high water cut in crude oil transfer pump

[Meshry]

What is the impact of increased water cut in crude oil on the transfer pump i.e. centrifugal multistage?

 

[LittleInch]

Increase in pressure

Increase in power consumed

Both due to increase in fluid density.

Look at pump data sheet compared to actual.

could add 25% to both (SG 0.8 to 1.0)

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Meshry]

LittleInch,
Thanks for your reply. still I have some doubt.
Yes, increasing the density will increase the pressure and power.
what about the effect on the pump internal parts i.e. is there any possibility for pitting due to cavitation?
what about rotor stability with two phase fluid?? i am more worry about pump healthiness than the more power consumption.
for pump data sheet there are two values for the water cut:
2% aearated water and 1% for entrained water. this is not clear for me!!!

 

[LittleInch]

There shouldn't be any impact, but maybe the water cut has affected the system on the inlet side.

Unless the water is coming through as slugs of water followed by oil the rotor should be ok.

I think aerated water means free water and entrained means in solution or emulsion. Either way it's a very small amount.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

Also check with a pump engineer what effect this may have if discharge pressure varies frequently due to water cut fluctuations and what this may do to the plan 53B seals on the pumps further downstream.
Same concern if there is significant amount of gas carryunder from the source separator into the first stage pump suction.

 

[Alexander R.]

Meshry,
2% water content is not high water cut. For transfer of crude oil to processing facilities, it is usulal to specifiy max 0.5% of basic sediments and water (BS&W). In case of higher water content centrifugal pumps tends to emulsifiy the fluids, which would affect downstream separation facilities. But generally it has no negative effect on the pump itself.

 

[Meshry]

Gents,
Thanks a lot for your great replies.

Alexander,
Do you mean 5% or 0.5%, can you explain more?

 

[LittleInch]

I'd go with zero point 5 percent as a pretty standard export Crude specification for BS & W.

Upstream of course you can get >95% water cut in some places....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Meshry]

Ok.
Today report showed 5% water cut. Because it is the winter time so separation process is not efficient.
Can we continue running the transfer pump in this condition?
As per Alexander's reply. It is max 0.5%

 

[LittleInch]

Pump should be no problem at 5%

Export spec is up to you

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Alexander R.]

As LittleInch says its no problem for pump at all, 0.5% or 5%, or whatever WC you have. My point was to mention that in presence of both oil and water, centrifugal pumps in general tend to emulsify the flow. Emulsions would have slight increase in viscosity, which would increase the pressure drop in the pipeline slightly. But it has no impact on the pump performance itself.

 

[Meshry]

Thanks to all for your replies