_RELEASE NOTES VERSION 6.2
®
c i m a n y d e b
OLGA 6.2 Release Notes
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TABLE OF CONTENTS: OLGA 6.2 Release Notes Page 1.
INTRODUCTION
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2.
OVERVIEW OF THE OLGA 6.2 RELEASE
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3.
4.
2.1 Version numbers 4 HIGHLIGHTS FOR OLGA 6.2 5 3.1 OLGA 6 is complete for engineerin engineering g use 5 3.2 Extended compatibility compatibility between functionality 5 3.3 Computation Computational al performance 5 3.4 Second order scheme for mass equations 5 3.5 Improved FEMTherm 6 3.6 Time series in HEATTRANSFE HEATTRANSFER R and AMBIENTDATA 6 3.7 New emulsion viscosity correlations, modified emulsion/dispersion properties and new entrainment entrainm ent correlation 6 3.8 Surface treatment in gas/water flow 7 3.9 New Network Component PHASESPLITNODE PHASESPLIT NODE 7 OTHER CHANGES AND BUG FIXES FOR OLGA 6.2 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14
Numerics Steady state solver Compositional/Inhibitor Compositiona l/Inhibitor tracking Steam / Single Component Component Restart Converter Drilling Hydrate Source Well 12 Controller Process equipment General Input / Output
8 8 8 8 10 11 11 11 11 12 12 13 14 16
5.
MODEL CHANGES BETWEEN OLGA 5 AND OLGA 6 5.1 Oil-water predictions 5.2 Better model consistency in OLGA 6 5.3 The node model 5.4 Simulation of two phase cases 5.5 Controllers 5.6 Separator 5.7 Bundle, Annulus and FEMTherm
20 20 20 21 22 22 23 23
6.
OTHER DIFFERENCES BETWEEN OLGA 5 AND OLGA 6 6.1 Integration 6.2 Wall 6.3 Keywords moved to FA models 6.4 Heat Exchanger 6.5 Source 6.6 Valve 6.7 Heattransfer
24 24 24 24 24 24 25 26
OLGA 6.2 Release Notes
6.8 6.9 6.10 6.11 6.12 6.13 6.14
InitialConditions Output Variables Restart Hydratecheck Pig 28 Drillingfluid Position
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26 26 27 28 28 28
7.
FUNCTIONALITY FUNCTIONA LITY IN OLGA 5 NOT AVAILABLE AVAILABLE IN OLGA 6
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8.
CONVERTING CASES FROM PREVIOUS OLGA VERSIONS CONVERTING 8.1 Converting from OLGA 5 to OLGA 6 8.2 Converting from OLGA 6.1 to OLGA 6.2
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9.
LIMITATIONS 9.1 Limitations in the steady state preprocessor preprocessor
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OLGA 6.2 Release Notes
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1. INTRODUCTION These notes accompany the release of OLGA 6.2 from SPT Group. The notes describe changes in OLGA 6.2 relative to OLGA 6.1 and also the main model changes between OLGA 5 and OLGA 6. The document should be read by all users of the program. The complete program documentation consists of the OLGA Help, OLGA GUI User Manual, Tutorial, Installation Guide and these Release Notes. The changes listed below refer to the previous main release, OLGA 6.1. The program is available on PC‟s with Microsoft Windows operating systems (Windows XP, Windows Vista and Windows 7). Several versions of OLGA may be installed in parallel. Note that you may also run several versions of the engine from one version of the GUI - please refer to the Installation Guide to learn how to configure the GUI for several engines. The customer center provides useful information about frequently asked questions and known issues. The customer center is accessible from www.sptgroup.com. from www.sptgroup.com. Please contact SPT Group if problems or missing functionality are encountered when using OLGA or any of the related tools included in the OLGA software package. E-mail:
[email protected] Telephone: +474500 6389 0400 Fax: +47 6484 Address: SPT SPT Group Norway AS, AS, P.O. Box 113, N-2027 N-2027 Kjeller
OLGA 6.2 Release Notes
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2. OVERVIEW OF THE OLGA 6.2 RELEASE The OLGA 6.2 is an upgrade of the OLGA 6.1 simulation engine. The following modules are now available; Slug Tracking, Inhibitor tracking (MeOH, EtOH and Tracer) and Hydrate Kinetics. Kinetics. The FEMTherm module has been improved. All OLGA 5 modules are available in OLGA 6 except for Matlab Toolbox and the server functionality. In addition some minor functionalities are not covered. This is described in Chapter 7. Differences in OLGA 5 and OLGA 6 are described in Chapter 6. The graphical user interface (GUI) for OLGA 6 is also used for OLGA 5. Controllers, Bundles and Separators are implemented differently in OLGA 6 compared to OLGA 5. This is reflected in the GUI, see The User Manual for GUI for more information.
2.1Version numbers The following table lists the version numbers for all programs installed with OLGA 6.2.: Program/Tool OLGA GUI OLGA simulator
File name OLGA GUI.exe OLGA-6.2.exe
Version number 6.2.0.67232 6.2.0.67289
Geometry Editor Multiphase Toolkit FEMTherm Viewer MudTable OLGA Viewer Rocx engine Rocx GUI
Geometry.exe Multiphase Toolkit.exe FEMThermViewer.exe FEMThermViewer .exe mudtable.exe OlgaViewer.e OlgaViewer.exe xe Rocx.exe RocxGUI.exe
1.6.0 6.1.0.1 1.0.0.1 3.3.9 1.0.0.1 2.0.0.0 3.0.0.0
OLGA 6.2 Release Notes
3. HIGHLIGHTS FOR OLGA 6.2 3.1 OLGA 6 is complete for engineering use
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All OLGA 5 modules except for Matlab Toolbox and the server functionality functionality are available in OLGA 6. The following modules are completed in OLGA 6.2 compared to OLGA 6.1 Slug Tracking Inhibitor Tracking
Hydrate Kinetics
3.2 Extended compatibility between functionality OLGA 6.2 provides extended compatibility between key functionality compared to OLGA 5. The figure below shows the main new combinations.
3.3 Computational performance OLGA 6 is a threaded application, developed for multi core platforms, and may give significant performance boost when run on such systems. Most modules are parallelized, e.g. Compositional Tracking and Slug Tracking.
3.4 Second order scheme for mass equations A second order scheme for mass equations equations is an option which is available for all functionality. It will give more accurate results in simulations where it is important to keep sharp fronts, e.g. for rate changes, slugging and injection of inhibitors.
OLGA 6.2 Release Notes
3.5 Improved FEMTherm This module has been extended with the following functionality: Easy modeling of partially buried pipelines Varying ambient conditions around the cross section Capability to handle phase changing materials Trend / profile plot of temperature in the cross section New custom dialog for FEMTherm in GUI (OLGA-05369)
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3.6 Time series in HEATTRANSFER and AMBIENTDATA A new keyword, TIMESERIES, TIMESERIES, has been implemented. implemented. This keyword can be used to define the variation in time of e.g. ambient temperature. (OLGA-01883)
3.7 New emulsion viscosity correlations, modified emulsion/dispersion properties and new entrainment correlation Viscosity correlations: Three new emulsion viscosity correlations have been implemented. These are Barnea & Mizrahi, Woelflin and Table based model. See the user manual on how to use these. The Multiphase Toolkit has been updated accordingly. Emulsion/dispersion properties: properties: An intermedi ate dispersion dispersi range is0.0) introduced. introdand uced.the Be Between tween a new lower lpoint ower critical wate cut intermediate (FWLOW, defaulton value inversion (givenwater byr INVERSIONWATERFRAC) the flow is assumed to be a water-in-oil dispersion flowing above a free water layer. The degree of mixing of water into oil is predicted by the standard OLGA model, but the maximum fraction of the total water stream that can be mixed into the oil is given by EMAX (default value 1.0): (Volume flow of water in oil)/(Total volume flow of water) ≤ EMAX. Both parameters should be defined under the WATEROPTIONS keyword. Entrainment correlation: A new entrainment entrainment correlation correlation has has been implement implemented. ed. The effects effects are: are:
Reduced under-prediction of water Inconsistencies Inconsistenc ies between gas-oil andholdup gas-water removed Better agreement between steady state and dynamic result results s because backflow is removed Small improvements in total holdups and pressure drops
(OLGA5-02275, OLGA-5213)
OLGA 6.2 Release Notes
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3.8 Surface treatment in gas/water flow In earlier OLGA models, regardless of whether or not there was oil in the pipe, the gas-oil surface tension and oil viscosity were used in determining the wave height (gas-liquid) and the entrainment rates. Using oil properties even if there is no oil, could cause wrong holdup and pressure drop for gas-water two-phase flow. This is now fixed by using water physical properties for calculating gas/water twophase. (OLGA-05673)
3.9 New Network Component PHASESPLITNODE The new network component, PHASESPLITNODE, replaces the OLGA 5
