Heavy Lift Operations Floating unmanned structures dominate heavy lift order books
Liverpool Bay, Brent C, Harding, Hibernia N'Kossa heavy lifts coming in 1995
Despite the recent glut of government approvals for new developments in the North Sea, 1995 prospects appear moderate for the heavy lift brigade. In the UK, many of the projects are fast track, involving low weight unmanned or subsea structures. Floaters dominate the picture in Norway.
Crane barge owners are looking ahead a couple of years when really big platforms such as Armada and Britannia slot into place. Contractors of smaller barges are eyeing opportunities arising from the major new floater developments west of the Shetlands.
Northwest Europe
In terms of contract orders, Heeremac's DB102 dominates this season's installations, with work on seven different fields. Its largest structures are probably on Hamilton's Liverpool Bay and Shell's Brent C modules. However, the company still considers this a "bad workload". Possibly its most challenging job will come in December, when it is due to begin removal of Hamilton's Esmond and Gordon platforms.
Seaway Heavy Lifting has two moderate-sized platform installation jobs booked for Hamilton's Lennox and Conoco's Jupiter Field this summer, and has also lined up work on BP's Cleeton project in 1996. In quiet periods, the Stanislav Yudin is available for work elsewhere - preferably in winter, outside the main North Sea season, because of the time taken mobilizing the vessel to far-flung regions.
Should platform abandonment really become a pressing issue, the company feels the Yudin is ideally equipped to help out. With its minimum draught of 5.5 meters, it can dock alongside almost any fabrication quay to unload the removed structure. This technique worked well recently on Hamilton's Forbes platform abandonment.
Two of this year's more challenging specialist North Sea operations involve concrete structures. Late in January, Norwegian Contractors (NC) supervised the mating of the platform deck for Norske Shell's Troll Gas (Phase 1) project. Here Aker Stord built the deck, and NC the gravity base.
Prior to mating, the deck had been moored on top of four barges at Gronnevik quay in Vats while the GBS was moored one nautical mile away. As a first step, Aker Stord towed the deck to within 300 meters of the GBS.
Most critical phase was when the deck was passed over the top of the 369-meter base's four shafts, which were then sunk to 6.5 meters above water. The deck was manoeuvered over the shafts using four tugboats and winches. Horizontal jacks were employed to achieve a maximum misalignment of 30 mm during deck positioning.
Sheerlegs crane vessel Taklift 7 performing high lift of the Heidrun derrick tower off Norway last year.
Once the deck was in position, the concrete structure was deballasted by pumping out water from the two drilling shafts. This way, the deck's weight was gradually transferred from the four barges to the four platform legs. Then the barges were eased away, and the concrete base further deballasted until the lower face of the deck was raised 30 meters above sea level.
Hook-up of the various systems between deck and shafts is due to start by May 1995, when the platform is towed from Vats to the field.
Starting next month, Aker Marine will tow the concrete GBS for BP's Harding platform from its drydock near Glasgow, mooring it in a nearby loch. The 1,000 km tow-out and installation to the field is due in June.
Other barge operators report a busy North Sea schedule this year. Smitbarge 1, Smit Transport, Rotterdam, is booked by Saipem for a two-month charter starting April 1, for transport and installation support on Elf Enterprise's Claymore Field. Smitbarge 2 is lined up for module transport duty in May for Phillips' J-Block development. Increasingly, however, transportation specialists are looking elsewhere for work.
Newfoundland
Early last month, a Smit Maritime Contractors' project team mobilized for heavy lift assignments required during the construction of the Hibernia Field gravity base structure.
The Rotterdam-based company was awarded the two-year heavy lift contract by the Hibernia Management and Development Co. On site now at the Bull Arm fabrication centre at Trinity Cove, Newfoundland is Smit's heavy lift sheerlegs floating crane Taklift 7, along with sister barge Tak 5 and various support equipment.
Taklift will perform a series of major lifts for the project over the next two years. These include modules weighing up to 500 tons and the positioning of steel utility decks within the four main shafts of the platform. It will also be involved in placing concrete beams and plates close to the foot of the platform.
Towards the end of construction, Taklift 7 will undertake installation of the platform's flare tower and other topsides items. It will be deployed in three lifting modes: a 100-meter long boom for lifts up to 500 t; a 130-m boom for lifts up to 475 t; and a 160 m boom for those up to 335 t.
Dockwise, based in Belgium, had responsibility for transporting the Hibernia modules to Bull Arm from fabrication yards in Italy and Korea, using its Mighty Servant and Transshelf vessels. Following assembly on site of the 37,000-t topsides, Neptun Marine Contracting of Hovik, Norway, will lift, transport, and mate this structure to the GBS.
