| 摘要 |
A shear valve (1) for use in a downhole tool between the annulus and tubing in a well comprises an outer housing (11) and an internal body (13) movable in a longitudinal direction within the housing when the valve is activated, and at least one obstruction device (16, 10) which can be arranged to obstruct the internal body from moving. The obstruction device is capable of being deactivated by pressure from the tubing side of the valve. |
