Patent GB-1084907-A (GB)
Title: Double seated gas lift valve
IPC: E21B43/12
Filed: 1964-10-14
Abstract: 1, 084, 907. Raising liquids by aerating an ascending column. OTIS ENGINEERING CORPORATION. Oct. 14, 1964 [March 9, 1964], No.42001/64. Heading F1R. [Also in Division F2] A gas lift valve comprises an annular main closure member 48 engaging a seat 41 in the valve housing, and a secondary closure member 51 engaging a seat 52 in main closure member 48, secondary member 51 being operated by a liquid-filled bellows 64, the upper end of the bellows communicating with a liquid-filled chamber 70 having a gas or spring-loaded piston 72 of limited upward stroke to prevent pressure damage to the bellows. In operation, the liquid column in well tubing T acting on the underside of the secondary valve member via passage 26, and the lift gas pressure in casing C acting on the outside of bellows 64 via port 39, act to open the secondary valve to admit gas pressure to the underside of the valve members via passages 55 and 53, the gas pressure then contracting the bellows to open both valves. When the liquid column above the gas reaches the well surface, the gas pressure falls, and the gas or spring-loading on the bellows acts to close the valves. The valve may be mounted to control gas flow from the tubing to the casing, or may be mounted in an inverted position, in which case the main valve member may be made sufficiently massive to be moved from its seating by gravity. In another embodiment, the pin coupling 57 between the secondary and main valve members is replaced by a spring acting between shoulders on the valve members to bias the secondary valve member on to its seat. Alternatively a spring may act between the main valve seating and a flange on the main valve member, or the main valve member may be biased into engagement with the secondary valve by magnets secured to the valve members. In Fig. 12 (not shown), the valve members are coupled by collet fingers (190) on the secondary valve member, engageable with a flange (198) on the main valve member. In the embodiment of Fig. 13 (not shown), a pilot valve (249) is opened by the well liquid pressure in tubing T acting on the underside of valve (249) via port (208), piston passage (241) and passage (247), and the lift gas pressure acting on the outside of bellows (255) against gas pressure in chamber (262) acting on the bellows interior. Opening of valve (249) admits lift gas to the upper surface of piston (236) to open secondary valve member (221) against lift gas pressure acting via gas inlet port (223), pressure equalization across main valve (216) via clearance (222) then opening the main valve. When the lift gas pressure falls, bellows (255) closes pilot valve (249), pressure equalization then taking place across piston (236) via passage (241), and the pressure differential across valve members (216), (221) due to the gas flow then acts to close the valves. In another embodiment, the ports are arranged for control of gas flow from the tubing T into the casing C. In the embodiment of Fig. 16 (not shown), a check valve (327) is provided in the gas passage, and the seating surface of the secondary valve member is constituted by a ball (353). Upward movement of the valve assembly is limited by engagement of a flange (371) with a shoulder (373). Seals (312), (317) are provided on the valve housing for engaging the walls of a valve pocket in the well tubing or casing. The secondary valve member is connected to a rod (370) having a piston at its upper end subjected to spring or gas pressure, the bellows and a chamber between the bellows and the piston being filled with liquid.