Questions regarding pipeline pressure drop simulations
Questions regarding pipeline pressure drop simulations
(OP)
Recently I did some pipeline pressure drop simulations however the result sounds not positive. When I use the defaut value of the pipe internal roughtness which is 1e-5m, the result cannot match the field data. Can somebody help me out this issue? I can change the roughtness, but it shows 0.008 m which to me not reasonable.
Thanks.
Thanks.





RE: Questions regarding pipeline pressure drop simulations
Or it could be that you missed some major "Minor" losses in your model. Any baffles, reducers, manifolds, etc?
Signature under construction, sorry about the mess - Steve
RE: Questions regarding pipeline pressure drop simulations
I agree with LHA - I am also thinking there may be some losses missing from the model?
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
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RE: Questions regarding pipeline pressure drop simulations
I've found that simulation programs, at least those on the major engineering and oil and gas companies approved lists, give results as good as the input data will let them.
OK, back to the flow. Gas or liquid? Or both?
Perhaps you have fouling, perhaps you have liquid accumulated in low points, maybe a valve is mostly closed, has a joint collapsed under a road crossing?, perhaps unaccounted "minor losses", but that would have to be a lot of them to add up to an average roughness of 0.008m, so that's probably not it. Good luck finding it! Start at the point where the head or ressure drop/meter length gets exceptionally large. Should be easy to see.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Questions regarding pipeline pressure drop simulations
4" line pipe, 2" insulation, underground, no reducer, 4.8mm wall thickness, 12650 m length
the fluid is gas+oil, gas flow rate is 96000 STD m3/day, oil flow rate is 388 STD m3/day, for gas, 30% H2S, oil specific gravity can be assumed 0.87, pressure at both end 4400 kPa and 2100 kPa respectively. temp. 38 degree C
I use this data and got the 0.008 m roughness.
RE: Questions regarding pipeline pressure drop simulations
The analysis is just not up to the task, and it may not be in our lifetime.
David
RE: Questions regarding pipeline pressure drop simulations
RE: Questions regarding pipeline pressure drop simulations
The ability for most models to calibrate on a fairly simple system is pretty good and the numbers kind of mean something. On a highly looped system with multiple off-system deliveries most fail miserably. I run what is probably the last functioning copy of MNET in the world because it can be calibrated to any system I've ever thrown at it. The company went out of business with a beta version of Window 3.1 compliant code on the streets. I've made the software security "dongle" do the last few system upgrades, but I don't think it will go from XP to Vista and I'm frantic to find a viable replacement. I've run 5 of the top name programs and all are "pretty", but none of them can meet my calibration criteria on my test case. I've got a salesman for one of them trying to match my field data and about a week ago he stopped calling with questions so I'm thinking that another program bit the dust.
You have to remember that a model is not reality. It is just a bunch of arithmetic trying to provide insight into how a piping system functions. If you can get a model calibrated, then for a brief period it can tell you very interesting things. BUT if your model disagrees with high-quality field data then the model is wrong. Simple as that.
David
RE: Questions regarding pipeline pressure drop simulations
In that case don't be too concerned about using any roughness that matches your pipeline flow & pressures under operational conditions. If it does that, its a good match.
It sounds like a simple Lockart-Martenelli model could do the job with parameter values that you might think are more reasonable. Let me know if you want to try my spreadsheet.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Questions regarding pipeline pressure drop simulations
You can set WinXP to run programs in a Win 95, 98/ME, 2000, or NT environment. Right-click on the execute and set the "compatibility" parameters.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Questions regarding pipeline pressure drop simulations
David
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
RE: Questions regarding pipeline pressure drop simulations
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Questions regarding pipeline pressure drop simulations
I also have problems to get the quality data. The software I use also offer the bulk properties (single phase model) option, I may try that one.
RE: Questions regarding pipeline pressure drop simulations
David
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
The harder I work, the luckier I seem
RE: Questions regarding pipeline pressure drop simulations
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Questions regarding pipeline pressure drop simulations
David
RE: Questions regarding pipeline pressure drop simulations
In looking at a replacement for MNET, please feel free to look at Korf Hydraulics (www.korf.co.uk). For info - I am involved with its development.