olga6 tips & tricks
TRANSCRIPT
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OLGA User Group Meeting
OLGA SupportTips & TricksBeijing, UGM, Oct. 18, 2010
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OLGA support
• Send to [email protected]
• Support Center – access to FAQ, track your support requests
• Requesting user feedback on support
• Check www.sptgroup.com for new minor releases
http://www.sptgroup.com/http://www.sptgroup.com/
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Tips & Tricks
1. What is the main difference between OLGA 6 and OLGA 5 ?
2. What hardware is recommended to achieve maximumperformance with OLGA ?
3. Is OLGA compatible with Windows 7 ?
4. Can OLGA simulate Water Hammer effects ?5. Why does not always the 2 nd order numerical scheme give
more accurate results?
6. Why is AXIALHEAT not included in OLGA 6?
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What is the main difference betweenOLGA 6 and OLGA 5 ?
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What is NOT different inOLGA 6 compared to OLGA 5 ?
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OLGA 6 and OLGA 5 : same concept
• fundamental modeling concept is the same – Flow model – Numerical methods for conservation equations
• Graphical User Interface (GUI) is the same
• Comparisons from cases in OVIP data base and from theSPT functional test repository show that:
OLGA 5 and OLGA 6 will in general give very similar results
both for steady-state and transient simulations
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Conservation equations in OLGA 6
• three momentum equations (gas, oil, water) – effect when individual momentum of oil and water are
important (heavy slugging in risers)• an interfacial level gradient term between oil and water
– give higher water content in gas condensate pipelines for lowflow rates
• better consistency between steady state pre-processor anddynamic solution
– interfacial level gradients included in pre-processor
• 2nd order scheme for mass equations – optional
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OLGA 6 has a new node model
• Internal nodes have a finite volume – use same physical and numerical models as sections
– more general than split/merge => easier to model closed loops
• No momentum transfer across nodes – higher pressure drop for cases with high velocity
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Process equipment in OLGA 6
• Controllers are signal network components – Coupled in the controller signal network
• Separator is a flow network component – Similar to multi-train separator in OLGA 5
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The OLGA 6 code is parallelized
• developed for multi core platforms, and may givesignificant performance boost when run on such systems
• Most benefit for –
large cases with few nodes, long pipelines and a relativesmall amount of process equipment
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What hardware is recommended to achievemaximum performance with OLGA ?
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Effect of several cores and CPU’s
Tested using 2 Quad core Intel CPUs with Hyperthreading(2 threads per core)
Speedup is case dependent
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1 2 3 4 4+4 2*(4+4)
N o r m a
l i z e
d w a
l l c
l o c
k t i m e
Cores+Hyperthreading
Oil field Gas-condensate
Running 2 CPUs onsame machine
Running 2 threads oneach core(Hyperthreading)
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What CPU to buy?
• Speedup is dependent on e.g. – Size of problem – Dominating flow regime – Modules used
• True multicores give good speedup• Good effect of Hyperthreading (Intel)• Effect of multi-CPU for larger problems• AMD and Intel Quad core give good speedup• Expects good performance on new 6 and 8 cores CPUs
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Is OLGA compatible with Windows 7 ?
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Windows 7 compatibility•
Yes, with some known exceptions
• OLGA is not supported on – PCs with Windows 7 + integrated Intel graphic card and
integrated Intel driver
• Following issues happen more often on Windows 7 – ‘Copy as picture’ of the network view to clipboard fails – Input report does not include image of the network view
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Can OLGA simulate Water Hammer effects?
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Water Hammer simulations in OLGA
• Hammer effects occur in liquid systems with fast transients – Injection systems
• Maximum hammer pressure :
P = Pressure (Pa)c = Wave propagation velocity (speed of sound) (m/s)v = Fluid flowing velocity (m/s)ρ = Density (kg/m 3)
• Maximum hammer pressure achieved if valve closure time is
shorter than system response time:
L = pipeline length
l l vc P max
c
Lt
r
2
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Water Hammer simulations in OLGA
• Fluid packingcontributes topressure increase
• Small spatialdiscretizationgives betterresolution ofpressure wave
4 km long pipeline with flowing water
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Water Hammer simulations in OLGA
• Elastic walls
• more correctvolume change &speed of sound
4 km long pipeline with flowing water
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Why does not always the 2 nd order numericalscheme give more accurate results?
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2nd Order Scheme for Mass Equations
• It should be used for cases with holdup or concentrationgradients e.g.
– Start-up – Rate change –
Slugging – Injection of inhibitors
• 2nd order scheme is not recommended for simulations whereinstabilities are observed
•
enhances the numerical oscillations
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Why is AXIALHEAT not included in OLGA 6?
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AXIALHEAT• Not implemented in OLGA 6 yet because
– Model in OLGA 5 is sensitive to pipeline geometry – Should only be used for vertical risers – No field data is available
• May be included in later versions depending on feedbackfrom users
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be dynamic