluid Property Data dialog box appears next.

Click New to open the Blackoil PVT Data dialog box. Supply the Oil API Gravit , and the Gas and Water specific gravity

data and click .

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OK Introduction to PIPEPHASE 7

Step 4 Build the Flowsheet

Add a source and a sink to the flowsheet. Connect the two with alink.

Step 5 Enter Unit Data

Source Data

Double-click on the SOURCE unit on the flowsheet to open up theBlack Oil Source dialog box.

Using the data provided in Table 2, fill in the fields for source Pres-sure, Temperature, GOR, and Water Cut.

By default, the Oil Flowrate Estimated radio button is activated, indicat-ing that PIPEPHASE will calculate this flowrate.

Provide an initial estimate for the oil flowrate at the SOURCE.

Sink Data

Double-click on the SINK icon to open up the Sink dialog box. Enter the SINK pressure. Again, by default the flowrate Estimated

radio button is activated indicating that PIPEPHASE will calculatethe flowrate.

Enter an initial estimate for the oil flowrate. By default, the OilFlowrate Estimated radio button is activated, indicating that PIPE-PHASE will calculate this flowrate.

Step 6 Enter Link Data

Double-click on the LINK to open up the Link Device Data window. Click on the GRAVEL PACKED COMPLETION button. The Gravel

Packed Completion dialog box appears. Enter the Perforation Interval, Shot Density, Tunnel Length, and Per-

foration Diameter data.For a LINK with multiple sections, the order in which you list the devicesis critical. You must enter the section of tubing farthest from the surface

, Note: No information is given to relate the reservoir conditions to theflowing conditions. If a Productivity Index (PI) or any otherInflow Performance Relationship, IPR, information was given,then P and T at the SOURCE would be the reservoir P and T.With no IPR data, they are the flowing bottomhole pressureand temperature.8 Black Oil Flowline with Devices

first. In this case, the bottom section of the tubing string is entered first.

Click on the TUBING button. The Tubing dialog box appears. Enter the Measured Wireline Depth, True Vertical Depth, and Inside

Diameter data into the appropriate fields.

For the lower section, the measured wireline depth is 8,000 feet (= 4,500+ 3,500); and the true vertical depth is 6,500 feet (= 3,200 + 3,300).

Change the Heat Transfer Method from Default to U-Value. Enterthe average overall heat transfer coefficient and temperature gradientdata.

To enter the upper section of the tubing string, click the TUBING but-ton again. Another Tubing dialog box for the second TUBING devicein the link appears.

Enter the Measured Wireline Depth, True Vertical Depth, and InsideDiameter data of the TUBING section next to the source. This timethe measured wireline depth is 3,500 ft, and the true vertical depth is3,200 ft. Make the necessary changes to the Thermal CalculationsArea.

Add a choke device by clicking the CHOKE button and enter theChoke Diameter.

Click to save the LINK device data and return to the main flow-sheet.

Step 7 Run the Simulation and View the ResultsWhen the data is complete, the outlines of all the icons and link linesturn blue on the flowsheet. If there is an item with a red outline, double-click on it to enter the remaining data. Remember selected icons and linklines are green so you must click away from the flowsheet to see its truestatus.

Select Run from the File menu or click the Run button on the toolbar.The Run Simulation and View Results dialog box appears.

Click to solve the network. To check your results, select Output File from the Report drop-down

list in the View Reports section of the dialog box and click .

, Note: Remember that the Measured Wireline Depth of tubing is thetotal length starting from the surface to the bottom of that tub-ing string, and the True Vertical Depth is the depth from thesurface to the bottom of that tubing string.

OK

Run

View Introduction to PIPEPHASE 9

From the Node Summary, you can see that the standard oil flowrate is2,471 bbl/day, the standard water flowrate is 618 bbl/day, and the stan-dard gas flowrate is 0.7412 MM ft3/day.

To return to the flowsheet, close the editor. To access the output fileagain, select View Output File from the File menu or click the View Out-put File button on the toolbar.

Save your simulation before starting Part B.

Part B Under the File menu, choose Save As and save this problem as OILFLWB.To find the SINK pressure for a fixed SOURCE oil flowrate of 2,471 bbl/day, perform the following tasks:

In the Black Oil Source dialog box, click the Fixed radio button forthe oil flowrate and enter a value 2,471.

In the Sink dialog box, click the Estimated radio button for the SINKpressure. Enter an initial estimate for the oil flowrate.

In the Link Device Data window, click once on the CHOKE device sothat the additional devices are added after it. Add the SEPARATOR,PUMP, and PIPE devices to the LINK and input the supplied data foreach.

Change the Device Detail to Part or Full in the Print Options dialogbox, accessed by selecting Print Options from the General menu.

Rerun the program and view your results.

From the Node Summary, you can see that the SINK pressure is 163 psig.From the Link Device Detail Report, you can see that the amount of gasremoved is 0.670 MM ft3/day and the required pump power is 32.2 hp.10 Black Oil Flowline with Devices

Compositional Pipeline

#### TASK A 24-inch diameter pipeline transports crude oil 200 kilometers, over anelevation increase of 400 meters. The desired sink pressure is 10 bar andthe ambient temperature is 20C.

Figure 5:Crude Oil Pipeline

Use 500,000 kg/hr as the initial flowrate estimate for both the source andthe sink.

Part A Use metric dimensions for everything except the fine length, which is ininches. Set the Print Options for link plots to Full. Table 3 gives the com-position and conditions of the source fluid. Table 4 gives data for thehigher-boiling components.

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Table 3: Source Composition and ConditionsComponent Mole % Component Mole %

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