CIS used its remotely-operated Subsea Piling System. Through this system, piles with diameters as large as 42-in. were able to be driven in water depths up to 300 m (984 ft).
The operation was executed as part of the Cladhan field development, located approximately 100 km (62 mi) northeast of the Shetland Islands. The development will eventually connect the Cladhan field through a new subsea tieback to the Tern Alpha oil production platform, which lies 17.5 km (10.8 mi) northeast of the Cladhan field. In preparation for the tieback, CIS drove piles to secure a subsea manifold to the seabed on the Cladhan field.
The subsea operation commenced and completed on May 2, 2015. CIS worked in a maximum water depth of 160 m (525 ft) to drive four 24-in. pipeline end manifold piles. Each pile was driven to its target depth of 12 m (39 ft). The piles driven measured 16.5 m (54 ft) from Subsea 7’s dive support vesselSeven Falcon, ultimately reaching a depth of 12 m (39.4 feet) below the mudline. Operations were completed in less than four hours.
Work was carried out as a result of a contract awarded to CIS by Subsea 7 in April.