Shell, Norsk Hydro keep platform builders in business

Within days of approval being secured for the Elgin/Franklin development, the UK North Sea's outstanding HT/HP gas condensate project also gained clearance. Shell Expro's Shearwater Field, located in Central block 22/30b adjacent to Elgin/Franklin, will be brought onstream by mid-2000 at a cost of E714 million.

Shearwater was first discovered by Arco in 1988 when semisub Ocean Odyssey suffered damage from a blow-out. Shell assumed operatorship in 1991, continuing the appraisal programme. The platform, to be located in 295 ft of water, will produce up to 410 mcf/d of gas and 90,000 b/d of condensate.

Gas will be sent through a new 34-in., 463 km pipeline to Bacton, funded by the Elgin/Franklin and Shearwater co-venturers at a cost of #400 million. Elf will be the operator during construction, with Shell Expro taking over once the fields start producing. Shearwater's liquids will be directed to Grangemouth, Scotland through a new 24-in. spur line into a Y-piece, located near the Marnock platform, to the ETAP pipeline.

Production facilities for Shearwater are being developed by an alliance involving Shell Expro, Amec and Heerema. These two fabricators will design, build and install the central processing platform and topsides for the wellhead jacket. Most of the work will be performed at sites on Teesside and Tyneside, UK with the main platform substructure built by Heerema at Vlissingen. SLP Engineering Teesside is building the four-leg, 2,500t wellhead jacket.

Recoverable reserves from the field are put at 844 bcf and 159MM bbl. The HP/HT reservoir is situated 16,000 ft below the seabed, necessitating drilling of deep development wells prior to the production start. This will be handled by a well engineering alliance formed by Shell Expro with Maersk Drilling. Jack-up Maersk Endurer, currently being refitted in the USA for HP/HT duty, will start the work this August. The nine-slot wellhead jacket will be installed shortly, acting as a template for the drilling operations.

The main production platform will comprise a 10,600t integrated deck, 1,600t compression module, flare tower and 78-man accommodation module, all resting on a conventional 6,000t, four-leg jacket. This should be installed in summer 1999, bridge-linked to the wellhead platform 80 metres away. There will be no processing facilities on the wellhead structure. Each flowline will be combined into a common production manifold and piped across the bridge to the primary separator on the processing platform.

Barring further discoveries in the midwater depths of the North Sea, Shearwater may be one of the last of the UK's giant platforms. The only other remaining contenders are Clair and Alba South, but these could also go the way of subsea or floating production.

Oseberg expands

Norsk Hydro, however, believes that platforms are still viable for Norway. It has issued letters of intent for two EPC contracts for the deck and jacket for Oseberg South, as well as hook-up operations. Water depth is 100 metres.

The contracts are subject to planning permission for the development, costed at NKr7.6 billion, which aims to recover 53.5 mcm of oil and 11 bcm of gas.