Apparatus for removing a section of casing or lining from a well-bore, and methods

Apparatus and method for removing a section of casing or lining from a wellbore. A tubular mandrel has a sliding assembly mounted thereon with grippers coupled to the assembly so that the grippers can be moved between an engaged configuration were they grip the inner wall of the casing section and a disengaged position were they are held away from the inner wall. A switcher is mounted on the mandrel which operates on entering the casing section to lock the grippers in the disengaged position so that cutting of the casing may be done. On pulling the switcher from the casing section, the grippers are automatically engaged and grip the upper end of casing section so that it can be removed. Additional locking arrangements are described which, by rotation, maintain the grippers in the disengaged position regardless of the location of the switcher.