Casing Patch and Seal

Abstract

A casing patch assembly may include a patch seal having two ring-type seals with different performance characteristics. A first ring seals against a casing patch and a casing stub. A second ring self-adjusts to the size of the casing stub and is located so that it blocks the first seal, which may be softer material than the second ring, from being squeezed into an annular gap between the casing patch and the casing stub. The second ring may include a split feature to allow for the self-adjustment. Optionally, a third ring made of a malleable material may be located between the first and second rings to protect the first ring from being damaged by movement of the split feature.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to a patch for a well casing and, more particularly, to a seal for a casing patch.BACKGROUND OF THE INVENTION[0002]Casings for wells often require maintenance and repair which involves installation of a patch at a segment of the casing. Various means for patching a well casing are known, such as those described in U.S. Pat. No. 5,829,524 to Flanders et al., entitled High Pressure Casing Patch, and U.S. Pat. No. 4,660,863 to Bailey et al., entitled Casing Patch Seal, both of which are incorporated herein by reference.[0003]A casing patch can be a tube of a certain length that is positioned at the area requiring repair due to perforation in or other damage to an existing well casing, which is also referred to as a casing string. Casing patches are installed outside and surround the well casing. The casing patch must be sealed onto the existing well casing to prevent gases, liquids, or other material from flowing into and / or ...

AI Technical Summary

Benefits of technology

[0007]In aspects of the present invention, a casing patch seal comprises a first part adapted to provide a seal between an inner tube and an outer tube surrounding the inner tube, and a second part adapted to cover a circular gap between the inner tube and a constricted p

Problems solved by technology

Many prior art seals are incapable of withstanding high pressures, such as pressures above 7,000 psi (48,000 kPa).

The seals, which are often soft and malleable to allow for a change in diameter and to ensure good contact with the casing, can extrude into the gap between the casing patch and existing casing due to pressure and / or become damaged by surrounding metal parts to such an extent that the seal leaks or fails.

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