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CIS Group completes subsea piling for Subsea 7

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Oilfield Technology,

Conductor Installation Services Ltd (CIS), an Acteon company that provides hammer services to install conductors and drive piles, has announced that it has 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 42 in. in diameter, in water depths to 300 m.

The operation was executed as part of the Cladhan Field Development, located approximately 100 km 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 17.5 km 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 four hours

The subsea operation commenced and completed on 2 May 2015. CIS worked in a maximum water depth of 160 m to drive four 24 in. pipeline end manifold (PLEM) piles.

Each pile was driven to its target depth of 12 m.

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.

About the CIS Subsea Piling System

Introduced in 2013, the CIS Subsea Piling System is operated by an experienced engineer from a control unit and monitoring system located on-board a nearby support vessel. A hydraulic hammer, connected via an electronic umbilical cable to the control system, is lowered into the water and placed directly over the subsea pile. Once it is accurately positioned, the pile is driven into the seabed by the hammer until it reaches its target depth.

Edited from source by Elizabeth Corner

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