Abstract: A combination metal milling and earth drilling tool, for use in performing a single trip kickoff from a casing in a well bore. The combination milling and drilling tool has a first, relatively more durable cutting structure, such as tungsten carbide, and a second, relatively harder cutting structure, such as polycrystalline diamond. The more durable first cutting structure is better suited for milling metal casing, while the harder second cutting structure is better suited for drilling through a subterranean formation, especially a rock formation. The first cutting structure is positioned outwardly relative to the second cutting structure, so that the first cutting structure will mill through the metal casing while shielding the second cutting structure from contact with the casing. The first cutting structure can wear away while milling through the casing and upon initial contact with the rock formation, thereby exposing the second cutting structure to contact with the rock formation.

Abstract: A retrieval tool for whipstocks is disclosed. A latch is retractable into the tool upon application of hydraulic pressure. A locking pin securely fastens the whipstock and retrieving tool together. The hydraulic pressure acts a cleaning force on the top of the whipstock and the retrieving slot to facilitate engagement. The offset stabilizer, when oriented opposite the lug on the retrieving tool, creates a force in the direction of the lug, whereby latching the retrieving tool will start. A joint of drillpipe or heavyweight drillpipe is run above the eccentric stabilizer. An offset stabilizer is provided to ensure proper initial orientation and avoid sticking the tool. The latch can firmly grip lugs within a slot in the whipstock. A overshot design is also disclosed using a similar hydraulically actuated latch assembly where the latch grabs the whipstock without having to use an opening therein, if for any reason the opening has been fouled with debris or damaged due to milling.