A Sealing Face You Cannot Repair, on a Well You Still Have to Enter

• 18¾ in Wellhead
• 3,000 psi Safe working pressure
• ROV And crane deployed
• Back-seal Tested before committing

The problem

An AX gasket seals against a machined face. Pitting on that face means no reliable seal, and until there is a seal you cannot land intervention equipment on the wellhead. Repairing the AX surface itself is possible in principle, but the outcome is uncertain and expensive to verify, and the well intervention programme sits behind it. Esso Australia came to us for tooling that would let intervention proceed on an 18¾-inch wellhead with that damage. Several concepts were investigated; a repair sleeve is the one that was developed.

What we built

The sleeve moves the lower sealing face away from the damaged AX surface and into the bore of the wellhead, which removes the requirement to repair or seal on the pitted face at all. The upper seal interface uses a modified off-the-shelf AX seal, so it can be changed out between tests and between uses rather than being a one-shot item. Several sealing locations are available along the length of the sleeve, which allows the best of them to be selected against the condition actually found in the bore.

The new bore seals are back-seal testable by ROV, so seal integrity is confirmed before landing out or mobilising well intervention equipment, rather than discovered afterwards. The bore of the sleeve is sized to pass all standard well intervention.

Sleeve and tool

If it cannot be removed

If the sleeve cannot be removed after cementing, the upper portion separates and wellhead severance proceeds as normal. The abandonment is not held hostage to the repair.

Section

Where it got to

Two sleeves and two installation tools were manufactured, and the sleeve was successfully system integration tested within the intervention connector package.

Operations Support