Spar fabrication talks underway for Brazil and West Africa sites

Spar fabrication speed picking up with experience

Jul 1st, 1999
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Aker's Mantyluoto fabrication facility in southwest Finland is shown with the first section of the Diana Spar hull set to leave for the Gulf of Mexico.
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Finland's Aker Rauma Offshore is best known today for its manufacturing role in establishing the Spar platform as a prime option for deepwater oil and gas production. It was not an easy task. Rauma Offshore has worked with Deep Oil Technology of Houston since the mid-1980s, and it required several years to convince leading operators of the benefits of the Spar concept.

The company's other major interest at present is the construction and upgrading of drilling rigs, particularly for use in the Caspian Sea. Alliances with fabrication yards in Russia and Azerbaijan have played a large part in securing Aker Rauma's leading position in this market sector.

The cautious stance adopted by the major operators following last year's oil price collapse has served to halt, at least for the time being, the production line for Spar platform hulls. The hulls are fabricated at Aker Mantyluoto in Pori, Finland. The yard, which is at the forefront of this particular floating production technology, has built three deepwater production Spars in succession. However, while discussions are being held with a number of operators, there are no plans to commence fabrication of a fourth such structure.

The second section of Aker's latest Spar, destined for Exxon-Mobil's Hoover and Diana field developments in the Gulf of Mexico, left the yard on its 23-day voyage to Aker Gulf Marine's Corpus Christi facility in Texas late in May. Mating with the other half of the structure, which made the same journey from Finland in February, is expected to be completed in time for delivery of the complete Spar hull to Exxon-Mobil in October.

"This is the third Spar that we have built, and with each one we have improved our productivity," says Jarmo Eerola, Sales Manager for Aker Rauma. The 32 meter diameter Diana Spar, weighing over 32,000 tons, was fabricated in 18 months, and the final section left the yard a week earlier than planned. Eerola points out that the previous Spar built at Mantyluoto for Chevron's Genesis development, which was slightly smaller at 25,000 tons, took 21 months to complete.

"The improvement was the result of process streamlining and also the involvement of more subcontractors on this latest project," Eerola explains. "Sharing the fabrication of some of the internal sections hastened the work considerably. However, we had to take extra care that safety and quality performance did not suffer as a result. Effective project management was crucial here. As it turned out, we experienced fewer lost time incidents per million man-hours worked than on the previous Genesis project. Further more, we managed to exceed the quality standards laid down by the client."

Aker Rauma had hoped that a fourth Spar would now be taking shape in Pori for BP Amoco's King Field in the Gulf of Mexico. Front-end engineering for a truss Spar - where the bottom part of the structure is in the form of an open steel lattice rather than a cylinder - was undertaken during 1998. However, BP Amoco has placed the development on hold for the time being, a decision thought to be based simply on the uncertainty surrounding the oil price.

Despite this disappointment, Eerola remains optimistic. "If the recent oil price rise is sustained, I think we will certainly regain our momentum next year." Another reason for confidence is that Aker has received serious inquiries from several other operators influenced by the success of the Chevron Genesis and earlier Oryx Neptune projects. The company is currently performing front-end engineering for clients with potential developments off Brazil and West Africa. Eerola cannot disclose details at this stage, but does admit that conventional Spars are being considered in both cases.

Caspian rigs enter service

Deepwater Spars account currently for around 40% of Aker Rauma's business. The remainder comes mainly from the conversion and upgrade of drilling rigs, with particular focus on the market in the Caspian.

Bilateral trade agreements between Finland and the Former Soviet Union helped Rauma Repola - as it was before the takeover by Aker in 1995 - to build a strong presence in this market during the late 1970s. The company delivered its first semisubmersible drilling rig, the Dada Gorgud, to the Caspian in 1978. Early structures were designed to be fabricated in sections, transported via canal into the Caspian and then assembled.

A key factor in Aker Rauma's success in this region has been the formation of strong alliances with fabrication yards along the shores of the Caspian. Under one such venture, the company completed construction of the semisubmersible drilling rig Istiglal at the Zykh II yard in Baku last December. The rig is working currently for BP Amoco on the Shakh Deniz prospect.


