| 摘要 |
A subsurface safety valve comprises a tubular body adapted for placement within a wellbore and defining a fluid passageway. A valve closure member, such as a flapper valve, is carried by the tubular body and movable through a closure path between positions opening and closing the fluid passageway. An actuator, such as a biasing spring, urges the valve closure member to its closing position. A flow tube is axially-movable within the tubular body between a first position preventing the actuator from urging the valve closure member to its closing position and a second position permitting the actuator to urge the valve closure member to its closing position. A latch assembly is provided for preventing movement of the valve closure member from its opening position to its closing position until the flow tube has been urged clear of the closure path. Aspects of the safety valve are employed by a related method and system.
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