Suction caisson

Suction caissons (also referred to as suction anchors, suction piles or suction buckets) are a new form of fixed platform anchor that have a number of advantages over conventional offshore foundations, mainly being quicker to install than deep foundation piles and being easier to remove during decommissioning. Suction caissons are now used extensively worldwide for anchoring large offshore installations, like oil platforms, offshore drillings and accommodation platforms to the seafloor at great depths. In recent years suction caissons also see usage for offshore wind turbines in more shallow waters.

Oil and gas recovery at great depth could have been a very difficult task without the suction anchor technology, which was developed and used for the first time in the North Sea 30 years ago. The use of suction caissons/anchors has now become common practice worldwide. Statistics from 2002 revealed that 485 suction caissons had been installed in more than 50 different localities around the world, in depths to about 2000 m. Suction caissons have been installed in most of the deep water oil producing areas around the world: The North Sea, Gulf of Mexico, offshore West Africa, offshore Brazil, West of Shetland, South China Sea, Adriatic Sea and Timor Sea. No reliable statistics has been produced after 2002, but the use of suction caissons is still rising.

A suction caisson can effectively be described as an upturned bucket that is embedded in the marine sediment. This embedment is either achieved through pushing or by creating a negative pressure inside the caisson skirt; both of these techniques have the effect of securing the caisson into the sea bed. The foundation can also be rapidly removed by reversing the installation process, applying an over air pressure inside the caisson skirt.

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