Parker Drilling's Rig 257 at the Morskoi Zavod yard in Astrakhan. Aker Rauma has collaborated with this yard for the past few years.
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Another contract is Parker Drilling's Rig 257 at the Morskoi Zavod yard in Astrakahan, Russia on the northern Caspian coast. Completion is imminent and the barge is set to drill offshore in the seasonally ice-locked and environmentally sensitive northern Caspian in just 20 ft water depth. The customer is a consortium consisting of Shell, Statoil, BP Amoco, BG, Mobil, Total, Agip, Phillips, and Inpex.

Aker Rauma also has recently completed the upgrade of the drilling rig Astra - formerly the Marawah - in partnership with the Krassnye Barrikady fabrication yard in Astrakhan. The company transported this rig from Bahrain to the Baltic and into the Caspian via the canal system. The work was for LukOil and the Astra is slated to drill at a location off the Russian coast.

Eerola stresses the importance of this type of business to Aker Rauma. "We have made considerable efforts over a long period to develop relationships with these yards. Our experience and the strong presence we have established means we are well placed for construction projects of all kinds in this important region."

As with the Spar business, Aker Rauma is nearing conclusion of its current series of Caspian contracts. However, it is bidding a range of work at various yards with which it has collaborated of late.


The Krassnye Barrikady yard is shown with the Astra drilling rig, which is currently being upgraded.
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SPIRAL BEVEL GEARS

Deepwater drilling needs driven by larger spiral bevel gears
ATA Gears in Tampere has been making gears for over 60 years. Investment in new gear cutting technology has now enabled the company to develop the capability to manufacture large diameter spiral bevel gears - previously only available up to 1.2 meters in diameter - to 2.0 meters or above. According to ATA there are only a few companies in the world able to make gears this size, especially for the marine and offshore sector where the company is the largest supplier.

A new AMK 1604 gear cutting machine marks the completion of a major phase in the biggest program of investment undertaken by ATA Gears. Larger production facilities and a new internal layout has also increased efficiency and helped the company to streamline production. The AMK 1604 machine is equipped with a testing unit which can be used not only for contact pattern testing but also for single flank rolling testing with advanced analysis software.

DP demands

The calls for large diameter gears are a consequence of the growing demand for dynamically positioned production platforms capable of operating in deep waters. By increasing the size of the gears from 47 in. to 80 in., the number of gears required for DP has in turn been reduced. Typically, ATA will supply four gears for a deepwater platform, with a delivery time of 12-14 weeks from one of the company's four factories based in the Tampere region of southern Finland.

ATA Gears supplies its gears to propulsion system suppliers for the offshore market and works in close cooperation with its customers to provide custom-made solutions for all its spiral bevel gears and gear boxes. "All the engineering calculations and technical analysis are now done by computer," says marketing manager Jaakko Barsk. "By working closely with the propulsion system companies, we become involved in the design process at a very early stage in a project."

The requirement for larger dimensions led ATA to work towards raising the net capacity of machines by decreasing the total weight wherever possible. "In the offshore sector where torque, weight, and space must all be optimized with great accuracy, custom-made gear units are more advantageous because we are able to supply fewer gears with greater capacities", says Barsk.

ATA's 80-in. diameter spiral bevel gear - launched last year - came into full production early 1999. "The market acceptance for the new gear is very good with almost all our current order book destined for offshore use," says technical manager Pente Hallila. "We have already supplied around 20 gears with diameters in excess of 1.2 meters and this fall we will deliver the world's largest spiral bevel gear with a diameter of 2.3 meters for a stone crusher."

Propulsion, thruster units aid multi-purpose vessel maneuvers

Thrusters and winches from Kamewa Finland figure prominently in several new drillships, rockdumpers, seismic and advanced multi-purpose vessels.

One of the Rauma-based company's latest deliveries was to the Olympic Princess, built at the Barttvaag Skipsvert yard near Alesund in Norway. This vessel is designed for duties ranging from pipe and light cable laying to platform supply and ROV support. To assist maneuvers in rough seas and currents, it has been equipped with two 2,200 kW Contaz 15 propulsion units with contra-rotating propellers, an Aquamaster UL 1201 retractable thruster and a Kamewa TT 2200 tunnel thruster.

