Milling in casing that is over 4½ inches is done with coiled tubing that is anchored against torque reaction. An improved debris catcher is part of the bottom hole assembly to capture cuttings from the milling. A thruster can be used to maintain weight on the mill during the milling. The coiled tubing...http://www.google.com/patents/US7478687?utm_source=gb-gplus-sharePatent US7478687 - Coiled tubing conveyed milling
