Galvanically isolated exit joint for well junction
A well system for forming a window in a casing string positioned in a wellbore. The system includes first and second steel casing joints ( 462, 464 ) interconnectable within the casing string. An aluminum exit joint ( 460 ) is positioned between the first and second steel casing joints ( 462, 464 ). The aluminum exit joint ( 460 ) has a first interconnection with the first steel casing joint ( 462 ) and a second interconnection with the second steel casing joint ( 464 ). The aluminum exit joint ( 460 ) is operable to have the window formed therethrough. A first sleeve ( 470 ) is positioned within the first interconnection to provide galvanic isolation between the aluminum exit joint ( 460 ) and the first steel casing joint ( 462 ). A second sleeve ( 472 ) is positioned within the second interconnection to provide galvanic isolation between the aluminum exit joint ( 460 ) and the second steel casing joint ( 464 ).
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.
2. The casing string as recited in claim 1 further comprising a first nonconductive layer positioned within the first interconnection preventing metal-to-metal contact between the aluminum exit joint and the first steel casing joint and a second nonconductive layer positioned within the second interconnection preventing metal-to-metal contact between the aluminum exit joint and the second steel casing joint.
3. The casing string as recited in claim 1 wherein the first and second sleeves are formed from a nonconductive material.
4. The casing string as recited in claim 3 wherein the nonconductive material is selected from the group consisting of polymers and fiberglass.
5. The casing string as recited in claim 1 wherein the first and second sleeves further comprise a wear resistant material.
6. The casing string as recited in claim 5 wherein the wear resistant material is selected from the group consisting of tungsten and ceramics.
7. 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; and
a sleeve positioned interiorly within the aluminum exit joint and extending in the axial direction from within the aluminum exit joint through the first threaded interconnection into the radially reduced section of the first steel casing joint and through the second threaded interconnection into the radially reduced section of the second steel casing joint such that an outer surface of the sleeve contacts the aluminum exit joint, the first and second threaded interconnections and the radially reduced section of the first and second casing joint, thereby providing galvanic isolation between the aluminum exit joint and the first and second steel casing joints.
8. The casing string as recited in claim 7 further comprising a first nonconductive layer positioned within the first interconnection preventing metal-to-metal contact between the aluminum exit joint and the first steel casing joint and a second nonconductive layer positioned within the second interconnection preventing metal-to-metal contact between the aluminum exit joint and the second steel casing joint.
9. The casing string as recited in claim 7 wherein the sleeve is formed from a nonconductive material.
10. The casing string as recited in claim 9 wherein the nonconductive material is selected from the group consisting of polymers and fiberglass.
11. The casing string as recited in claim 7 wherein the sleeve further comprises a wear resistant material.
12. The casing string as recited in claim 11 wherein the wear resistant material is selected from the group consisting of tungsten and ceramics.