Water Injection Well Choke Performance (Cv)

[askinner87]

Evening Folks,

I have been tasked with evaluating choke performance on several water injection wells. I have 9 wells, all with the exact same choke, all injecting water. The first thing I did was calculate the Cv of each well at a given point in time. I then plotted it against the Performance Curve for the choke. 6 of the 9 the wells fell on the curve perfectly (yay!). But I had two wells fall above the curve and one well fall below the curve. I have two questions I am hoping the community can help me with

1)In simple terms what is being above or below the valve performance curve (Cv) telling me? is my choke eroded/plugged?

2)When completing an exercise like this, can I trust the upper & lower limits of the Cv curve? two of my outliers are on wells that have the choke open 97%

I have attached a chart of my calculations for illustration purposes.

Thanks in advance.

 

[LittleInch]

Saw this earlier then forgot to reply.

In simple terms if the Cv is higher than expected then you will get more flow than you anticipate for that opening percent with the same pressure drop. Lower then less flow than expected.

Remember the definition of CV for liquids - gallons of water per minute of water at a pressure drop of one psi.

Yes the CV limit is applicable at the ends, so it look like W1 4 & 4 might be shot and more flow is getting through than you expect, but WI6 might be plugged or not open as much as you think.



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