Gas lift valve

Claim 2

A gas lift valve for use in a well bore, said valve comprising: a hollow valve body having an outlet passageway and having an inlet port of smaller cross-sectional area than said outlet passageway; an annular valve seat located in said body between said inlet port and outlet passageway, said valve seat having a flow larger area larger than the cross-sectional area of said inlet port; a valve member in said body movable between a closed position, wherein said member engages said seat, and an open position, wherein said member is out of engagement with said seat; and pressure responsive means in said body connected with said valve member biasing said valve member toward said seat, said pressure responsive means being exposed to fluid pressure through said inlet port when said valve member is in the closed position and exposed to the fluid pressure in said outlet passageway when said valve member is in the open position, and said pressure responsive means having a cross-sectional area exposed to fluid pressure substantially equal to the crosssectional area of said valve seat, whereby the pressure acting through said inlet port has no substantial effect on said valve member or pressure responsive means.

Claim 3

A gas lift valve for use in a cased well bore having tubing disposed therein, said vale comprising: a hollow valve body adapted for connection with the tubing, said body having an outlet passageway arranged to communicate with the tubing and having an inlet port of smaller cross-sectional area than said outlet passageway providing communication with the casing; an annular valve seat located in said body between said inlet port and outlet passageway said seat having a flow area larger than the cross-sectional area of said inlet port; a valve member in said body move movable between a closed position, wherein said member engages said seat, and an open position, wherein said member is out of engagement with said seat; and pressure responsive means in said body connected with said valve member biasing said valve member toward said seat, said pressure responsive means being exposed to pressure in the casing through said inlet port when said valve member is in the closed position and exposed to pressure in the tubing when said valve member is in the open position, whereby the movement of said valve member between said positions is controlled by the pressure in tHe tuning tubing acting through said outlet passageway; and said pressure responsive means having a cross-sectional area exposed to fluid pressure substantially equal to the cross-sectional area of said valve seat, whereby the pressure acting through said inlet port has no substantial effect on said valve member or pressure responsive means. 3 The gas lift valve of claims 1 and 2 wherein said pressure responsive means extends across said hollow valve body forming a chamber therein and wherein said valve also includes a compressible gas in said chamber for biasing said pressure responsive means and connected valve member toward said valve seat.

Claim 4

A gas lift valve for use in a cased well bore having tubing disposed therein, said valve comprising: an elongated tubular body adapted for connection with the tubing, said body having a closed upper end, a lower end including an outlet passageway proving providing communication with the tubing passageway, and an inlet port intermediate said ends providing communication with the casing; an annular valve seat encircling said outlet passageway and having a cross-sectional flow area larger than the cross-sectional area of said inlet port; A valve member movable between a closed position, wherein said valve member is in engagement with said seat, and an open position, wherein said valve member is not in engagement with said seat; an expansible and contractible bellows in said body connected with said valve member and forming a chamber with said upper end; A compressible gas in said chamber biasing said valve member relatively toward said valve seat; and toward said valve seat; and said bellows being located between said closed end and side inlet port and exposed to fluid pressure from the casing through said inlet port when said valve member is in the closed position and exposed to fluid pressure from the tubing through said outlet passageway when said valve member is in the open position, and said bellows having a cross-sectional area exposed to fluid pressure substantially equal to the cross-sectional area of said valve seat, whereby the casing pressure acting through said inlet port has no substantial effect on said valve member or bellows.

Claim 5

A gas lift valve for use in a cased well bore having tubing disposed therein, said valve comprising: an elongated tubular body adapted for connection with the tubing, said body having a closed upper end, a lower end including an outlet passageway proving providing communication with the tubing passageway, and an inlet port intermediate said ends providing communication with the casing; an annular valve seat encircling said outlet passageway and having a cross-sectional flow area larger than the cross-sectional area of said inlet port; A valve member movable between a closed position, wherein said valve member is in engagement with said seat, and an open position, wherein said valve member is not in engagement with said seat; an expansible and contractible bellows in said body connected with said valve member and forming a chamber with said upper end; A compressible gas in said chamber biasing said valve member relatively toward said valve seat; and toward said valve seat; and said bellows being located between said closed end and side inlet port and exposed to fluid pressure from the casing through said inlet port when said valve member is in the closed position and exposed to fluid pressure from the tubing through said outlet passageway when said valve member is in the open position, and said bellows having a cross-sectional area exposed to fluid pressure substantially equal to the cross-sectional area of said valve seat, whereby the casing pressure acting through said inlet port has no substantial effect on said valve member or bellows.

Claim 6

The gas lift valve of claims 1, 2, or 4 wherein the cross-sectional area of said inlet port is at least 25 percent smaller than the cross-sectional area of said valve seat. 6 The gas lift valve of claims 1, 2, or 4 and also including surge valve means located in said outlet passageway said surge valve means including: a surge valve encircling said outlet passageway between said valve seat and surge valve member; a surge valve member in said outlet passageway; resilient means biasing said surge valve member toward, but not into engagement with said surge valve seat, whereby fluid pressure in said outlet is exerted through said outlet passageway and fluid flow thereby toward said valve member is substantially prohibited.