Following a performance review of a sister ship, Brattvaag, Kamewa and the vessel designer decided to move the tunnel thruster forward on the Olympic Princess and position the retractable thruster behind it. Brattvaags' Stig Remoey, quoted in Kamewa's recent house magazine, claims that "this reduced the length of the tunnel thruster from 7.8 meters to 3.5 meters, which significantly reduced vibrations in the hull. In addition, we increased the length of the blades to get fewer revolutions and more power."

Sea trials were successful, Remoey added, proving that the configurational change enhanced the vessel's stationkeeping capability. Theoretical tests indicate that it can maintain station in winds of up to 60 knots. Also, the combination of the Contaz' units' efficiency, the diesel-electric machinery and the frequency converters has brought a 30-50% cut in fuel consumption, compared with other ROV vessels this size. Further more, sea trials revealed low noise levels. Measurements taken in the accommodation area were typically 44-54 decibels, compared with the 54-62 dB normally encountered on similar vessels.

Olympic Princess also is fitted with electrically driven Rauma winches from Kamewa Finland, a package which comprises two 10-ton anchor windlass units, three 8-ton mooring winches and two 10-ton tugger winches. The vessel is currently on an 180-day charter for ROV support duty, chiefly in the southern North Sea. It will then be chartered by ASCO for work as a supply vessel

Contaz 15 propulsion units have also been fitted to Simon Moekster Shipping's new platform supply vessel Stril Supplier, built at the YVC Ysselverf yard in The Netherlands. The twin propulsion units, each outputting 2,200 kW at 1,200 rpm, are supported by an Aquamaster UL 1201 thruster outputting 880 kW. In addition, the bow is equipped with an electrically driven Kamewa 2200 CP 880 kW tunnel thruster. Rauma Winches supplied two type MW 100E tugger winches, featuring a de-clutchable rope drum and fixed warping with nominal loads of 10 tons, two horizontal shaft type anchor windlass units, chain stoppers and three electrically driven MW 80 E mooring winches, also with de-clutchable rope drums.

Redundancy

Toisa Perseus is another multi-purpose vessel with two moonpools, fore and aft, designed for laying flexible pipes, well intervention, deepwater workovers, and subsea construction tasks. Onboard equipment includes two carousels with storage capacity for up to 1,250 tons of flexible pipe, plus two large work-class ROVs. The vessel, built a van der Giessen-de Noord in The Netherlands, has been taken on a five-year charter by Rockwater.

Dynamic positioning and redundancy were prime considerations in the design - a diesel-electric propulsion system was chosen based on four diesel engines each driving an alternator and providing combined installed power of 10,720 kW. In the stern are two low-set, US 3001 Aquamaster units with three Kamewa TT 2200 tunnel thrusters. Both Aquamaster units incorporate a stand-by hydraulic systems to insure continuous operation during servicing. The vessel includes dual redundant engine rooms and switchboard compartments.

Other recent installations by Kamewa Finland include:

  • Four UL 2001/6600 retractable thrusters for the Seahorse, a heavy loading vessel converted by Tideway subsidiary Deeprock for rock-dumping. This may already be working on North Sea pipelines - prior to setting sail, the thrusters were due to be retracted to reduce resistance and achieve optimum speed.
  • The seismic vessel Geco Angler, built by Flekkefjord Slipp and Makinenfabrik in Norway last year, features an electrically driven UL 2001/6100, 1,500 kW propulsion unit.
  • Deepwater Pathfinder, the new drillship built by Samsung in Korea for Conoco/ R&B Falcon, includes six UUS 6001 Aquamaster thrusters, each outputting 4,000 kW. They are fitted with patented 5° tilted nozzles which aid thrust by reducing propeller wash and hull interaction. Identical propulsion systems will be installed on two follow-up vessels.
  • Two Rauma winches were built for an AP Moeller anchorhandler, operating offshore Brazil.


The results of KMY's analysis shows enhanced transportation economy.
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LNG carrier improvements could be transferred to floating production units

Kvaerner Masa-Yards (KMY) has developed a series of simple, low-risk improvements to ensure the success of future liquified natural gas (LNG) projects by enhancing the transportation productivity of LNG carriers. The developments, which are a direct result of market pressure for cost reductions in the LNG chain, can be implemented individually, but KMY believes that, by adopting all its recommendations, the greatest benefit is in transportation economy which can be increased by 20-24%, together with an increased delivery capacity of 6-8% depending on the length of the route.

