DIFFERENTIAL PRESSURE GAS LIFT VALVE

1,244,063. Raising liquids by aerating an ascending column. BAKER OIL TOOLS Inc. Aug.8, 1969 [Oct.3, 1968], No.39780/69. Heading F1R, In a gas lift valve 100 used to inject highpressure gas for raising liquids in a tubular string of a well bore a valve member 29 shifts in a housing 24 between a closed position engaging a valve seat 27 to prevent high-pressure gas which enters through the side chokes 30 to flow via the seat into the tubular string and an open position to permit such flow. The valve member 29 has a first surface Ap subject to gas pressure provided from a tubing annulus K and a second surface Av subject to liquid pressure in the tubular string when the valve is engaged with the seat 27 and a spring 38 urging the valve member 29 toward open position, the area of the first surface Ap being greater than the area of the second Av. A valve seat 25 is adapted to be engaged by a ball check valve element 26 to prevent reverse flow of liquid from the tubing string. In the open position the flow of gas through the throttles 30 accelerates and gas pressure acting downwards on the valve 29 is exceeded by the greater pressure acting upwardly over the area Ap which shifts it to the closed position. In another embodiment, Figs.4a, 4b the gas lift valve is located within the tubing string T and comprises a section 50 threadedly secured to the tubing string and containing an outer housing structure 55 and an inner housing 70 which is threadedly attached to anupper cage 73 to which the housing 75 of the gas lift valve 101a is secured. This valve is the same as the one 100 in, Fig.2. Gas under pressure from the tubing-casing annulus K enters the inner housing 70 via ports 69, 79 and ball check valve 81 flowing through the chokes 30 and valve seat 27 to the tubing string T thereabove. At the same time liquid flows via passages 84 and annulus 85 into the tubing string T. A suitable retrieving tool can be run in on a wire line through the tubing string T to engage and retract latches 64 and also become coupled to a mandrel 62 to retrieve the valve assembly. In the embodiment of Fig.8 (not shown) the lift valve has a central orifice 95 through which gas can flow continuously when the valve is closed. The valve may be used with a diffferential pressure liquid control valve (N) Fig.1 (not shown) installed in tubing string T along which a series of spaced preset gas lift valve (101 may also be installed.