Conductor Installation Services (CIS) completed a subsea piling operation for Subsea 7 in the UK North Sea.
CIS used its remotely-operated subsea piling system, which makes it possible to drive piles as large as 42in in diameter, in water depths up to 300m. The operation was executed as part of the Cladhan Field Development, located approximately 100km northeast of the Shetland Islands. The development will eventually connect Cladhan field via a new subsea tieback to the Tern Alpha oil production platform, which lies 17.5km northeast of Cladhan field. In preparation for the tieback, CIS drove piles to secure a subsea manifold to the seabed on Cladhan field.
Following the awarding of the contract to CIS by Subsea 7 on 9 April 2015, preparation and testing began of all equipment. CIS transported the equipment to the port of Nigg in Invergordon, Scotland, loaded onto a support vessel, and, on 30 April 2015, set sail for Cladhan field to the site of the subsea pile-driving operation.
The subsea operation commenced and completed on 2 May 2015. CIS worked in a maximum water depth of 160m to drive four 24in pipeline end manifold (PLEM) piles. Each pile was driven to its target depth of 12m. The piles driven measured 16.5m from the Seven Falcon vessel, ultimately reaching a depth of 12m (39.4ft) below the mudline of the seafloor.
CIS completed the entire subsea driving operation in well under four hours.
In an effort to minimize impact on the environment, CIS uses only the highest grade of fully biodegradable oils to operate the hydraulic hammer. By doing so, in the unlikely event that any oil leaks, it disperses safely, without damaging the subsea environment.
Image: Subsea piling system/Conductor Installation Services Ltd
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