Abstract: An apparatus and method are disclosed for the removal and replacement of the used drill bit after each perforation through casing, cement, and into rock while using a flexible drive shaft. This apparatus involves both a bayonet-style "quick connector" between the flexible shaft and the drill bit and a cartridge that holds the drill bits while they await their turn to be used. The apparatus also has a means for indexing the cartridge so that the flexible shaft can have access to each of the drill bits in the cartridge. The method disclosed involves the process of connecting the flexible shaft to the drill bit at the start of the perforating process, the disconnecting of the used bit at the end of the perforation, and the indexing of the cartridge so that the next drill bit is in line with the flexible shaft for the next perforation.

Abstract: An apparatus and method are disclosed for applying thrust (weight on bit) to a drill bit when drilling with a flexible drilling shaft while creating perforations in a cased well. The thrust is applied directly to the drill bit instead of applying it to the drill bit through the flexible drilling shaft. A support bracket is also in contact with a piston and is in slidable contact with the tool housing. A portion of the piston is positioned inside a chamber in the housing and is slidably attached to the chamber walls. As hydraulic fluid flows into the chamber opposite the piston, the piston is forced toward the drill bit. As the piston moves toward the drill bit, force is exerted on the support bracket which causes the bracket to move toward the drill bit. This force is transferred to the drill bit during the drilling process, thereby supplying the force (weight on bit) needed by the drill bit to effectively drill through a desired material.