PIPELINES Norwegian gas expansion schemes dominate pipelayers' workload

Coflexip Stena Offshore's Apache loading out a dynamic flexible riser at Le Trait, France. Pipelayers are habitual pessimists, worried about gaps in their schedules five years ahead. In Northwest Europe, they will have to console themselves with exceptionally healthy short-term order books. Best placed are the large diameter line crowd, thanks to a series of major new gas projects sanctioned by the Norwegian parliament last year. But the smaller diameter and intra-field flowline



Coflexip Stena Offshore's Apache loading out a dynamic flexible riser at Le Trait, France.

Pipelayers are habitual pessimists, worried about gaps in their schedules five years ahead. In Northwest Europe, they will have to console themselves with exceptionally healthy short-term order books.

Best placed are the large diameter line crowd, thanks to a series of major new gas projects sanctioned by the Norwegian parliament last year. But the smaller diameter and intra-field flowline specialists are also active, due to an upswing in medium size and subsea developments off the UK this year.

Leading the field at the heavy end is McDermott-ETPM West. Following a lean year in the North Sea, the US/French venture has been booked to lay the Norwegian gas export network's largest trunkline to date, NorFra.

The 40-inch diameter, 860 km line willl extend from the 16/11-E complex riser platform to Dunkirk in northern France. The termination point was specified by Gas de France, which has contracted 40 bcm from Norway's gas developers, commencing 2001.

NorFra could, however, be operating by October 1998. Laying should start this year, performed by the LB200 barge, with ETPM 1601 handling operations next year. The pipeline willl shadow the route of the Zeepipe I line into Dutch and Belgian waters before veering southwest for Dunkirk.

This season LB200 willl also install the 298 km line linking the Troll gas processing centre at Kollsnes to 16/11-E, as part of the Zeepipe IIB project. McDermott-ETPM West willl also handle the Haltenlink installation for Statoil: this willl be a 450-500 km, large diameter line carrying gas from the Aasgard Field in the Haltenbanken. At time of writing, a landing point on west Norway had not been fixed, but Kollsnes or Karsto were the likely options.

Prior to all these duties, the pipelay contractor has a shorter, but not routine assignment to install the 30 km, 16-inch multiphase gas/condensate line between the Erskine and Lomond platforms. Texaco-operated Erskine is the UK's first HP/HT reservoir, with in-line temperatures set to reach 150intergralC.

ETPM is designing an insulation system to prevent cooling of the pipeline's cargo and consequent wax/hydrate formation (it has prior experience installing such a line for Total's Dunbar-Alwyn North link). Erskine's output willl be processed at Lomond before transferring onwards to the CATS and Forties export systems.

Last year EMC hogged most of the major pipelay jobs off Norway: the Troll Oil-Mongstad line, the 300 km Kollsnes-Sleipner East link (Zeepipe II) and the 245km Haltenpipe line from Heidrun Field to Tjeldbergodden. Finishing touches are being applied to Haltnepipe, which willl have capacity of up to 4.5 bcm/year, allowing for future tie-ins from Draugen and other Haltenbanken fields.

EMC's main upcoming Norwegian work relates to the Ekofisk II redevelopment. Here a new wellhead platform is being installed, followed by a new processing/riser platform, 2/4-J, due to start operating in 1998. To this willl be directed oil and gas from the Ekofisk, Eldfisk, Embla, Gyda and Valhall Fields.

Six different oil and gas pipelines and flowlines willl be laid for the project this summer by EMC, totalling over 50 km in length. Allseas has been booked to lay a separate loop line around the Ekofisk central complex, using its giant new dynamically positioned vessel Solitaire. Despite the recent termination of Sembawang's construction contract, the vessel willl be completed by another yard in time to start the Ekofisk bypass work in spring 1997, says Allseas.

The new Ekofisk lines willl cross over existing pipelines at 57 points. Laying operations must also take into account Ekofisk's infamous seabed subsidence, which threatens horizontal as well as vertical displacement of the platform. As a solution, spool pieces up to 71 metres long willl be fitted to the new lines, acting as an expansion joint to allow for lateral offset and horizontal shift. To accommodate these spool pieces, pipeline corridors to 2/4 J have been created.

The new lines willl also be buried and covered with rock in places to suppress horizontal movements. A worst case scenario suggests that the Ekofisk oil line to Teesside, UK could move up to 3.1 metres towards the 2/4-J riser platform.

Still in Norway, once NorFra has been installed, Allseas' Solitaire should begin work on the 600 km, 40-inch diameter Europipe II gas export line, which willl follow the route of Europipe I (completed in 1994) from 16/11-E to Norderey in Germany. The three-mile land approach section for Europipe II is already in place.

