| 摘要 |
A mudsaver valve is described that has a bi-directional snap action in opening and closing the valve. The mudsaver valve is adjustable for different mud weights and includes a preassembled valve cartridge for ease of assembly. Furthermore, elevated pressure from below is readily transmitted past the valve seat, so that the standpipe pressure of the well can be determined through the valve when the pumps are stopped and mudsaver is still connected to the drillstring. One embodiment of the mudsaver valve also contains a mechanism whereby the valve may be locked open by an accessory tube whenever a pipe gets stuck and becomes inaccessible, thereby permitting wireline operations through the valve so that the pipe may be freed.
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