Atlantis Deepwater Oil and Gas Platform, Gulf of Mexico, United States of America

Atlantis oil and gas platform

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

"The Atlantis platform is the deepest moored floating dual oil and gas production facility in the world."

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 reached plateau production by the end of 2008. It has a production capacity of 200,000 barrels of oil and 180 million cubic feet of gas a day.

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

Atlantis deepwater platform production and development

The Atlantis platform employs an integrated semi-submersible design, with the production quarters platform supported by a separate dedicated mobile offshore drilling unit.

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.

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 deepwater 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."

Crude from Atlantis is transported to the Ship Shoal 332B platform, from where the multiple pipeline connections allow it to reach 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.

In October 2011, EMAS AMC was contracted to install and replace subsea systems including manifolds, pipeline end manifolds, jumpers and associated the Atlantis field.

Topsides and hull

The hull was built in Okpo, South Korea, and the topsides modules were fabricated by Ray McDermott in Morgan City, Louisiana, US, and their subsequent integration took 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, 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.

Future of Atlantis

Atlantis is one of a series of important deepwater projects that BP and BHP are undertaking, 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.

"Atlantis is one of a series of important deepwater projects that BP and BHP are undertaking."

With the contribution of other fields in the Gulf, 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.

BP has a long record of major deepwater developments in the Gulf of Mexico. The start-up of the BP's long-delayed Thunder Horse platform in 2008 - some three years behind schedule - promoted this still further.

It is 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.