| 摘要 |
A wellbore valve assembly (12) including a valve member (20) which is moveable relative to the valve seat (14), the valve assembly (12) being receivable in a wellbore tubing (10) having a first end (10a) and a second end (10b), the valve member (20) being moveable between an open position relative to the valve seat (14), and a position in which the valve member (20) is seated against the valve seat (14), the valve assembly (12) including a valve member biasing device (22) for biasing the valve member (20) towards the open position, the valve member (20) being operable to close in the event of a force which exceeds a predetermined value being applied in either direction relative to the direction in which the valve member biasing device (22) acts. |
