Atlantis Platform, Gulf of Mexico, USA

Considered one of BP's most technically challenging projects ever, the Atlantis platform is currently the deepest moored floating dual oil and gas production facility in the world and weighing in at 58,700t, it is also one of the largest. BP is operator of Atlantis with 56% ownership with its partner in the venture, BHP Billiton, having a 44% working interest.

The platform is located 190 miles south of New Orleans in 7,070ft (2,150m) of water, the field itself occupying five blocks – Green Canyon 699, 700, 742, 743 and 744 – with water depths ranging between 4,400ft and 7,100ft (1,338m and 2,158m).

Originally scheduled to start in 2006, the hurricane of the 2005 season delayed progress and hiked prices, Atlantis finally produced its first oil in October 2007, with full commissioning – and a ramp up in production – following in mid-December.

Initially producing at a daily rate of around 10,000 barrels of oil, Atlantis has a production capacity of 200,000 barrels of oil and 180 million cubic feet of gas a day, with the expectation that it will have reached plateau production by the end of 2008.

The field has an estimated life of 15 years and oil reserves of 635,000 million barrels of oil equivalent.

ATLANTIS PRODUCTION AND DEVELOPMENT

The Atlantis platform employs an integrated semi-submersible design, with the Production Quarters (PQ) platform supported by a separate dedicated Mobile Offshore Drilling Unit (MODU).

In addition to the semi-submersible platform, field development uses a network of wet-tree subsea wells – with the potential for more than 18 to be tied back to Atlantis – while development drilling and well completion involved Global Santa Fe's submersible rig, Development Driller II, a Long-Term Development Unit (LTDU).

Transporting the oil and gas to existing shelf and onshore interconnections uses the Caesar and Cleopatra pipelines, respectively, which form part of the largest-capacity deep-water line ever built – the Mardi Gras transportation system – which is 65% BP-owned. BHP Billiton has a 25% equity share in the component Caesar pipeline and a 22% stake in Cleopatra.

Crude from Atlantis is transported to the Ship Shoal 332B platform, from where subsequently the multiple pipeline connections allow it to reach the major US markets and interconnections. Natural gas is channelled along Cleopatra to the Ship Shoal 332A platform, where it interconnects with the Manta Ray gathering system, before being transported to Louisiana along the Nautilus gas transportation system.

TOPSIDES AND HULL

The hull was built in Okpo, South Korea and the topsides modules were fabricated by Ray McDermott in Morgan City, Louisiana, their subsequent integration taking place at Ingleside, Texas.

The topsides layout consists of three production / utilities modules, amounting to a lift weight of 14,125t. Duffy & McGovern supplied the accommodation, including sleeping and office modules, laundry facilities, recreation areas and galleys together with associated sewage and fresh water tanks. The finished installation has a main power generation capability of 63MW.

With a main deck of 403ft x 294ft, the hull has a displacement of 88,826t, a normal draft of 85ft and four columns of 67ft x 67ft in height; mooring is achieved via a hydraulic linear chain jack mooring system using 12in x 5.75in wire rope and chain with suction pile. Permanent mooring piles were installed at a depth of 2,134m by Heerema Marine – a record in 2005, which they subsequently went on to break by 308m as part of the Independence Hub project.

The production quarters were moored at their permanent location in August 2006.

THE FUTURE OF ATLANTIS

Atlantis is one of a series of important deepwater projects that BP and BHP are undertaking, both jointly and separately – and is widely expected to make a significant difference to the fortunes of both companies.

The petroleum division of BHP – once the biggest revenue earner – has been described as 'relatively flat' over recent years.

With the contribution of other fields in the Gulf, including Neptune and Genghis Khan where BHP is the operator, having a 35% and 44% share in each, respectively, their regional production is set to rocket from a 2007 total of 12,000bpd to 100,000bpd.

BHP's pre-tax petroleum earnings from the Americas are predicted to hit $2bn in 2009 – and at least half of this is expected to be coming from Atlantis. According to Brendan Harris, senior analyst at Macquarie Equities, Atlantis could represent as much as 5% of BHP's anticipated $24.8bn pre-tax profit for the year.

BP has a long record of major deepwater developments in the Gulf of Mexico, where oil production has increased from around 2.3% of US oil production (151,000bpd) in 1995 to nearer 18% (936,000 barrels) today. BP's planned start-up of the long-delayed Thunder Horse platform towards the end of 2008 – some three years behind schedule – will boost this still further.

It will be the largest offshore platform in the world – with a capacity to produce 250,000bpd and 200 million cubic feet of gas a day – and when combined with Atlantis, add around 6.5% to total US production.

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