BRANCH key PHASE. The PHASESPLITNODE should be used when modeling finger type slug catchers, and is located under ProcessEquipment on CaseLevel together with SEPARATOR. PHASESPLITNODE has six different terminals GAS, OIL, WATER, LIQUID, DRYGAS and MIXTURE. A FlowPath connected to a DRYGAS terminal will only have gas as inflow etc. When the volume fraction of the connected phase(s) is sufficiently low (0.01), the FlowPath inflow will be as from a NODE. If all the connected terminals are of type MIXTURE, the PHASESPLITNODE is identical to an internal node. (OLGA-03785)
OLGA 6.2 Release Notes
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4. OTHER CHANGES AND BUG FIXES FOR OLGA 6.2 4.1 Numerics Stability Improved numerical stability for pressure driven sources with near zero pressure drop. (OLGA-05878) Stability Improved numerical handling of large water holdup gradient. (OLGA-06264) Run time step again for choke velocities above critical After running a time step the velocities at a valve boundary is compared with the critical velocities calculated by the valve model. If the boundary velocities are larger than the velocities, timeto step is simulated again with a new linearization. the critical velocities are thenthe limited the critical velocities. (OLGA-03394)
4.2 Steady state solver Improved steady state preprocessor for compressor recycle Running the steady state preprocessor with a compressor and open recycle loop
should give correct temperatures. (OLGA-05050) Initial interpolation of TEMPERATURE changed Interpolation of temperature for steady state preprocessor changed SINGLEOPTIONS to not go outside limits set in input. (OLGA-4995)
for
Improved logic for determination of flow-regime in steady-state A bug in bubble-flow bubble-flow made it difficult for the flow to enter slug-regime for some cases with large amount of gas. This been fixed, giving (OLGA-06009) better correspondence between steady-state flow-regime andhas dynamic flow-regime
More visible warning if preprocessor does not converge In addition to giving a notice in the beginning of a simulation if the preprocessor does not converge, the message is now repeated at the very end of the simulation. (OLGA-05719) Pressure driven source It is now possible to run Steady State preprocessor for cases which include a pressure driven source which is closed. (OLGA-05081)
4.3 Compositional/Inhib Compositional/Inhibitor itor tracking Improved pressure dependence of Heavy Oil extension of CSP viscosity model An improved pressure pressure depende dependence nce of Heavy Oil extension extension of CSP viscosity model have been included in the Compositional Tracking library. (OLGA-05836)
OLGA 6.2 Release Notes
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Fixed problem for compositional tracking cases with mostly inhibitor in a section using SIMPLETHREEPHASE flash option For a composition consisting of almost pure MeOH, the simplified three-phase flash option found that a flash could be skipped. A check was implemented ensuring that for total compositions with aqueous components present in more than 99 mol%, a normal simplified flash was carried out. (OLGA5-01585) Fixed problem for compositional tracking cases with mostly inhibitor in a section using FULLTHREEPHASE flash option Using the FULLTHREPHASE flash option with a compositions consisting of almost pure MeOH, compositional tracking library found that the flash could be skipped and moved onto mutual saturation of existing phases. This lead to an infinite loop inside the compositional tracking routines. This has now been fixed (OLGA502015) Fixed bug for the initialization of the composition in the compositional tracking library The initialization of the composition inside the compositional tracking library, found the composition to be only gas when there was oil and gas. This required that VOIDFRACTION wrongly needed to be set to 1. This has been fixed. (OLGA502236) Fixed problem for compositional tracking when only small amounts of gas and oil are present Compositional tracking simulations crashed when the amount of gas and oil was very small. This was fixed by interpreting it as only an aqueous phase. (OLGA502242)
