Remove the rig 24,000 tons in a few seconds

The Dutch energy company Shell has announced that it has found a solution to dismantle the floating portion of the 24,000-ton Brent Delta rig by a single lift method in seconds.

Amazingly, the 24,000-ton rig is removed in a few seconds

Brent Delta is a project in the system of 4 rigs Bravo, Alpha, Delta, Charlie of Brent oil field in the North Sea, Atlantic Ocean. This rig has been operating for 35 years. In 1982, each day the rig supplied more than half a million barrels of oil, the total annual output was enough to meet the demand for half of the UK households.

Delta rig off the North Sea.(Photo: Shell)

So far, Brent oil field has become old so Shell intends to dismantle and rebuild the project. But this is not simply due to the massive structure of the rig and the harsh environment in the North Sea.

According to Shell's statistics, the floating part of the rig is 44 m high, weighs 24,000 tons including 10 tons of asbestos (used for insulation and cushioning), 899 tons of paint, 31 tons of battery, 6 tons of cotton for lining and 3446 Fluorescent tube. This is a part of the building including assembly blocks, helipad and other operation areas.

Pioneering Spirit is the world's largest construction and installation ship, Allseas, Switzerland. The ship is 382m long, 900,000 tons of displacement, worth 1.7 billion USD.

Allseas said, Pioneering Spirit has a maximum lifting weight of 48,000 tons. To lift the rig, the ship will be assembled with 16 beams of 65 m long. After approaching the rig, Pioneering Spirit will put the hydraulic clamp on the bearing points under the rig, then pump the water out of the ballast tank to lift the floating part of Delta. This process only takes a few seconds.

Compare the height of the Delta rig with other buildings.(Graphic: BBC)

' This is the first ship so far capable of removing the floating part of a rig of such a size in one lift.' Alistair Hope, director of the Brent rig dismantling project, Shell said. The purpose of cooperation between Shell and Allseas is to use Pioneering Spirit to dismantle the rig safely and creatively.

"Analysis shows that, in the harsh environment of the North Sea, a single lift ship needs to be equipped with a motion compensation system to eliminate the impact of waves on the floating part, " Allseas website writes claims the Pionerring Spirit can lift the rig from 3.5 m high waves.

'If this system is lacking, local damage can occur even if the wave is not high and the ship's movement is also limited'.

Shell considered two other options before choosing a one-time lift solution. The first option is to cut the floating part of Delta into pieces of 10-100 kg and move it to shore. Option 2 is to cut and remove each module in reverse order of the installation step.

Shell believes that a one-off method will save time, cut costs and reduce the risk of affecting the environment.

' There is still risk, but generally lifting the rig in one time is the safest way for employees and the least damaging to the environment.' The BBC quoted Lang Banks, director of the Nature Protection Fund. International (WWW) Scotland.

"The biggest challenge, however, is how to deal with the submarine foundation, including thousands of tons of steel, concrete and drill bits ," Banks said.

If successful Pioneering Spirit will work with the remaining 3 rigs at Brent is Bravo, Charlie and Alpha . Meanwhile, the biggest project that Pioneering Spirit is about to implement this year is to remove the smaller Brent platform, Yme, in the center of the North Sea, 100 kilometers from the Norwegian coast.