| 摘要 |
A subsurface safety valve for controlling a fluid flow through a well conduit includes a housing having a bore and disposed within an annulus defined by the space between the well conduit and the housing, a valve closure member movable between an open position and a closed position, and adapted to restrict the fluid flow through the bore when in the closed position, a flow tube moveably disposed within the housing and adapted to shift the valve closure member between its open and closed positions, a primary piston member in operative communication with the flow tube and a secondary piston member in operative communication with the flow tube. |