More robust full three-phase flash routines in the compositional tracking library Full three-phase flash in compositional tracking routines exited due to nonconvergence in the full three-phase flash (IER=27). To make these more robust, the maximum number of iterations has been increased. (OLGA5-02248) Updated key descriptions MEG tracking changed to Inhibitor tracking, and source valve changed to Pressure driven source. (OLGA-5037) Problems with high pressure in Compositional Tracking fixed Problems with property tuning made water density huge, influencing the static pressure to drop. The property tuning and property limitations from OLGA 5 are implemented in OLGA. (OLGA-5144) Error in plotted mass transfer (PSI) when OPTIONS COMPOSITIONAL=ON The plotted mass transfer (PSI) was twice the actual value when OPTIONS COMPOSITIONAL=ON was used. There was only a bug in the plotted PSI. The mass transfer in OLGA is not changed. (OLGA-05325) Entrainment/deposition calculation at boundary to pressure node
OLGA 6.2 Release Notes
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The entrainment/deposition models in OLGA 5 and OLGA 6 were different for pressure nodes. OLGA 6.2 now uses the upstream gas fraction as is done in OLGA 5. (OLGA-03373) Default values for inhibitor fraction The inhibitor fractions on the branch inlet and outlet, ININHIBFRACTION and OUTINHIBFRACTION, are given default values 0.0 under INITIALCONDITIONS. (OLGA-05329) Compositional molar volumes for SIMPLETHREEPHASE In some cases we may have used wrong compositional molar volumes for SIMPLETHREEPHASE, which may have effected OLGA simulations. This has now been fixed. (OLGA-05889) Improved handling of components that are introduced into a composition composition Previously OLGA had some problems handling components that were introduced into a composition, for instance MEG from a source that was turned on at some point. The treatment of such issues has been introduced giving a much more physical behaviour in these cases. (OLGA-05890) Fixed normalization for thermal properties for shadow phases OLGA uses so-called shadow phases to simulate properties of phases, which only exist in dynamic flow situations (not at thermodynamic equilibrium equilibrium). ). To get the right thermal properties (H, S and Cp) of the shadow phases, the property routines must be called with normalized composition (mole fractions summing to 1.0). By mistake the thermal properties were calculated using a non-normalized shadow phase composition, which has now been corrected. (OLGA-06574) Phase option water and liquid are now also available for black oil The key PHASE=WATER/LIQUID for keyword SOURCE and NODE can now also be used in combination with the black oil option. In previous versions PHASE=WATER/LIQUID would automatically be converted to PHASE=OIL if the
black oil option was used. A warning was reported to the output file regarding this conversion. (OLGA-4846)
4.4 Steam / Single Component Corrected calculation of the thermal conductivity and viscosity in Single Component Module An error in calculating viscosity and and thermal conductiv conductivity ity for SINGLECOMPONE SINGLECOMPONENT NT has been fixed. This error gave an overestimation the viscosity and conductivity of the gas phase, and an underestimation of the conductivity in the liquid phase. (OLGA5-02237) Initial interpolation of temperature changed for Single Component Interpolation of temperature for steady state preprocessor changed for Single Component to not go outside limits set in keyword SINGLEOPTIONS. (OLGA4995). Fixed problem with drying for Steam
OLGA 6.2 Release Notes
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The mass of water vapor in the gas phase was used to test if there was evaporation. The correct test should use the mass of hydrocarbon in the gas phase. This error resulted in no evaporation if the gas phase was initialized with zero water vapor. (OLGA-5088)
4.5 Restart Improved handling of default values for the RESTART keyword When using the default settings for WRITE under RESTART, the restart file is now properly written at the interval given. (OLGA-04872)
4.6 Converter Input converter extensions The input converter now handles conversion of MODE and MODETIME for controllers. Connections are set up for EXTSIGNCONTROLLER, EXTSETPOINTCONTROLLER, MODECONTROLLER and ACTIVATECONTROLLE ACTIVATE CONTROLLER. R. (OLGA-06204) Improved input file controller conversion from OLGA5 to OLGA6 Calculate Table controller MINSIGNAL/MAXSIGNAL form Y-values in POINT variable. (OLGA-05611)
4.7 Drilling STDFLOWRATE / GOR available for DRILLING It is now possible to specify STDFLOWRATE / GOR when DRILLING is ON. (OLGA-3831) Negative pressure in drilling simulations Negative pressure, and pressures above table limit, are now allowed in drilling simulations. Fluid properties are extrapolated. (OLGA-05613)
Leak for inhibitor and drilling fluid The leak outlet mass fractions and temperature were wrong. The isenthalpic flash is corrected. (OLGA-05314)
