Gas Lift Chart Behaviour

[sinakult]

Hello,

I have a chart from a gas lifted well. Checkout the behaviour and tell me what you think is causing it. I know its switching between valves but it only does this at low gas lift system pressure.

Thanks,

S.

[Eng.Koriesh]

i think at low gas what happens that a deeper valve is not completely open , probably causing the gas coming into annulus to be less than gas coming out of annulus , which cause pressure build up in the annulus , to extent that open a shallower valve that time more gas come into tubing causing flow of higher rate and increase in well head pressure . the opening force in the shallower valve comes from the tubing pressure and annulus pressure , the low flow rate and low injection rate of gas caused a high tubing pressure in front of valve orifice so the valve opens in the low rate , in the high injection rate surging is less because deeper valve is completely open and handles the designed injection rate and hence cause tubing pressure to be low in front of the shallower valve and hence the valve is kept in close position .. then the rate of injection gas coming into annulus is equal to that leaving annulus through orifice . hence no surging is seen .