The HETS-EP™ - External Casing Patch & Tie-Back Connection
The HETS External Casing Patch (Tie-Back) connection is an effective and long-term method of connecting new casing to a cut casing stub downhole. It provides a hydraulic and gas-tight connection capable of withstanding hundreds of tons of axial loading at well temperature, whilst maintaining the integrity and full I.D. of the original casing.
The HETS External Casing Patch (EP) connection principle is based on the elastic / plastic expansion and subsequent relaxation of metals. The HETS overshot is run over the cut casing stub in the well. The casing stub is then plastically expanded (permanently deformed) hydraulically using the HETS tool.
The tool is run on drill pipe and permanently moulds (conforms) the casing stub to the internally grooved profile of the HETS overshot using high hydraulic pressure. During this operation, the HETS overshot undergoes elastic expansion only, and therefore when the hydraulic pressure is released from inside the casing, the HETS overshot relaxes back to its original dimensions. This shrinkage is resisted by the permanently deformed casing (e.g. expanded by 5 - 9%) resulting in significant interfacial pressure between the casing and the overshot. The interference fit achieved across the grooved section provides both the metal-to-metal seal and the resistance to axial loading of the connection.
This downhole connection solution has no internal restriction and can be used for; tubing / casing repair, slot recovery, PBR replacement or as drilling (stuck casing) contingency.
Key Benefits
- Reconnects tubulars downhole
- Provides a Metal-to-metal seal
- No internal restrictions
- Full pressure integrity
- Full mechanical integrity
- Life of well connection
- Expansion tool deployed on DP or CT
- Only External Casing Patch in the world qualified to ISO 13679