Source standard volume flow variables and mud QWSTSOUR, QGSTSOUR and QLSTSOUR now show correct values when drilling mud is injected. (OLGA-06104) Drillingfluid components DRILLINGFLUID components are now available also when inhibitor tracking (MEG/MEOH/ETOH) is on. (OLGA-05671)
4.8 Hydrate Output variable SAREA
OLGA 6.2 Release Notes
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SAREA is now plotted with correct unti; area per volume. (OLGA-05543) Hydrate curves with single point is allowed OLGA does no longer crash when hydrate curves with one single point are used. (OLGA-4608) HYDRATECURVE available in Library The keyword HYDRATECURVE is now available only in Library. Earlier it was also available on Flowpath level. (OLGA-5149) COLUMNHEADER in hydrate files not required Use default values (TEMPERATURE C, COLUMNHEADER not given. (OLGA-5186)
PRESSURE
Pa)
when
4.9 Source Pressure driven source and leak flow equation changed. The subcritical choke flow equation used in pressure driven source and leak have been modified. The inflow momentum is set to zero. This is consistent with OLGA 5. (OLGA-04617)
4.10 Well WAXFRACTION available in WELL WELL WAXFRACTION can now be specified. (OLGA-02920) New keys CGR and WGR in SOURCE, WELL and NODE Added CGR CGR and WGR as input input variables for SOURCE, SOURCE, WELL and and NODE. (OLGA-4972) More variables as time series in WELL It is now possible to specify GORST, HOLES, RESEXT, EXPONENTN and INJECTIVITY as a time series in WELL. (OLGA-4922)
4.11Controller Algebraic controller Controller type Algebraic is implemented as in OLGA 5.(OLGA-05353) Branch variables for controller in OLGA GUI Branch variables are added to controllers. (OLGA-04512 ) ) Time step is reduced before a manual controller setpoint change Too avoid overshooting the time where a setpoint change happens, the time step
is reduced. (OLGA-04264) RANGECHECK and TIMESTEPCONTROL in controllers. Controller BIAS is limited to MINSIGNAL and MAXSIGNAL Added RANGECHECK key to the Manual controller. Added TIMSTEPCONTROL key to Manual, PID, ASC, Cascade, ESD and PSV controllers. The initial output
OLGA 6.2 Release Notes
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from the controllers, BIAS, is limited to MINSIGNAL and MAXSIGNAL. (OLGA05229) SCALER and SWITCH controller Two new controllers are available as network components; SCALERCONTROLLER and SWITCHCONTROLLER. (OLGA-05237) New controller STDCONTROLLER The new controller STDCONTROLLER converts a volumetric volume flow at standard conditions to a mass flow. The controller replaces the OLGA 5 SETPOINTVARIABLE and CONTROLLER REFCONDITION=STD. The calculated mass flow is given in the output terminal (OUTSIG). The input converter will automatically generate a STDCONTROLLER when a *.inp case file is run with OLGA 6. (OLGA-02385) Controller sub key SETPOINTMODE Controller sub key SETPOINTMODE in OLGA 6.1 is removed. Controller MODE as defined in OLGA 5 is implemented in OLGA 6.2. (OLGA-06178, OLGA-6189)) Improved OLGA 5 to OLGA 6 input file conversion Extended input converter to handle connection from a controller output (VARIABLE CONTR) to another controllers measured value. (OLGA-05470) Manual controller Rate of change for CONTROLLER type MANUAL related to MAX and MINSIGNAL rather than 0 and 1. (OLGA-05800) Controller type LinearCombination Controller type LinearCombination is replace by controller type Algebraic. OLGA 6.1 cases need modifications. (OLGA-06727)
4.12 Process equipment Changed heat calculations for pump OLGA does a isentropic flash to calculate the heat added to the fluid. Now this is consistent with OLGA 5. Earlier OLGA 6 assumed incompressible liquid and ideal gas compression. (OLGA-4095) INITOILEVEL and INITWATERLEVEL in the network separator INITOILEVEL and INITWATERLEVEL were not used in the network separator. The initial levels in the separator are now calculated from the given INITOILEVEL and INITWATERLEVEL. (Also when the steady-state preprocessor is used.) Added four new keys to the separator: FEEDNAME, FEEDNAME, FEEDMASSFRACTION, FEEDMASSFRACTION, FEEDMOLEFRACTION and FEEDVOLFRACTION. It is possible to use these keys to specify a composition when COMPOSITIONAL=ON/BLACKOIL. (OLGA05226) Changed static pressure for the oil outlets in separator Static pressure in the oil outlets is calculated as "g * oil_density * (oil_level water_level)". Modified water level due to dispersion of water in oil and oil in water.
