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Wet Gas Pipeline And Oversized Pipeline-Liquid Hold Up

liquid hold ups

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#1 ziba

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Posted 16 October 2014 - 03:29 PM

Dear colleagues

 

Hi:

 

 we have a client who wants to re use a 36 " and 42" trunk produced wet gas pipeline with 16" laterals connected to trunk in new application.

 

They insist to use the built pipeline which is  oversized already.

 

The pipeline gathering system was designed to operate in Gas lift mode, now we are doing a ESP pump conversion , so there is not much  gas  at all.

 

As design is changed , gas velocity is very small ( 2m/s)liquid hold up may cause problems, slug and freezing happens, however the electrical heat trace need to be in service all the time.

my question:

 

When we have ESP pumps, how does it affect the produced gas pressure, how they manage the gas pressure when it is in ESP mode.

I need some information from people who did the same improvements.

 

Do you have any article about Gas lift conversion to ESP? WHAT ABOUT PIPELINE VACUUM GENERATION DUE TO CONDENSATION OF GAS, PIPELINE ON LOW POINTS MAY ACT LIKE A VESSEL HOLDING LIQUIDS.

 

we only require 16" trunk pipeline, line is 12 kilometers with up to 50 meters elevation increase, So I am very concerned about liquid formations and the only tool we have is hysys which is not enough at all.

 

How can I convince client to build a proper gathering pipeline, imagine that they do not want to spend money at all.

 

My boss also doe not let me do heat transfer analysis on pipeline, 50% of gas is water vapor at 160 C and 650 kPag.

 

plus :  gas is sour and I am worried about corrosion, for god sake what should I do with this type of clients? thanks all


Edited by ziba, 16 October 2014 - 04:12 PM.


#2 fallah

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Posted 17 October 2014 - 12:31 AM

Dear Ziba,

 

 

Appears the matter is about the "Artificial Lift Methods"...

 

A sketch of the system can assist to submit a better response.

 

Hope the links included in the attached file helps you out...

Attached Files


Edited by fallah, 17 October 2014 - 01:38 AM.


#3 ziba

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Posted 17 October 2014 - 11:41 AM

Hi Mr Fallah:

 

Thanks for information about ESP pumps, but my problem is not the pump and the new technology, the problem is that produced gas pipeline of 12 kilometers is over sized, we do not need a 36" trunk line for new application now.

 

When pipeline is oversized and we deal with wet gas, liquid hold up will be the major problem especially when system is running after shut down.

 

my client want to use a 36" pipeline for a wet sour gas with about 15 times less volume and I do not know how to convince them.

 

Alberta cold winters causes produced gas condensation and if the condensate removal system is not in service(i mean broken steam traps which is normal)they can not gather condensate, your help regarding this matter will be appreciated.

 

I also  always use OLGAS method to analyze pipelines with incline and elevation differences, my supervisor uses Beggs and Brill method which is very weak in hold up calculation and the worst part is that he does not consider heat transfer,  in real life heat transfers, we can not ignore it and we can not ignore condensation 

 

the problem is when the gas velocity is lower(because of oversized line and less mass flow rate), hold up will be much worse.

 

thanks


Edited by ziba, 17 October 2014 - 11:45 AM.


#4 fallah

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Posted 17 October 2014 - 01:42 PM

Dear Ziba,

 

As you know in wet gas systems liquid hold-up is a function of the gas velocity and angle of inclination; then below 2 m/sec gas velocity if there would be a few degrees inclination, the liquid hold up will increase significantly...

 

As per the info you provided, and as you mentioned forming much worse liquid hold up is inevitable...

 

Is there a slug catcher at the pipeline end or pigging facility to remove the slugs frequently out of the pipeline? or methanol injection to prevent hydrate formation? If so, it might client is relied on such facilities to decide using existing oversized pipeline...


Edited by fallah, 17 October 2014 - 02:45 PM.





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