According to KMY, one of the simplest solutions for increasing capacity is to increase the volume of the LNG tanks by stretching the spherical tank shape upwards at the equator by adding a cylindrical extension.

In current LNG carriers, the equator ring is cylindrical in form and therefore the tank is not exactly spherical. The volume of tanks can be expanded by adding to the height of this cylinder within certain limits and thus increasing the volume of cargo. KMY has already designed such tanks in detail and obtained LR class approval for its design. The potential increase in earnings using this simple technique is considerable, due to the low cost of implementing this innovation.

Other factors that KMY has considered to increase the efficiency of LNG carriers is to reduce the boil-off rate and increase onboard re-liquefaction. Different propulsion and power plant options have also been weighed up in order to increase the overall transportation economy.

As a result, KMY has come up with a new-generation LNG carrier, based on a conventional Moss-type carrier, with the emphasis on the vessel's role as a cargo ship delivering cargo efficiently. In the new design, all four cargo tanks have been modified for larger volumes and tank insulation performance has been improved to reduce natural boil-off. Onboard machinery has been designed for heavy fuel oil only and a re-liquefaction plant has therefore been fitted with a thermal oxidizer as a backup unit. The propulsion power comes from a diesel-electric plant which supplies all electrical consumers including the reliquefaction plant and twin 13.6 MW Azipod drives.

The new design also has the superstructure and accommodation forward of the LNG tanks allowing reduced air draft and improved navigational safety. This arrangement also allows the under-deck spaces in the fore of the ship to be better utilized.

KMY has analyzed the efficiency of this design, compared to a conventional steam turbine Moss-type carrier, basing the analysis on one shipowner's methodology of calculating its LNG transportation costs. The effect of delivering more LNG, since it is adding value rather than saving costs, was valued at the same minimum cost that applied to a conventional vessel delivering one unit of cargo.

The comparison analysis showed that in addition to the huge improvement in transportation economy, in the range of 20-24%, the capacity to deliver LNG increased by 6-8%, depending on the length of the route. The varying percentage points shown in the summary curve (Figure 1), are largely due to reduced port costs and bigger cargo capacity on short routes and the effect of reliquefaction on long routes.

According to KMY, the natural progression from this new LNG carrier will be to combine LNG transportation with production facilities. Kvaerner Maritime is already in discussions with energy companies about this concept and the aim is to create low-cost solutions based on existing floating production technology. Although the concept is at an early stage, feasibility studies have shown that while the technology is basically the same, the main difference is dealing with high pressure gas. Current work is focused on checking design models throughout the process.;

Converted trawler contracted for 3-D program in UK North Sea

Aker Geo, the recently formed geophysics/ geoscience division of Aker Maritime, has been contracted to acquire 3-D seismic in the UK sector by Saga and Phillips Petroleum. Work will be performed by the first vessel in Aker Geo's fleet, nearing completion currently at Aker Finnyards in Rauma.

This latest order maintains the yard's track record of diversification over recent years. Following delivery of the multipurpose icebreakers/ pipelayers Nordica and Fennica in 1993 (the latter, now owned by DSND, has been performing record-breaking deepwater rigid line installations this year on Petrobras' Roncador field), the yard's offshore workload tailed off. However, it has flourished again following its purchase by the Aker group. Deliveries over the past two years include:

  • Botnica, the multipurpose light well intervention/icebreaker vessel
  • The deck structure for the West Navion I drillship
  • Aluminum structures for the Snorre B living quarters (still under construction).

Work on the new 3-D vessel - the Aker Amadeus - began in Rauma last October. This FIM300 million conversion order involves lengthening and widening of a Romanian-built trawler hull by 18 meters and 4.5 meters respectively to a new length of 84 meters and a breadth of 18.5 meters. Lengthening has been achieved by splitting the vessel amidships and installing a new 18-meter mid-section.

To widen the seismic equipment area and improve stability, two 2.25-meter wide sponsons have been fitted to either side of the ship for approximately two-thirds of its length. The vessel's draught will be around 6.1 meters.

