| 摘要 |
Embodiments of the invention generally relate to a failsafe subsurface controlled safety valve. In one embodiment, a failsafe subsurface controlled safety valve assembly (40) includes: a tubular housing (41); a closure member (43) disposed in the tubular housing, wherein the closure member is movable between a closed position and an open position; an operating piston (45) operable to move the closure member between the closed position and the open position; and a trigger piston (46) operable to move the closure member from the open position to the closed position. |
