Black Marlin completes semisub floatover

Dockwise has completed the first of two float-overs for the new Vyborg semisubmersible drilling rigs project.

Offshore staff

BREDA, the Netherlands -- Dockwise has completed the first of two float-overs for the new Vyborg semisubmersible drilling rigs project.

The $100-million project involved nearly two years of engineering, procurement, and project preparations.

Dockwise’s task was to transport and mate two 15,000-metric ton (16,535-ton) semisubmersible hulls and two topsides, each weighing around 19,000 mt (20,944 t). These structures were constructed in locations over 27,000 km (16,777 mi) sailing distance apart.

For the first rig, the Black Marlin transport vessel was used to load one of the two topsides for transport to the float-over location in South Korea, where it would be mated with a hull shipped from Vyborg, northwest Russia by the Talisman.

Dockwise also was responsible for designing and installing the pre-laid anchor spread, hooking the hull to this spread, then ballasting the hull to its mating draft. This program involved a spread of five tugs, two anchor handler vessels, one workboat, two anchor barges, one test barge, a crane barge, three launch boats, and guard boats.

Float-over was completed without a fixed structure – instead, a floating structure was anchored and ballasted down to secure it in place while Dockwise performed the float-over.

After the Black Marlin docked into the hull, which was ballasted down to 27 m (88.6 ft) draft, ballasting was performed in order to lock the leg mating units and align the hull columns and the topside.

Next, the columns were welded to the topside under a partial load transfer, after which the load was released from the leg mating units. Then further ballasting was conducted in order to transfer the full load of the topside onto the hull columns.

On July 10, the Black Marlin was pulled back from the mated rig. De-ballasting operations should be completed over the next few days. The second topside and hull will be mated using the same procedures later this fall.

07/12/2010

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