|
| US4176264 | 17 avr. 1978 | 27 nov. 1979 | Electro-Mechanical Products | Linear programmer for an actuator |
| US4206810 | 20 juin 1978 | 10 juin 1980 | Halliburton Company | Method and apparatus for indicating the downhole arrival of a well tool |
| US5014781 | 19 juil. 1990 | 14 mai 1991 | | Tubing collar position sensing apparatus, and associated methods, for use with a snubbing unit |
| US6032734 | 19 nov. 1997 | 7 mars 2000 | Weatherford/Lamb, Inc. | Activating means for a down-hole tool |
| US7673683 | 18 janv. 2007 | 9 mars 2010 | Welldynamics, Inc. | Well tool having magnetically coupled position sensor |
| US7779912 | 27 févr. 2007 | 24 août 2010 | Welldynamics, Inc. | Well tool having magnetically coupled position sensor |
| US8196656 | 8 sept. 2008 | 12 juin 2012 | Welldynamics, Inc. | Position sensor for well tools |