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How To Choose Separator Type, 2-Phase Or 3-Phase Separator In Oil Sepa

2-phase 3-phase separator oil separation

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#1 Wondor

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Posted 14 September 2015 - 08:10 PM

I'm studying offshore production process, such as FPSO, fixed platform.

 

As i know of, oil separation process is consist of 3 stages of separators

And usually 3-phase separator is used at the first stage so that they can separate bulk water at the early stage.

But some project uses 2-phase separator at the first stage which means they don't separate water at the first stage. 

 

What is the design crieteria? or decision procedure to choose 3-phase or 2-phase?

Is anyone who can explain me how to choose separator type, 2-phase or 3-phase separator at each stage in oil separation proess?

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Edited by Wondor, 14 September 2015 - 08:29 PM.


#2 PingPong

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Posted 15 September 2015 - 10:29 AM

I have no experience with designing this kind of systems. The water from the HP separator however will contain a lot of dissolved gas, so I expect that, if separated from the oil, that water would need to be flashed (degassed) in a separate vessel. By using a 2-phase HP separator the water simply flashes to the MP separator together with the oil.

 

Economics also plays a role in design decisions. As does preference, experience, .......



#3 demank

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Posted 28 September 2015 - 02:54 AM

It is also depend on how much oil flow (BOPD) together with water flow (BWPD).

If large amounts of water are expected, it may more economical to install 3 phase separator instead of 2 phase separator.

 

Another consideration is flowing pressure temperature of the wells. Where all wells are expected to have similar FTPs at all times, it may be advantegous to remove the free water early with installing 3 phase separator.



#4 Firoz Raja

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Posted 08 October 2015 - 08:43 PM

Dear Wondor,

A 3-phase separator is usually required when the hydrocarbon and aqueous phase needs to be separated for the downstream processing. For example, a 3-phase separator is required when it is necessary to separate oil & water for downstream processing of oil and/or custody transfer. For FPSO/platforms, it may so happen that the separated oil from the wellhead fluids needs to be primarily treated and then sent for further processing. In such an application there is a custody transfer and hence it's required to have near pure hydrocarbon liquid transfer. Likewise the case for water - water would be separated and treated to be used for variety of purposes like re-injection in well or general purpose washing, etc.

 

There would be an application where it is not mandatory to separate hydrocarbon liquid and water but just to knock off the liquid from the vapors. For example, a suction to the booster and/or gas lift compression application. For such a scenario, a 2-phase separator would suffice.

 

Hope this helps.

 

Cheers,

Firoz 



#5 shan

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Posted 09 October 2015 - 06:17 AM

It is OK HP Separator is a 2 phase separator to save money by reducing dimension and weight for offshore oil/gas production facilities.  However, MP Separator and LP Separator should be 3 phase separators to meet crude BS&W.



#6 Wondor

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Posted 26 November 2015 - 02:02 AM

Another consideration is flowing pressure temperature of the wells. Where all wells are expected to have similar FTPs at all times, it may be advantegous to remove the free water early with installing 3 phase separator.

 

Do you mean;

 

If well FTP is changed, then the separation performance of 3-Phase separator would be worsen because HP Separator weir height is fixed at the begining?






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