A method and apparatus for anchoring a tool within a cased borehole wherein at least one piston connected with respect to the tool includes an associated anchor shoe. The anchor shoe has a penetration means, such as a plurality of wheels having a sharp outer periphery, for engagement with the cased borehole....http://www.google.de/patents/US6119782?utm_source=gb-gplus-sharePatent US6119782 - Method and apparatus for anchoring a tool within a cased borehole
