Patent ID: 7000703

Claim:
A method of forming a wellbore junction in a subterranean well, the method comprising the steps of: drilling a first wellbore; installing a casing string in the first wellbore; drilling a second wellbore extending outwardly from the first wellbore; aligning a window formed through a sidewall of the casing string with the second wellbore; installing a liner string through the window and into the second wellbore, an end portion of the liner string extending inwardly through the window; and then radially outwardly deforming the liner string end portion to form a flange thereon, the flange preventing outward displacement of the liner string through the window, and wherein the deforming step further comprises conveying a deflection device and mandrel into the casing string, and displacing the mandrel relative to the deflection device, thereby laterally deflecting the mandrel to deform the liner string end portion.