Successful 37,000ton Gas Production Topside Floatover over the NW Shelf

Offshore Weather Services provided weather forecasting services and the on board weather forecaster for the installation of the 37,000ton Chevron Wheatstone gas production topsides over the NW Shelf, Australia. Heerema Marine Contractors Nederland SE (HMC) were contracted by Daewoo Shipbuilding & Marine Engineering to bring the topsides from the fabrication yard in Korea and do the installation to the SGS (Steel Gravity Structure) that had been pre-installed (by HMC) in early September 2014.

The topsides were towed by three tugs and made good progress down the East China Sea and the east coast of the Philippines before passing through the Sulu and Java Sea on their way to the Wheatstone field. OWS provided the weather forecast services for this voyage as the vessels passed safely ahead of Super Typhoon MAYSAK over the North West Pacific Ocean and arrived at the Wheatstone location on the 08th April as another tropical cyclone (IKOLA) was dissipating 1000nm to the southwest of the site.

Peter Wellby, Offshore Weather Services Operations Manager sailed with the HMC installation engineers from Dampier on the command vessel Southern Ocean a few days before the arrival of the topsides and provided the site weather forecasts, detailed daily weather briefings and consultation leading up to the float over operation. Working closely with the HMC Marine Engineers and using sophisticated atmospheric and wave models, spectral wave analysis techniques and vessel motion simulation suitable weather ‘windows’ were determined.

The weather conditions during the actual operation were near perfect with long period W’ly swell produced a few days earlier by TC IKOLA decreasing and the prevailing SW’ly swell from the Southern Ocean at a seasonal low. Even the wind Gods were kind producing light, cooling winds that provided a comfortable working environment.

This is the third float over operation that Peter has worked closely with HMC in achieving a safe and successful operation. The other operations were the Malampaya – Shell, Philippines and North Rankin B – Woodside, Australia.

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