| 摘要 |
A technique to allow a control chamber of a tool to be designed to operate safely at a much lower pressure than the well fluid pressure, thus allowing the diameter of the internal well fluid passageway in the string to be maximized. A chamber 170 is provided in a well tool 150 to receive pressure to control an operation of the tool and a seal 169 is provided to isolate the chamber 170 from the well fluid. A pressure relief mechanism (fig.4. 190,) such as a rupture disc or relief valve, is used to relieve pressure from the chamber 170 if the seal 169 fails and the chamber pressure exceeds a set threshold. |
