Patent ID: 7124827

Claim:
A whipstock assembly for use downhole in a wellbore to mill a hole or to divert a tool into the hole in a side of a casing string, the whipstock assembly comprising: a tubular anchor removably supportable on a running tool for positioning the tubular anchor downhole, the tubular anchor having an initial anchor inner diameter, and having an initial anchor outer diameter less than an inner diameter of the casing string, the tubular anchor being expandable by the running tool to seal with the casing string; a tubular expander removably supportable on the running tool, the tubular expander having an expander outermost diameter greater than the initial anchor inner diameter; the running tool including an actuator for forcibly moving the tubular expander axially from a position substantially axially spaced from the tubular anchor to a position substantially within the tubular anchor, thereby radially expanding the tubular anchor against the casing string to secure the tubular expander and the tubular anchor downhole; and a whipstock engageable with the tubular expander for orienting a whipstock face for milling the hole or diverting the tool into the hole in the side of the casing string.