CIS Group completes subsea piling operation for Subsea 7
Conductor Installation Services (CIS), an Acteon company that provides hammer services to install conductors and drive piles, announced that it successfully 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 42inch in diameter, in water depths 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.
“This operation on Cladhan field for Subsea 7 was the first time that the company had commissioned a subsea operation from CIS to use our remotely-operated Subsea Piling System,” said Andy Penman, Group Managing Director of CIS. “We are very pleased that it performed reliably, and that the operation was completed ahead of schedule.”
Rapid response
Work was carried out as a result of a contract awarded to CIS by Subsea 7 on 9 April 2015. Following preparation and testing of all equipment at its base in Great Yarmouth, England, CIS transported it to the port of Nigg in Invergordon, Scotland. On 28 April 2015, it was loaded onto the support vessel, from which CIS would carry out the subsea piling operation remotely. In the early hours of 30 April 2015, the crew set sail for Cladhan field to the site of the subsea pile-driving operation.
Subsea piles driven in just 4 hours
The subsea operation commenced and completed on 2 May 2015. CIS worked in a maximum water depth of 160m to drive four 24-inch 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 (39.4 feet) below the mudline of the seafloor.
CIS completed the entire subsea driving operation in well under four hours.
Kind to the environment
In an effort to minimise 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. In addition, the fact that the Subsea Piling System is controlled automatically means that it takes less time to deploy and operate the hammer, making it that much more efficient.