The North Sea s Biggest Decommissioning Programmes

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The North Sea’s biggest decommissioningprogrammes

8 August 2012 |www.offshore-technology.com

The North Sea will witness a hike in decommissioning programmes during the next twodecades as oil and gas infrastructure mature. From the Shelly field to North West Hutton,offshore-technology lists past and present decommissioning programmes on the UK Continental Shelf (UKCS).

Several oil and gas structures in the North Sea are reaching the end of their designlifespan and it's time for them to come down.

To ease the process and clear some of the confusion surrounding the North Sea, the UK Government earlier this year published a consultation which will clarify the levels of taxrelief on decommissioning costs oil and gas companies will receive.

Not due until 1 October 2012, it is hoped that the consultation will remove major fiscal

risks for North Sea investors and possibly release significant funds by allowingcompanies to move to post-tax decommissioning guarantees.

With this, and additional government backing through the signing of contracts, the next20 years are expected to see an influx of decommissioning programmes.

Here, we list some of the North Sea oil and gas projects proposed to go offline over thelast decade.



Premier Oil Shelley field

The Shelley field is located on Blocks 22/2b and 22/3a in the central North Sea

The UK Department of Energy and Climate Change approved the decommissioning of the FPSO, manifold and wellheads located in the Premier Oil-operated Shelley field in2010.

Since production began, the performance of the Shelley wells has not met expectations.According to Premier Oil, the reservoir pressure fell significantly and the proportion of

water in produced fluids rose much earlier than expected.

The Shelley field is located on Blocks 22/2b and 22/3a in the central North Sea, about192km east of Fraserburgh, Scotland. The facilities in the Shelley field comprised of twoproduction wells with Xmas trees and a subsea production manifold and protectionstructure.

These were tied back to the Sevan Voyageur FPSO by a 2.02km production pipeline anda 2.42km trenched electro / hydraulic control umbilical.

Technip secured a contract worth around £4.4m to decommission the Shelley field in

June 2011 and a close out report was received in February 2012.



Brent field

In 1998, the company chose to reuse the spar as a Norwegian Ro/Ro ferry quay atMekjarvik

According to Oil and Gas UK, the Brent Spar, a storage and tanker loading buoy, wastaken out of service in 1991 after around 15 years of service in the Shell / Esso Brentfield in the Northern North Sea - the UK's largest source of oil and gas.

Studies at the time suggested that the Spar should be disposed of at a deepwater site in

the Northern Atlantic, but protests from environmental groups forced Shell to abandonthis plan. In 1998, the company chose to reuse the spar as a Norwegian Ro/Ro ferry quayat Mekjarvik.

Shell also began a programme in 2009 to abandon redundant wells on the Brent Deltaplatform prior to cessation of production. So far, wells plugging and abandoning workhas started on Brent Alpha and Delta platforms.

The Brent Delta decommissioning services contract was awarded in 2010 to Wood GroupPSN and the tender process for contracts for the topsides removals and onshoredismantling of the Brent platforms is progressing, with award planned for the first half of

2013.



Frigg field

The Frigg field ceased production in 2004 after 27 years of service

The Frigg field, located between the continental shelves of the UK and Norwegianborders in North Sea, ceased production in 2004 after 27 years of service.

After all wells were plugged and abandoned, Aker Kvaerner Offshore Partner (now AkerSolutions) was contracted to remove all six installations at the field, including thedamaged drilling platform one (DP1).

Both the Norwegian and UK governments agreed to clean up and remove the structureson the field except for the gravity base structures of concrete DP1, treatment platform oneand treatment compressing platform two.

About 85,000t of steel was removed from the Frigg field and the manifold compressionplant between 2005 and 2008. Of this, 20,000t was taken to Shetland for dismantling andthe remaining to Stord. All the steel was recycled.



North West Hutton field

In 2002 - 19 years after production began - the UK Government ordered the field to betaken out of service

The North West Hutton field is located 130km north-east of the Shetland Islands in Block211/27a in the UK North Sea. It is situated at a water depth of 143m and was discoveredin 1975 by the Amoco Group.

In 2002 - 19 years after production began - the UK Government ordered the field to be

taken out of service after it was declared that no more reserves could be recovered fromthe area.

Following a consultation by the Convention for the Protection of the Marine Environmentof the North-East Atlantic, the Department of Trade and Industry approved thedecommissioning programme for the North West Hutton installations in 2006.

The programme requires that topsides and steel jacket are removed and recycled onshore;the jacket footings are left in place, including the piles which fix the structure to the seabed; the drill cuttings pile to be left in place to allow the seabed to recover naturally; theoil pipeline to be trenched and buried; and the gas pipeline, which has already been

trenched, left in place.



Ekofisk area development

Decommissioning of the other 14 structures and the Ekofisk Tank topsides at Ekofisk Ibegan in 2005/2006

The original Ekofisk area development consisted of eight oil and gas fields, namely Cod,Ekofisk, West Ekofisk, Tor, Albuskjell, Eldfisk, Edda and Embla.

In December 1993 Phillips Norway submitted a £2.1bn expansion plan to bring oil andgas to market until 2028. This envisaged refurbishing platforms 2 / 4C, 2 / 4Q, 2 / 4FTP

and 2 / 4W and constructing two new platforms at the Ekofisk complex.

At the same time, the Ekofisk 1 Cessation project was launched with the objective of achieving the disposal of the field's northern structures in a cost-effective andenvironmentally friendly manner.

Decommissioning of the other 14 structures and the Ekofisk Tank topsides at Ekofisk Ibegan in 2005/2006 and are scheduled to continue until 2013. Heerema MarineContractors were awarded the contract for the removal of bridges, bridge supports andflares using heavy lift vessels.

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The North Sea s Biggest Decommissioning Programmes