OLGA 6.2 Release Notes
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Both the static pressures and the water level is now consistent with OLGA 5. (OLGA-5227) Liquid outlets in separator The oil outlets switch to node mode (not separating) when the oil holdup is less than 0.001. The water outlets switch to node mode (not separating) when the water holdup is less than 0.001. Before both the oil and water outlet switched to node mode when either the oil or water holdup was less than 0.001. (OLGA05284) Compressor files and tab -separation The number of mass flow points and number of speed points given in a compressor file can now be tab-separated. tab-separated. This was not supported earlier. (OLGA05502) Fixed error in calculation of valve throttling OLGA used the hydraulic diameter as pipe diameter, but used the actual pipe area to calculate the valve throttling. The valve opening therefore got to small, and simulations could crash. This is now fixed. (OLGA-5544) Improved stability for Recycle/Bypass with components Improved stability for Pump and Compressor Recycle/Bypass when running with components. (OLGA-04941) Compressor instability Improved compressor flow/pressure differentials at low velocities. Stability at low velocity is therefore improved. (OLGA-05571)
4.13 General Phase changing materials in walls The effect of phase changes has been added to the materials used for walls in OLGA. This can be used to model phase change materials used as insulation in pipe walls. It includes changes in thermal conductivity, heat capacity and the effect of latent heat of fusion. In the MATERIAL keyword, a new TYPE=PCM has been introduced. Also five new keys have been added to be used with this functionality: PHCHMAX - Upper temperature limit for phase change region PHCHMIN - Lower temperature limit for phase change region CONDMULT - Conductivity multiplier below PHCHMIN HCAPMULT - Heat capacity multiplier below PHCHMIN FUSIONMULT - Heat capacity multiplier between PHCHMIN and PHCHMAX used to model latent heat of fusion. (OLGA-05248)
OLGA 6.2 Release Notes
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CORROSION available on Flowpath level CORROSION is now available in each FLOWPATH instead of at Case level. Old OLGA 6 cases must be updated manually. (OLGA-3551) Mixture velocity now available in GUI USTOT is an old output variable, but is now also available in the GUI. (OLGA-4307) TUNING split in TUNING and G, SLUGTUNING A new keyword, SLUGTUNING, SLUGTUNIN is added for the global slug tuning parameters. parameters. The TUNING keyword is moved from Case level FA-models to FlowPath level FA-models. (OLGA-04372) Pressure effect in pipe contraction and expansion Added default default pressure pressure loss/recovery loss/recovery due due to pipe contraction/expansi contraction/expansion. on. (OLGA-04677) Bug fixed in order of GASLIFTTABLES The order of GASLIFTTABLES does no longer influence on the simulation results. (OLGA-4777) Change of the level gradient implementation from channel geometry to pipe geometry for both steady state and dynamic simulation An error in the hydrostatic pressure in three phase flow for the dynamic equation equations s was discovered and fixed. This fix gives more consistent result between steady state and dynamic simulations. However, due to numerical problems in the OLGA scheme the new level gradient term may give more numerical instabilities for shut in simulations. (OLGA-05192) FLUID given with TYPE=COMPLEXFLUID and FULL=YES Added fluid data test when FLUID is given with TYPE=COM TYPE=COMPLEXFLUID PLEXFLUID and FULL=YES. Test for power law (POWERLAW) and yield stress (BINGHAM) data. The simulation will abort if the required fluid data is missing. (OLGA-04958) Pressure drop calculations Improved pressure drop calculations for laminar flow at Reynolds number < 0.1 (OLGA-04982) Consistency between the steady state and dynamic solver OLGA steady state assumes zero velocity at the boundary and consider the acceleration from zero velocity to the velocity at the first section. This is now also implemented for the dynamic solver. (OLGA-05702) Water wall shear stress when no water is present Previously, the water wall shear stress was set equal to the oil wall shear stress if there was no water in a pipe. Now, the value is set equal to zero instead. (OLGA-05731)
OLGA 6.2 Release Notes
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Improved handling of user-termination of batch run Pressing Ctrl-C or closing the batch-run window results in OLGA terminating execution immediately in a controlled fashion. Plot and restart files will not be updated or written. Pressing Ctrl-break will force a display of currently elapsed simulation time, execution will proceed as if not interrupted. (OLGA-05832) Interpolation between laminar and turbulent friction factor Earlier the friction factor has been set to the maximum of the laminar and turbulent friction factor. This could overpredict the pressure drop for e.g. one phase MEG where laminar flow can be present for relatively high Reynold's numbers. In TUNING there is a functionality functionality to set the friction factor as a function function of Re: Laminar for Re lower then RELOW, turbulent for higher than REHIGH, and interpolation between RELOW and REHIGH. The default values for RELOW and REHIGH have now been set to 2300 and 3000, respectively (before the default was -1, that is, that this functionality was not used). Both RELOW and REHIGH must be within 0 and 10000, and (REHIGH-RELOW) must be at least 100. (OLGA06272)
