Patent ID: 8393402
Filing Date: 2013-03-12
Classification: E21B

Abstract:
1. A redundant position reference system for multilateral exit construction in a wellbore, the system comprising: a casing string positioned in the wellbore; a window joint interconnected in the casing string; a first latch coupling interconnected in the casing string downhole of the window joint, the first latch coupling having a first inner profile; a first whipstock assembly operable to be run in the casing string, the first whipstock assembly including a first latch assembly having a first mating profile operably engagable with the first inner profile to anchor and orient the first latch assembly within the first latch coupling and to axially locate and circumferentially orient a first deflector surface of the first whipstock assembly within the window joint; a second latch coupling interconnected in the casing string downhole of the first latch coupling, the second latch coupling having a second inner profile that is different from the first inner profile; and a second whipstock assembly operable to be run in the casing string, the second whipstock assembly including a second latch assembly having a second mating profile operable to pass through the first inner profile and operably engagable with the second inner profile to anchor and orient the second latch assembly within the second latch coupling and to axially locate and circumferentially orient a second deflector surface of the second whipstock assembly within the window joint, thereby providing redundant access to the window joint.