Gas lift valve having edge-welded bellows and captive sliding seal

摘要

A gas lift apparatus has a gas lift valve that disposes in a mandrel. A housing of the valve has a chamber, and a seat disposes between the inlet and outlet. A piston movably disposed in the housing has one end exposed to the chamber. A distal end can selectively seal with the seat to close the valve. A first edge-welded bellows disposed on the piston separates the inlet and chamber pressures and can fully compress to a stacked height when the distal end of the piston seals with the seat. A dynamic seal can be achieved at closing by using a captive sliding seal between the piston's distal end and the seat. A second edge-welded bellows can also be disposed on the piston, and the two bellows can operate in tandem. Oil filing the interiors and the passage can move from one bellows to the other to transfer the pressure differential between the inlet and the chamber pressures. The second bellows fully compresses to a stacked height and stops opening of the valve.

主权项

1. A gas lift apparatus, comprising:
a housing having a chamber, an inlet, and an outlet and having a first seat disposed between the inlet and the outlet; a piston movably disposed in the housing, the piston having a proximal end exposed to chamber pressure and having a distal end exposed to inlet pressure, the distal end sliding relative to the first seat and selectively sealing fluid communication through the first seat; first and second edge-welded bellows disposed on the piston and separating the inlet pressure from the chamber pressure, the first edge-welded bellows fully compressing to a first stacked height at a point when the distal end seals fluid communication through the first seat, the second edge-welded bellows fully compressing to a second stacked height when the distal end is distanced away from the first seat, wherein the piston comprises an internal passage communicating a first interior of the first edge-welded bellows with a second interior of the second edge-welded bellows.