installing check valve on wellhead manifold

[hakeem64]

Hi
I am working in oil production company , which have some wells ESP pumps with no check valve(removed) at the discharge line .
This happen because of ease of work over operations ,and difficulty of emptying the tubing line for some scale problems. ESP backspin is taking place at shutdown with restart alarm signal to protect the pump .
Therefore ,We planing of install check valve at well head flow line(4KM long ) to minimize flow line fluid from backflow to the well bore at any ESP shutdown event .

Please advise if this can be done.

Thanks

 

[LittleInch]

hakeen64,

In a word probably not. It depends what your top hole pressure is once you stop the ESP and close the wing valve. So long as this above a min of say 5 barg, then it could work, but if your fluid has a lot of gas, you will still get quite a lot of back flow as the gas evolves from the well fluid and allows the liquid to flow backwards. The issue is if the field bottom hole presusre is now so low that it cannot support the oil / water column in the well bore and if you stop the flow and isolate at the well head then the fluid will simply pull a near vacuum and allow the liquid to flow back into the reservoir. Then it doesn't matter what you do - you then need to fit check valves immeadiatly downstream of the ESP. Come to think of it are there non on the ESP itself??

Use of check valves should only ever be a back-up before use of a proper isolation valve. Are there no actuated valves on the wellhead that you could link into the motor control system to close when the pump stops??

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[hakeem64]

Thanks for the reply

For sure there is no check valve downstream of ESP and at the wellhead beside the choke valve.there is no actuated or non-actuated isolation valve except wing valves on wellhead tree.

 

[LittleInch]

Ok, Sounds a bit alrming to me to not have any actuated valves, but if that's what you've got then Ok. what are pressures you're delaing with such as flowing wellhead presusre, manifold pressure, SITHP after ESP suhtdown, GOR, water cut etc.

As I said you need to see whether instalation at the manifold will mactually work or not and without this info it is diffcult to judge.

The cost of pulling an ESP which is being dmaged by reverse flow must be much bigger than installing a wing valve actuator so you may need to consider this in terms of what you save. Check valves are only a short term / non reliable flow shut off device and should never be substituted for proper isolation valves.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way