Matterhorn Field, Gulf of Mexico, USA

The Matterhorn field is located in Mississippi Canyon Block 243 in the deepwater Gulf of Mexico, approx. 170km southeast of New Orleans. It lies in 850m of water.

The development plan calls for the field to come onstream in the second half of 2003 and to reach a production rate of 40,000 barrels of oil equivalent per day by the end of the year.

The Matterhrorn field is wholly owned and operated by TotalFinaElf E&P USA. After examining a number of development options, the designers settled on the use of a mini tension leg platform. The company opted for an Atlantia SeaStar design of the type previously installed on such deepwater projects as Chevron's Typhoon and British-Borneo's (Agip) Morpeth and Allegheny fields. Because of the field however, a larger version than the existing designs was deemed necessary.

The Matterhorn platform, at 4,500t, will stand as the biggest of its type - double the size of the previous units and the first unit of this design to incorporate supporting vertical access production flowlines running through the central moonpool and controlled by surface (dry) trees. The contract for the hull was won by Keppel Fels in Singapore, making Matterhorn also the first one built outside of the Gulf of Mexico.

MATTERHORN SEASTAR HULL

The fabrication of the Matterhorn SeaStar hull structure began on 28 January 2002 and was completed by the end of the year. The construction is based on a relatively large central main column with a diameter of 84ft. It has a design draft of 104ft.

At the base of the column are three pontoons which project out to give the structure an effective radius of 179ft. At the point where they are attached to the main column the pontoon heights are 42 ft, however these taper down to just 27ft at the tip.

This hull structure is designed to support a payload 16,850kips (thousand pounds). The hull itself will weigh approximately 12,280kips, of which the primary hull structure will account for 10,420kips. Altogether, the platform will have a displacement of 52,800kips.

In early 2003, the structure was sailed out of Keppel Fels yard across to Pascaguola, Mississippi, to await mating with the topsides.

MATTERHORN TOPSIDES

The Matterhorn topsides design is distributed over three decks. This deck arrangement was constructed at the Gulf Marine Fabricators in Ingleside, Texas. Paragon Engineering was responsible for the design of the topside facilities, employing the 3D PDMS (Plant Design Management System). The company expended over 60,000 man-hours on the design.

The deck free board is designated at 69ft and the decks will have an area of 140ft². The operating weight of the decks and facilities will be 13,350kips.

In order to process the Matterhorn hydrocarbons the platform design will have process capacities of 35,000b/d of oil, 55 million scf/d of gas, 20,000b/d of water treated and 30,000b/d of water injected.

The wellbay design is centred on nine well slots although it is envisaged that initial production will use only eight of the available spaces. Located at the top of the platform will be a 1,000hp drilling rig which will also be give the field engineers the capacity to add future tiebacks.

The design will also include quarters for 22 men.

The Matterhorn TLP will be connected to the seabed by six 32in tendons. These have been fabricated by Kiewit Offshore Service, also in Ingleside. Each of these tendons will be secured by means of an independent, 96in-diameter, 415ft pile at the seabed.

The offshore installation will be carried out by Heerema's Balder crane vessel.

Click here for printable version