US Patent 7478687 Coiled tubing conveyed milling

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 supports a mud motor to drive the mill. Return fluid is separated from the cuttings and returned to the surface.