GAS LIFT VALVE UNIT Russian patent published in 2011 - IPC E21B34/06 

FIELD: oil and gas production.

SUBSTANCE: device consists of gas lift valve with shut-off valve element positioned between circular space and channel of lifting pipe. The element selectively transmits a flow of fluid medium from an inlet side to an outlet side of the shut-off valve element. Also, the element shifts to prevent leakage of fluid medium from the outlet side to the inlet side. There is an isolating element on the inlet side of the shut-off valve element. The isolating element is lowered into a well in the first position when it isolates outlet of the shut-off valve element under pressure of fluid medium in circular space or channel of the lifting pipe for prevention of leakage of fluid medium. When a level of fluid medium pressure exceeds the threshold level, the isolating element passes into the second position. In the latter position the isolating element transmits fluid medium through it regardless of fluid medium pressure.

EFFECT: increased reliability of device operation.

19 cl, 12 dwg