Self-expandable cylinder in a downhole tool
View Patent ↗A self-expandable cylinder insertable into the bore of a downhole tool includes a resilient material rolled into a substantially cylindrical shape. The outside circumference of the self-expandable cylinder is variable to allow the self-expandable cylinder to be inserted into a narrowed bore of the downhole tool near the box end or pin end. Once past the narrowed bore, the outside circumference of the self-expandable cylinder self-expands within the bore of the downhole tool. The outside circumference of the self-expandable cylinder may expand to contact the inside surface of the bore. In selected embodiments, a transmission line may be routed between the bore and the outside circumference of the resilient material. The self-expandable cylinder may be effective to protect the transmission line from materials traveling through the bore.
1. A downhole tool, comprising:
a bore wall comprising an inside circumference and a first electrical potential;
a self-expandable cylinder comprising a second electrical potential;
the self-expandable cylinder being disposed within and constrained to the inside circumference of at least a portion of the bore wall,
and a mechanism for protecting the bore wall from the electrical potential of at least a portion of the self expandable cylinder;
wherein the mechanism for protection of the bore wall comprises an electrically insulating coating on the outside surface of the self expandable cylinder wherein the mechanism comprises a greater uncoated surface on the bore wall in electrical contact with a lesser uncoated surface on the self expandable cylinder.
2. The downhole tool of claim 1 , wherein the self expandable cylinder is constrained to a circumferential length less than its self expandable length.
3. The downhole tool of claim 1 , wherein the self expandable cylinder is constrained to a circumferential length at least as great as its self expandable length.
4. The downhole tool of claim 1 , wherein the bore wall comprises one or more constrictions.
5. The downhole tool of claim 1 , wherein at least a portion of the self-expandable cylinder is deformed in situ to match the constrictions in the bore wall.
6. The downhole tool of claim 1 , wherein the self-expandable cylinder is preformed to approximate the constrictions in the bore wall.
7. The downhole tool of claim 1 , wherein at least a portion of the self-expandable cylinder is in electrical contact with at least a portion of the bore wall.
8. The downhole tool of claim 1 , wherein the self-expandable cylinder has a wall thickness of between about 0.1 mm and less than about 2.0 mm.
9. The downhole tool of claim 1 , wherein the mechanism for protecting the bore wall comprises the first electrical potential and the second electrical potential being within overlapping ranges as measured on the seawater Galvanic Series.
10. The downhole tool of claim 1 , wherein the mechanism for protecting the bore wall comprises the first electrical potential and the second electrical potential being not within overlapping ranges on the seawater Galvanic Series.
11. The downhole tool of claim 10 , wherein the mechanism for protecting the bore wall comprises an average difference between the electrical potential of the bore wall and that of the self-expandable cylinder being less than about 1.9, preferably less than about 1.5, and more preferably less than about 0.5, but greater than about 0.1, as measured on the seawater Galvanic Series.
12. The downhole tool of claim 1 , wherein the mechanism for protection of the bore wall comprises the bore wall being less active than the self-expandable cylinder as measured on the seawater Galvanic Series.
13. The downhole tool of claim 1 , wherein the bore wall is more active than the self-expandable cylinder as measured on the seawater Galvanic Series.
14. The downhole tool of claim 13 , wherein the mechanism for protection of the bore wall comprises one or more materials more active than the bore wall and the self-expandable cylinder as measured on the seawater Galvanic Series being disposed in electrical contact with the bore wall and the self-expandable cylinder.
15. The downhole tool of claim 13 , wherein the mechanism for protection of the bore wall comprises one or more materials more active than the bore wall and the self-expandable cylinder as measured on the seawater Galvanic Series being disposed within recesses about the exterior of the downhole tool.
16. The downhole tool of claim 13 , wherein the mechanism for protection of the bore wall comprises one or more materials more active than the bore wall and the self-expandable cylinder as measured on the seawater Galvanic Series being disposed intermediate at least a portion of the bore wall and at least a portion of the self-expandable cylinder.
17. The downhole tool of claim 13 , wherein the mechanism for protection of the bore wall comprises one or more preformed materials more active than the bore wall and the self-expandable cylinder as measured on the seawater Galvanic Series being disposed intermediate at least portion of the bore wall and at least a portion of the self-expandable cylinder.
18. The downhole tool of claim 13 , wherein the mechanism for protection of the bore wall comprises an electrical insulating barrier disposed intermediate the bore wall and the self-expandable cylinder.
19. The downhole tool of claim 1 , wherein the mechanism for protection of the bore wall comprises a coated outside surface of the self-expandable cylinder being in contact with an uncoated surface of the bore wall.
20. The downhole tool of claim 1 , wherein the mechanism for protection of the bore wall comprises an electrically insulating coating on the bore wall.
21. The downhole tool of claim 1 , wherein the self-expandable cylinder comprises a seal intermediate mating ends of the self-expandable cylinder.