Video: SAL Offshore: MV Annegret, Pohukura Project – Transferring Steel Jacket and Wellhead Platform

Upending the 420 tons wellhead jacket by ships cranes and a crawler crane on the quayside

7 April 2018

An old story, but still and interesting concept carried out by SAL back in 2006.

SAL was appointed by Technip to design and execute a unique transportation concept for a 420 tons steel jacket and an offshore wellhead platform. SAL provided a swivel action and outward rotation of the lifting yoke and tailing crane that turned the 56 meter long steel jacket during the lifting process.

The tailing crane also kept the structure one meter off the ground at all times. This enabled SAL to achieve a world-first in loading the complex cargo from a horizontal position into a vertical position, 42 meters out of the hatch.

The transportation from Western Australia to New Zealand took seven days, travelling on a “reduced” speed of 18 knots. SAL´s MV Annegret averaged a speed three times that of a barge.

This creates less fatigues on the structure and increased its lifespan by around ten years. The weather has been continuously monitored via satellite.

The offshore uploading of the wellhead platform and the steel jacket was completed successfully in July 2006.

MV Annegret was moored four meters from the legs of the ENSCO 56 JUR in an exercise, that has previously only ever been carried out by a barge.

Model simulations and motion analysis to predict mooring line tensions were conducted by German classification society GL and Dutch MARIN Institute.

Watch the video below: