Method and apparatus for retrieving a whipstock

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. Generally, release from the whipstock cannot occur unless hydraulic pressure is reapplied to release the latch and locking pin, thus allowing them to retract toward the body of the retrieval tool.