4.14 Input / Output Output and restart written when user terminates interactive simulation from GUI Force TREND/PROFILE/OUTPUT/RESTART write if a simulation is terminated by the user from the GUI. Functionality only available when the case is run (interactively) through the GUI. If the case is run in batch mode, no restart etc. will be written. (OLGA-04578) Standard conditions given in keyword PVT table file are now used STDPRESSURE and STDTEMPERATURE in the PVT table file (keyword format) are the standard pressure and temperature given in PVTsim when creating the file, while GOR, GLR, STDGASDENSITY, STDOILDENSITY, STDWATDENSITY and WC (the two latter only for 3 phase table files) are the properties at this standard condition. These values have not been used in previous OLGA versions, but are now used for input (e.g. GORST in WELL) and output (e.g. QGST - Gas volume flow at standard conditions). This will give more precise results in simulations where e.g. GORST in WELL is used and the table is coarse around the standard conditions (e.g. if the two lowest pressure is 0.1 and 10 bara) since the gas mass fraction is not linear with pressure for such low pressures. A new key STDLIQDENSITY STDLIQDENSITY will be introduced in the next PVTsim version. This gives the standard density of liquid water and hydrocarbons (HC) in the case where a two phase PVT file is generated from a composition with water. STDOILDENSITY is the density for HC only and thus does not contain the necessary information. If the keys are not present (removed manually since always written), linear interpolation between the pressure and temperature points will be used as before. Note that the given standard pressure and temperature will be used for both input and output instead of the default values of 1 atm and 15.56 C. (OLGA5-00772)
OLGA 6.2 Release Notes
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Shear strain rate output variables The output variables SHRHL and SHRWT have been implemented for shear strain rate of oil and water film respectively. (OLGA-05635)
Wrong calculation of output variable MACH The calculation of the output variable MACH is corrected. (OLGA-4765) Plot variables no longer limited to 1.0e-20 Earlier, plot variables have been set equal 1.0e-20 if their absolute value has been less than 1.0e-20. Now the variables get the value 0.0. (OLGA-4805) LSEGMENT warning removed There will be no warning issued when the LSEGMENT sum does not add up to the pipe length (SCR-04812). Fixed the calculation of plot variables MWOIL and MWWAT MWOIL/MWWAT gave only half the expected result earlier, due to bug where the sum was divided by number of fields in the phase. (OLGA-4857) Added input check for WAXDEPOSITION OLGA will return an error message COMPOSITIONAL is not OFF. (OLGA-4939)
if
WAXDEPOSITION=ON
and
Error in plot variable HTK when HINNERMIN is used The value of HTK written to plot files was previously not limited by HINNERMIN. However, the value used in the calculations was limited by HINNERMIN. (OLGA04947) Output from bundles written to standard plot files Temperature, ambient heat transfer coefficient and geometry are now available as variables to be plotted in tpl and ppl files. (OLGA-05269) Shear strain rate output variables The output variables SHRHL and SHRWT has been implemented for shear strain rate of oil and water film, respectively. (OLGA-05636) Case with both tabulated and keyword based fluid files is now supported Previously, when fluid files with tabulated format was read after fluid files of keyword based format, OLGA terminated. (OLGA-04919) Better error message A message with location info (FLOWPATH/PIPE/SE (FLOWPATH/PIPE/SECTION) CTION) is displayed when the simulation is aborted due to P/T outside table values. (OLGA-05870) GASCST, OILCST,WATCST and LIQCST added as output variables These would be the total volume of gas, oil/condensate, water and liquid, respectively, in a branch; converted to standard conditions while accounting for
OLGA 6.2 Release Notes
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any mass transfer between phases from actual to standard conditions. (OLGA-5267) New output variables PSIHL and PSIWT PSIHL and PSIWT give the mass transfer rate (kg/m3/s) of oil and water, respectively, respective ly, from liquid to vapor. They are available available for TREND, PROFILE and OUTPUT. (OLGA-05582) Mixing variable types in trend data If several trend variables of different types, e.g., LIQC and TM, are specified
