HSP - ESP

[cesarcf1977]

Hi.

Anyone with some knowledge about HSP pumps can tell me why they are better than ESPs regarding gas handling capabilities? I mean, they are both centrifugal pumps, one uses electric power and the other uses power fluid so, what makes them different for gas handling purposes?

Thanks.

Regards.

 

[DrillerNic]

It's to do with the direction of flow through the impeller.

If the fluid goes through the impeller in the same direction as flow (i.e. like a propeller), it's called axial flow. If it goes through the impeller at right angles to the flow direction it's called radial flow, if it's somewhere between these two it's called mixed flow. ESP impellers are either radial or mixed flow.

Radial flow impellers are less good at dealing with gas in the fluid, as they tend to gas lock, but you get a high increase in pressure per impeller. Axial impellers are excellent at dealing with gas (think of aircraft propellers) but they have a very low delta P per stage.

To get the required pump pressure increase with axial flow impellers we can do two things: either use thousands of axial impellers running at typical ESP speeds, resulting in a axial flow ESP hundreds of feet long, (which I certainly wouldn't like to try running in hole!)

OR

A similar number of impellers to an normal ESP, but running at much higher speeds than a normal ESP. ESPs are usually limited to about 3600rpm as the electrical power supply is ususally 60Hz. So use a power fluid to spin a turbine at higher speeds and drive the pump with the turbine. (I guess you could try to get electrical power at a higher frequency than 60Hz, but that would be hard and expensive to do). i.e. the Wier HSPs running on Captain run at 5000-7500rpm and go up to 10,000rpm for gassy slugs.


Or, for gassy crudes, use downhole gas separators and normal ESPs, which is what Schlumberger or Centrilift will try to sell you.....

 

[zdas04]

Doesn't "HSP" stand for "Hydraulic Stroking Pump"? If so DrillerNic has only told half of the story (i.e., why ESP's have a problem with gassy liquids).

I'll delay further pontification until I hear for sure what an HSP is.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The Plural of "anecdote" is not "data"

 

[25362]

To cesarcf1977, please confirm or deny whether the meanings of your acronyms are:

Electrically-driven Submersible Pumps - ESP
Hydraulically-driven Submersible Pumps- HSP

Thanx.

 

[DrillerNic]

As he refers to both ESPs and HSPs being centrifugal pumps, one driven by electricity and one by a power fluid, I'm assuming that cesarcf1977 means Hydraulic Submersible Pump by HSP. The tone of his question would also suggest this- I doubt if anyone would compare an ESP with a traditional hydraulic pump (the HSP that Dave Simpson refered to, which I think is sort of a down hole driven beam pump- is that right Dave?)

 

[Alph]

An earlier thread

http://www.eng-tips.com/viewthread.cfm?qid=101531

Weir Pumps - HSP

http://www.weirclearliquid.com/clearliquid/home.nsf/luProducts/Weir_HSP?OpenDocument&view=cat

Article
SPE88837 – A case Study in the Design and Execution of Subsea Production Development Wells in the Captain Field. (June 2004 SPE Drilling & Completion)

 

[zdas04]

yeah, a hydraulic stroking pump is a rod-pump-like gadget that replaces the rods with an hydraulic stroking motor downhole.

I've seen a lot of people recently compare ESP to PCP to jet pumps to stroking pumps to beam units for gas well deliquification. Since all of these technologies were developed for oil wells (where the pumped liquid is the commercial product, not a waste product) a lot of people are really struggling with this topic and the options are pretty wide open.

Most companies I work with these days don't differentiate electric drive from hydraulic drive on surface-drive PCP's. I didn't realize that there was a downhole hydraulic drive head for for a submersible centrifigal pump. Learn something new every day here.

David

 

[d23]

I thought you could get an axial flow design with ESP’s.

http://www.oilfield.slb.com/content/services/artificial/submersible/poseidon.asp

DrillerNic,

Just so you know there is Francis flow impellers too. They perform better than mixed flow, but not as good as axial in both gas and solids applications.

D23

 

[DrillerNic]

d23- could you tell me more about these Francis flow impellers please?

Alos, thanks for the link to brother blue's latest offering for gassy ESPs. My friendly Centrilift representative claimed up to 60% gas fraction with special vanes in the radial impeller of their pumps....

I don't know how much run time data SLB or Centrilift have for their high GOR ESPs, but Wier have quite a lot of data for their HSPs. The Wier HSP is pretty big though (10" OD for 11-3/4" csg). Pays yer money, makes yer choice!

Dave- I've used jet pumps to unload an ERD oil well, which was pretty successful (personally I love jet pumps and I think it's criminal that they're not more popular)! Gas well unloading is also a pretty common topic at my company, togther with that other perennial question, black start gas lift.

 

[d23]

DrillerNic

There is a reason not to use any radial flow impeller in a gassy application. Radial flow impellers with “special vanes” cannot perform as well as Mixed, Francis or Axial impellers with free gas.

A Francis impeller is a design that falls in-between mixed flow and axial flow impeller.

All “ESP” companies have several “Rules of Thumb” about producing free gas that they tell their employees. The Centrilift statement of “up to 60 percent gas fraction” is a good example of that. The key words in that statement are “up to.” Anytime you have an application above 30% free gas you need to find someone that can explain why it will or will not work without a “rule of thumb” being involved.

I apologize, but this discussion could turn into a “proprietary information” discussion very fast, so I'll leave it at this.

D23