Over the next five years these new gas export lines, over 2,500 km in total, willl virtually double Norway's gas export capacity to 50 bcm/year. Clamour for gas from Continental Europe utilities has made it possible, but falling installation costs and improved steel purchasing deals have helped. Statoil claims a new line can now be laid at 40% of the cost of the Statpipe trunkline a decade ago.

Statoil also aims to reduce operating expenditure for these lines. This is one of the targets for Halliburton Oilfield Services Norway, recently awarded a five-year commissioning contract for all Statoil pipelines, including the new Sleipner Vest and NorFra lines.

Interconnector delay

Long distance pipelines are not a priority for UK operators currently. The exception is the proposed 215 km Interconnector gas link from Bacton to Zeebrugge: selected contractor EMC hopes to start installation work this year, even though the UK landfall site has been vetoed by the North Norfolk District Council for a host of environmental reasons. Definitely next year, EMC willl lay the 195 km, 26-inch gas export line from the Britannia platform to the SAGE terminal at St Fergus.

Otherwise, apart from Elf's Elgin/ Franklin and Shell's Shearwater/Puffin (which may share one export system tying into the Interconnector), there is little substantial to bid for. In remote North Sea areas where export infrastructure is lacking, developers are increasingly favoring floaters with tanker offloading.

However, there is a steady stream of shorter pipeline installation jobs in the UK and Norway. Contractors traditionally reliant on North Sea work have anyway overcome troughs in demand by selling their services overseas, or by adapting their vessels to handle both steel and flexible pipelay.

An example is Coflexip-Stena Offshore's (CSO) Apache, now a regular winter fixture for Petrobras in Brazil. At the end of March it returns to the UK to install a line for Texaco's Captain development. Then in June it heads for Norwegian block 34/6 to lay oil lines between Saga's Vigdis Field and the Snorre TLP. The flowlines have been produced at CSO's new spoolbase in Orkanger, south of Trondheim. Apache should also perform reel laying on Telford, Amoco's subsea tieback to the Scott platform, under subcontract from Rockwater.

Another globetrotting CSO vessel, co-owned with Ugland, is the Flex Installer, which willl leave Amoco's Liuhua Field in China in May for infield pipeline installation on Statoil's Norne development.

Allseas' Lorelay looks to have the most cosmopolitan schedule. Assuming its work on the Centana Field in the Gulf of Mexico is finished, it moves to the North Sea for the 28 km Shell Schooner - Conoco Murdoch link; Arco Trent/Tyne inter-platform pipeline, plus tie-ins to the Esmond trunkline system; and Vigdis for the 31 km oil export line between the Snorre TLP and Gullfaks A.

Thereafter Lorelay is booked for work on Sleipner Vest (where its Phoenix automatic welding system willl be used on duplex line); to Denmark for the 77 km, 24-inch line between the Tyra East F and Harald West A platforms for Maersk (crossing four telephone lines); and back to the UK for service on Shell's Fulmar and Amoco's subsea Arkwright project.

In autumn it returns to the Gulf for Shell's Ram Powell and Mensa: the latter will be a 101 km oil export line in water depths down to 1,650 metres, including a PLEM installation at the deep end. Next year's bookings include the Poseidon project for Repsol in the Gulf of Cadiz, Spain, where Lorelay willl lay a 24 km trunkline and two flow lines carrying gas between the Poseidon North and South Reservoirs and a processing plant 500 metre inshore. Allseas willl also engineer the landfall. Trenchsetter is supporting Lorelay on most of these projects.

Among the other contractors, Stolt Comex Seaway is upgrading the Seaway Falcon for flowline and gas lift line installation this spring between Statoil's Yme platform and the small new oil satellite Yme Beta East.

The joint venture with Land & Marine Engineering, Costain-Stolt, willl perform the 15 km tie-back from the subsea centre to the platform on the Britannia Field. Two 7.5 km pipeline/umbilical bundles willl be installed in series. Elsewhere, SubSea Offshore's dsv Discovery willl install flexible flowlines and umbilicals from Mobil's Beryl A riser access tower to the new Nevis South complex.

Outstanding pipelay awards are mainly in Norway: the Aasgard interfield oil and gas lines, the Gullfaks satellites pipeline network, and Visund. According to Scanboss, Visund operator Norsk Hydro is pressing for a 20-inch oil line from the field's semisubmersible production unit to Gullfaks 27 km away.

There may also be a flurry of activity, for once, in Germany where Aker Engineering is conceiving a possible oil and gas line from a new Wintershall discovery in block A6/B4. This could be tied back from a new wellhead platform to Amoco Norway's Valhall platform 45 km away.

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