| 摘要 |
Apparatus and methods are provided for actuation of downhole tools. In one example, a deep set safety valve 12 uses a magnetic coupling 52 which permits a portion of the safety valve 12 at control line 18 pressure to be isolated from tubing string 14 internal pressure, without requiring the use of a dynamic seal therebetween. A piston 32 of the safety valve 12 may be displaced in response to a differential between control line pressure and pressure in an annulus 38 surrounding the tubing string 14, pressure in another control line, or pressure in the tubing string 14. The magnetic coupling is between an actuator member and a magnetic field generating means connected to an operating member. |