together under a TRENDDATA key, the simulation will abort and the following error message will be given: "INPUT ERROR in keyword TRENDDATA: Variable type mismatch. Plot variables (LIQC, TM) are not of the same type." (OLGA-04897) Hydratecheck warnings Warnings about the temperature or pressure being outside the "hydrate curve" square only if DEBUG=ON and only the first time it occurs. (OLGA-04898) Viscosity and wall shear stress at t=0 The viscosity and wall shear stress are now plotted for time = 0s. Previously, these have been plotted as 0 at t=0. (OLGA-05639) Improved error message When an output variable is requested for a position in a branch where it is not defined, a more descriptive error message is given. (OLGA-05285) Branch variables with specified positions If branch and variable, e.g., LIQC, is is printed. given together with a position, the position will beaignored an info message (OLGA-05148) Error in plotting for closed boundaries after restart Plotting flow variables for closed boundaries gave nonzero values at restart time. Only a plotting problem. (OLGA-05624) More informative error message for section out of range error. When the case contain references to illegal sections, the error message will indicate which keyword is the problem. (OLGA-05805) Min/max/mean branch variable Added MAXTMBR, MINTMBR, MEANTMBR, MAXPTBR, MINPTBR, MEANPTBR as BRANCH variables (OLGA-04967) Variable TWS now available in Trend plot. (OLGA-05430) Variable TWS HEATEXCHANGER - sub key SECTIONBOUNDARY changed to SECTION Heatexchanger is now placed inside the section and not on the boundary as in OLGA 6.1. OLGA 6.1 cases must be updated manually. An error message will be given. (OLGA5-05480)
OLGA 6.2 Release Notes
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Key DTTIME added to PROFILE keyword Functionality for setting the profile plotting frequency as a function time has been added. (OLGA-06058) Changed names of outputvariables XTSOUR, XTWELL and XTLEAK changed to ZSOUR, ZWELL and ZLEAK CGGLK, CGGWEL and CGGSOU changed to CGGLEAK, CGGWELL and CGGSOUR. These output variables are now named the same in versions OLGA 5.3.4 and OLGA 6.2. ( OLGA-06372) MEG output variables renamed to INHIB All MEG output variables areconverted. now changed INHIBfrom (e.g. MEGMFR is now INHIBMFR). OLGA 5 case are OLGAto6 case previous versions will now get a warning for deprecated keys. (OLGA-06576)
OLGA 6.2 Release Notes
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5. MODEL CHANGES BETWEEN O OLGA LGA 5 AND OLGA 6 This chapter goes into some detail on the changes in OLGA 6 compared to OLGA 5. This chapter concentrates on changes in the underlying models of the simulation engine.
5.1 Oil-water predictions Three momentum equations In OLGA 6 there are three momentum equations. One for the gas field, one for continuous hydrocarbon liquid field and one for continuous water field. The different fields may include dispersions (e.g. water and oil droplets in the gas field). In OLGA 5 there are only two momentum equations; one for the gas field and one for thephases. liquid field with a steady state momentum balance for the slip between the liquid The three momentum equations in OLGA 6 will give different result from OLGA 5 when the individual inertia terms of hydrocarbon liquid and water are important. We have seen this e.g. during heavy slugging in risers where OLGA 6 is leaving more water holdup in the riser than OLGA 5. This behavior is corresponding better
with what is expected. Interfacial level gradient term between oil and water In OLGA 6 there is an interfacial level gradient term between oil and water. This ensures that even in a horizontal pipe the heavier fluid will flow to the bottom of the pipe in a shut-in situation. This is also seen to give somewhat more water content in gas condensate pipelines for low flow rates compared to OLGA 5.
5.2 Better model consistency in OLGA 6 The steady state preprocessor The steady state preprocessor in OLGA 6 includes the effect of interfacial level gradients, giving more consistent results between the preprocessor and running the dynamic simulation to steady state. For gas condensate in long pipelines one may now run the case with steady state preprocessor and get the same result as in the dynamic simulation. In OLGA 5 the level gradient between gas and liquid is only included in the dynamic simulation. The steady state preprocessor in OLGA 6 considers the pressure drop due to acceleration from zero velocity at the boundary to the velocity at the first section, while the steady state preprocessor in OLGA 5 does not. Both the dynamic solver in OLGA 5 and OLGA 6 consider acceleration from zero velocity at the boundary to the velocity at the first section.
OLGA 6.2 Release Notes
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5.3 The node model The NODE model in OLGA 6 differs from OLGA 5. In OLGA 5 the NODE is represented by the first/last section in one of the outgoing/incoming branches, but in OLGA 6 the NODE is a separate self-contained network component whose basic role is to either act as a boundary condition to the flow network or couple together an arbitrary set of flowpaths, both merge and split. The pipes connected to a node receive the masses, temperature, and pressure of the node as the boundary conditions. For separators and phase split node, the masses to the pipe boundaries are adjusted according to which fluid a pipeline receives from the node. For the flow calculations at each of the pipe boundaries connected to the node, the pipe parameters, such as diameter, inclination, roughness, are the same as the internals to the pipe. The model for internal nodes (merge/split nodes) uses more or less the same physics and the numerical methods as the sections in the pipes. Pressure, temperature and masses are calculated. Interphasial mass transfer is included in the node, but entrainment/deposition of liquid droplets are ignored. Volume in node The current implementation of internal nodes require a finite volume in the node. If no volume is specified (or given as less than or equal to zero), a default volume is calculated by OLGA based on the sizes of incoming and outgoing sections:
