Method and apparatus for orienting a whipstock in an earth borehole

摘要

A reference sleeve is used to orient a whipstock assembly to direct a pipe string into a new borehole section. The whipstock assembly may be removed such that a pipe string may enter the original borehole through the relatively large inner diameter of the expanded reference sleeve. The reference sleeve provides a permanent reference without forming an obstruction in the wellbore. To go back into the new borehole section, the whipstock assembly will be oriented automatically within the reference sleeve such that a pipe string will be reliably directed into the new borehole section, even years later. The reference sleeve is preferably run into the hole in a running position that is radially compressed. After orientation, the reference sleeve is expanded to thereby engage the wellbore and be affixed in position. Orientation surfaces include sloping guide surfaces and a slot that mate to a key on the whipstock assembly. The reference sleeve may be used for any reference purpose in the wellbore, e.g., for providing a wireline logging depth reference.