Retention system for bottom hole assembly and whipstock

A retention system for a bottom hole assembly and a whipstock comprising:

• a retractable bolt at least partially disposed in the bottom hole assembly;
• a retraction actuator capable of selectably opposing a retraction force on the retractable bolt;
• and
• meshing features on the bottom hole assembly and the whipstock, wherein the meshing features slideably mesh and slideably release without rotation between the bottom hole assembly and the whipstock.

A method of milling a wall in a wellbore comprising:

• coupling a whipstock to a bottom hole assembly with a retention system, the retention system comprising:
• a retractable bolt biased to retract into the bottom hole assembly;
• and
• a retraction actuator configured to resist the bias of the retractable bolt;
• after the whipstock and the bottom hole assembly have been disposed in the wellbore, activating the retraction actuator so that a retraction of the retractable bolt ensues;
• and
• milling the wall in the wellbore using the bottom hole assembly.

A method of milling a casing comprising:

• coupling a whipstock to a bottom hole assembly, the bottom hole assembly having a retractable bolt, the coupling comprising:
• engaging recesses of a mill face of the bottom hole assembly with protrusions of the whipstock;
• applying a retraction force to the retractable bolt;
• and
• using a retraction actuator to selectively oppose the retraction force on the retractable bolt;
• and
• activating the retraction of the retractable bolt after the whipstock and the bottom hole assembly have been disposed in a wellbore, wherein the retractable bolt moves without destruction during the retraction.