Patent ID: 8833439
Filing Date: 2014-09-16
Classification: E21B

Abstract:
1. A casing string having an axial direction, the casing string positionable in a wellbore, the casing string comprising: first and second steel casing joints threadably interconnectable within the casing string each having a radially reduced section; an aluminum exit joint positioned between the first and second steel casing joints, the aluminum exit joint having a first threaded interconnection with the first steel casing joint and a second threaded interconnection with the second steel casing joint, the aluminum exit joint operable to have a window formed therethrough; a first sleeve positioned interiorly within the first threaded interconnection and extending in the axial direction from within the aluminum exit joint into the radially reduced section of the first steel casing joint such that an outer surface of the first sleeve contacts the aluminum exit joint, the first threaded interconnection and the radially reduced section of the first casing joint, thereby providing galvanic isolation between the aluminum exit joint and the first steel casing joint; and a second sleeve positioned interiorly within the second threaded interconnection and extending in the axial direction from within the aluminum exit joint into the radially reduced section of the second steel casing joint such that an outer surface of the second sleeve contacts the aluminum exit joint, the second threaded interconnection and the radially reduced section of the second casing joint, thereby providing galvanic isolation between the aluminum exit joint and the second steel casing joint.