For its new role, accommodation has been provided for 50 personnel, located in the main superstructure at the vessel's fore, with the engine room and diesel electric propulsion system amidships and the helideck/ seismic work areas aft. To accommodate this number of personnel and the instrument control room, a further deck has been added to the superstructure, below the existing bridge deck.

Two new decks have been installed at the rear end, with the one on top housing equipment for the eight-streamer spread. The helideck can accommodate a Super Puma-size aircraft. Below decks conversion work involved re-arranging the engine room and propulsion equipment layout (the latter generating total output of 12,000 kW). Three diesel generators, in the new mid-body section, each comprise a single nine-cylinder Wartsila L32 medium speed diesel engine driving a three-phase alternator. In transit, the vessel can attain a speed up to 14 knots. The former engine room now houses three off skid-mounted, electronically powered compressors, hydraulic power packs and other seismic-related systems.

Aker Geo's award was a letter of intent issued this April, to acquire 1,350 sq km of 3-D data in licences PL 1018 and 1019, granted to Saga and Philips in the UK's 18th licensing round. In addition to this type of work, Aker Amadeus will also be equipped for hydrographic research.

Aker Finnyards' other current offshore contract involves fabricating three 12 meter by 20 meter by 7 meter aluminum sections, weighing 120 tons, for the Snorre B living quarters, under construction at Leirvik Sveis in Norway. The Snorre B semisubmersible's hull is being built by Dragados in Cadiz. Aker Finnyards' knowledge base for this project derives from its experience in 1993-96, when it constructed the world's three largest aluminum ferries.

The Rauma yard is 260 meters long with an 85-meter wide drydock. Lifting capacity is 300 tons, with a 600 ton transport capacity. The graving dock can accommodate vessels up to 150,000 dwt.

Valve monitoring via the Internet

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FINNISH COMPANY PROFILES


Aker Rauma Offshore
Aker Rauma Offshore(ARO) specializes in offshore construction projects worldwide, using the most advantageous construction sites and subcontractors to maximize cost-efficiency. Products and services include turn-key offshore contracts, engineering and construction contracts, contract management, engineering and feasibility studies and procurement and logistic services. These are offered for SPAR platforms, offshore exploration rigs, floating and jack-up production platforms.

ATA Gears
ATA Gears is a major supplier of spiral bevel gears and custom-made gear units for marine applications all over the world. With over 60 years of experience and modern engineering and production technology, all gears and gear units are made to meet customers' specific needs. The company offers spiral bevel gears up to 2,000 mm (80 in.), finishing options from lapping to grinding and a wide selection of materials.

KaMeWa Finland
Extreme reliability is vital in all offshore operations. In this respect, the list of KaMeWa's references includes a large number of drilling and production vessels, supply and AHT vessels as well as crew vessels on which the company's propulsion and winch systems are used, both for the accurate positioning and assisting of the vessel.

Larox Flowsys
Larox pinch valves have been engineered for abrasive and aggressive on/off and control slurry applications. The valves are used widely in bulk and mud handling, drilling mud, cementing template units, cement and bulk carriers, produced water, cyclones and hydrocyclones, underwater sandblasting, fire water isolation, sea water, sanitary service and sewage treatment.

Kvaerner Masa-Yards
Kvaerner Masa-Yards builds gas carriers, floating production and storage units, icebreakers, ice-going tonnage and other special ships for the oil and gas industry. The company operates two newbuilding yards and a factory for prefabricated cabin modules. The Arctic Technology Centre (MARC) handles Arctic research and development work. Recent offshore sector deliveries are Njord B, an FSU for Norsk Hydro Produksjon, an FPSO hull for Kvaerner Oil & Gas/Esso Norway and two icebreaking.

Marioff
Marioff provides high integrity water mist fire protection systems for the offshore industry worldwide. Recent projects include HI-FOG systems for major oil and gas companies for protection of turbines and other special hazard machinery spaces as part of a halon replacement program.

Rautaruukki
Rautaruukki Steel Plate Products handles the manufacture and sales of hot-rolled plate products, prefabricated plate products, and plate components. The hot-rolled steel products and prefabricated plate products of the company are recognized as quality materials for offshore and marine technology projects, steel construction, and engineering purposes. For the special purposes of marine technology the company supplies icebreaker steels and thermomechanically rolled offshore steels.

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