Removal of Thrusters - Buchan Alpha

A survey was carried out to identify a suitable location for transferring personnel on and off the rig while at anchorage and a survey to identify access tower connection points once alongside the quay.

Due to draught limitations three thrusters were required to be removed to allow the Buchan to come alongside the quay for final decommissioning of the asset. Vertech mobilised a project team of 1 x Dive Support, 2 x Supervisor’s, 15 x Divers,1 x Dive Technician, and 2 x diamond wire cutting technicians to carry out the removal of the three thrusters.

The thrusters on two of the legs were of the Schottel 1500 design and it was identified that there was a flanged joint impinging the installation of the diamond wire cutting machine clamp. The flanges on both thrusters were trimmed back to allow installation of the DWCM be means of Oxy Arc Thermal cutting (Broco).

On completion of the cut on first leg the thruster was then secured to the MultiCat where the vessel then located to the quayside where the thruster was lifted onto the Quayside. The thrusters were all then removed and recovered to the quayside. A total of 80 Dives were carried out with no incident.