Remediation of Wellhead to Re-establish Annulus Outlet

Claxton restored safe annulus access with a precision-engineered solution that reduced risk, protected wellhead integrity and kept decommissioning moving

The Challenge

When trapped annulus pressure and an inoperable annulus valve threatened progress, the client needed more than a workaround— they needed a proven partner that could restore access safely, protect wellhead integrity and maintain momentum on a complex decommissioning programme. With hot tapping, low-pressure risers and MGRT (Marine Growth Removal Tool) operations all in scope, the challenge called for specialist engineering, disciplined execution and absolute confidence in safety-critical delivery.

The Solution

Claxton delivered a bespoke, fully controlled solution to restore annulus access without compromising wellhead integrity.
• Verified wall thickness in-house to confirm structural suitability.
• Drilled and tapped the wellhead with a 2” LP Thread to allow install of a new annulus value, then installed an inhouse design and manufactured bespoke crossover 5k flange and two API-compliant gate valves.
• Hot tapped through the assembly to re-establish annulus communication and enable controlled bleed-down.

The Result

Claxton restored annulus access safely, enabled full depressurisation and kept decommissioning on track.
• Restored annulus communication through two gate valves.
• Secured valve isolation without incident.
• Safely bled down trapped annulus pressure.
This project shows how Claxton combines in-house engineering expertise, precision machining via Probe Manufacturing and the supply of specialist equipment and disciplined execution to solve complex wellhead challenges and keep critical decommissioning work moving.

Wellhead aspect ratio 31 — Retrofit annulus valves fitted to casing head, post hot tap

Drilled hole scaled aspect ratio 31 — Wellhead Tapped - 2" Line Pipe Thread

One Annulus outlet reinstated on wellhead system
105mm Of steel passed through by Hot Tap Casing Head
3,000 psi SWP Hot Tap Equipment rated to