Swiber carries out first 'float-over' in India

Vol 16, PW 12 (10 Jan 13) Exploration & Production

After six months delay, Singapore-based Swiber Offshore has carried out India’s first ‘float-over’ installation at ONGC’s western offshore B-193 marginal oil and gas fields.

Swiber installed the 7800-tonne accommodation module onto the B-193 ‘jacket’ on December 16, followed by the 13,800-tonne process platform on December 28. Each installation took around 12 hours with around 250 technical personnel in attendance.

In a ‘float-over’ scenario barges bring ready-made modules and lower them on to the jacket by taking on seawater as ballast. This differs from typical offshore construction projects where cranes mounted on barges lift 2500-tonne topside sections and place them on a ‘jacket’ to be welded later.

No company has attempted a ‘float-over’ in India before, even though it is common globally, as calm seas are needed so the barge carrying the prefab sections can enter the space between the jacket legs. An ONGC source says a ‘float-over’ saves four to five months over using cranes.

Ironically, any time saved has been offset by the six-month delay caused by lack of equipment. ONGC awarded the $618m contract to Swiber and Malaysia-based Sime Darby in May 2010 for completion by May last year.

Sime, which manufactured the components at its Malaysian yard, blames vendors for the delay. Swiber too delayed installing the process platform, but only by a day from December 27 to 28.

“Ideally the swell (of the sea) should not be over 0.75 metres high for installation,” says ONGC. “But on December 27 the swell was over 1 metre high, forcing us to abort the installation.

” But the sea was calmer the next day, and the process platform successfully installed atop the jacket.