To accomplish this work, two barges will undergo modifications, probably completed next year. Neptun's Goliat 10 will be lengthened by 16.6 meters. A new 900-t deck structure will be installed, with grillage and support parts placed on top, followed by outfitting of the winching, ballast and electrical lighting system. Similar work will be performed on Anchor Marine Transportation's AMT Transporter barge, except that this vessel is being shortened, with a new 1,400-t deck structure placed on top of the old one.
The two barges will be placed under the topsides on each side of the construction pier to take the loads via a deballasting operation; then the topsides will be seafastened to the barges, which will be positioned in a catamaran configuration. Lead tugs and tractors tugs will tow the barges to the mating site, positioning the load onto the GBS via an alignment system consisting of hydraulic jacks.
Africa
Last summer, Seaway Heavy Lifting's Stanislav Yudin took time out from the North Sea to perform a subcontract installation for WEPCO's Abu Qir P1-C and P2-C platforms. The work involved transporting and installing two decks weighing around 1,000 t and four compression modules weighing around 350 t. One of the main specialists in the Africa region is McDermott-ETPM, which this year is completing two major installation programs for Elf using the jacket launch method.
Work on the N'Kossa Field off Congo is due to finish mid-year. McDermott-ETPM is responsible for platform installation in water depths of 170 meters. The two jackets, weighing 5,500 t with 4,500-t piles, will be the biggest ever installed off West Africa.
Smit Transport's Giant 2, 24,000 dwt barge.
Work on the Cobo project in 91 meters water depth off Angola is targeted for completion early December. McDermott-ETPM is to install the 4,500-t jacket, a project expected to occupy 53 barge days in addition to pipelaying and saturation diving connections. It will also install a flare tower and bridge following installation by ballasted deck of the 14,000-t deck.
Assembly of N'Kossa's concrete barge, the world's largest, is being performed at Bouygues Offshore's fabrication yard in Fos, southern France. Transportation of the modules to Fos is scheduled for July-August. Two chartered barges, along with Smit Transport's 24,000-dwt barge Giant 2, will each carry two N'Kossa modules to Fos: these will be loaded at Zwijndrecht, Ravenna and Bordeaux.
In October, another of Smit's Giant barges will transport and position the 9,650-t topsides modules COB-P1 for the Cobo project, under contract to Technip Geoproduction. Loadout will also take place at Fos.
According to Smit Transport, this will be a novel operation. The platform deck will overhang the deck of the barge. The heavy transport vessel will be positioned between the legs of the jacket, then ballasted down in a precision manoeuvre, aided by hydraulic systems, placing the topsides on the jacket. This operation is expected to take up to 48 hours.
It is an alternative approach to using a large crane barge. Technip strongly favored this option, following a successful operation offshore Alexandria in 1986, when a Giant barge replaced a deck on a jacket. However, the topsides weight was somewhat lower than for Cobo, at around 2,300 t.
Elsewhere in the world, notable jobs secured by Heeremac this year include the ACT Hz-32 platform installation off China this month; the Phillips Xijiang 30-2 platform in the same country in April (both by Hermod); and British Gas' Dolphin platform off Trinidad this September, entrusted to Balder.
| Heeremac crane barge DB102 | |
| March | Britannia drilling template (Conoco) |
| April | Schooner jacket (Shell) |
| April | Inde compression module (Amoco) |
| April/May | Liverpool Bay (Hamilton) |
| May/June | Roar/Svend/Tyra West (Maersk) |
| Summer | Markham (LASMO) |
| August | Brent C modules (Shell) |
| August | Pelican manifold (Shell) |
| August | Cormorant module (Shell) |
| December | Esmond, Gordon platform removals (Hamilton) |
| Saipem crane barge M7000 | |
| March | Andrew template (BP) |
| March | Davy, Bessemer platforms (Amoco) |
| April | Troll Oil II (Norsk Hydro) |
| April/May | Claymore accommodation platform (Elf Enterprise) |
| May | Troll Oil III (Norske Hydro) |
| June | Sleipner West B platform (Statoil) |
| Summer | Judy platform (Phillips) |
| Seaway Heavy Lift crane barge Stanislav Yudin | |
| March | Lennox platform (Hamilton) |
| June/July | Jupiter platform (Conoco) |
| August | He0wett compression module (Phillips) |
| McDermott-ETPM derrick and laybarge DLB 1601 | |
| March | K5B unmanned platform (Elf Petroland) |
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