Perdido Hub

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Located at Alaminos Canyon Block 857 approximately 220 miles (354 kilometers) from Galveston, Texas in the Gulf of Mexico, is Perdido, an oil and gas spar production facility. Shell, 35% shareholder and operator, along with BP, 27.5%, and Chevron, 37.5%, are developing the regional host facility.

Since the project began, multiple world records were made in the offshore industry. Perdido is the deepest oil development, the deepest drilling and production platform, and will produce from the deepest subsea well in the world.

The hub produces from three fields: Great White, Silvertip and Tobago. The fields are situated on the Perdido fold belt, offshore in the deep northwestern section of the Alaminos Canyon outer continental shelf area. The fold belt region is in water depths ranging from 7,546 to 9,843 feet (2,300 to 3,000 meters), which are considered some of the deepest waters in the gulf.

In order to develop the wells in ultra deep depths, and reduce costs, the companies decided to use a common processing hub, Perdido. The spar incorporates drilling and capabilities to gather, process and export production within a 30-mile (48-kilometer) radius.

Fields

Development drilling of the fields commenced in July 2007 and was performed by the Noble Clyde Boudreaux semisubmersible-drilling rig. Shell set a world record in December 2008 for the deepest completed offshore production well, at about 2,852 meters (9,356 feet) below the water’s surface. Even though the first of the three fields, Great White, was discovered in 2002, the companies agreed to move forward with development in 2007.

Great White

Great White is located on Alaminos Canyon Block 857 in a water depth of 8,000 feet (2,438 meters), and is owned and operated by Shell, 33.34%, while Chevron and BP each hold a 33.3% interest.

Discovered in May 2002 by the Deepwater Nautilus semisub, the discovery well was drilled to a true vertical depth of 19,907 feet (6,068 meters). Then in 2004, an appraisal well was drilled to a true vertical depth of 15,035 feet (4,586 meters). Shell drilled a total of five wells at Great White, spudding the fifth well in March 2004.

Silvertip

Silvertip is located in Alaminos Canyon Block 815 and is 60% owned by Chevron, while operator Shell owns the remaining 40% interest. The field was discovered in August 2004 in 9,200 feet of water (2,804 meters) and drilling reached a total depth of 14,778 feet (4,504 meters).

Tobago

Considered the world’s deepest subsea completion to date, Tobago is located in Alaminos Canyon Block 859 in 9,600 feet (2,926 meters) of water, which surpassed the previous record set by Silvertip. Shell, the operator, owns 32.5%, along with its co-owner Chevron, 57.5%, and Nexen, 10%. In 2004, the well was drilled to a total depth of 18,510 feet (5,642 meters), and then a sidetrack well was drilled to 18,425 feet (5,616 meters).

Subsea Development

Because the field’s water depths are greater than previously encountered anywhere in the world, and the need to drill multiple wells from several fields to reduce cost and environmental impact, the companies decided to use a 555-foot (169-meter) spar instead of a typical tension leg platform. The cylinder spar is a partially submerged offshore drilling and production platform that is particularly adapted to ultra-deepwater and fierce hurricane weather.

Once the facility was chosen and construction began, subsea development commenced.

Oceaneering International received a contract by Shell for the fabrication and installation of subsea hardware for the Perdido project. The hardware included 29 flowlines and well jumper spools, and a pipeline tie-in sled.

FMC Technologies performed the subsea completion and processing systems, which included 17-subsea trees, two subsea manifolds, five-subsea caisson separation and boosting systems, a topside and subsea controls, and related subsea equipment. Also included in the scope of work is the design of the steel catenary risers, top tension risers and umbilicals.

Acergy North won the transportation and installation contract for the subsea production umbilicals. The work scope included 37 miles (60 kilometers) of steel-tube super duplex subsea production umbilicals, four dynamic and three static, associated flying leads and subsea hardware.

Five risers hang down to the seafloor, and then branch out into clusters of connected wells. On the seafloor, 22 wells, extending more than 14,000 feet (4,267 meters) from the surface, will be linked to the Perdido spar, with an additional eight tie-backs from subsea completions. Fifteen hundred horsepower electric pumps will bring oil to the surface against extreme pressures from three undersea fields, while gas is separated on the sea floor and sent to the production unit.

Perdido Spar

The spar facility was installed in August 2008. The Perdido spar is a massive steel structure that is 568 feet (173 meters) tall, 112 feet (34 meters) in diameter and floats on a sunken cylinder. Perdido was constructed by Technip in Pori, Finland, and began its journey to Texas in May 2008. Kiewit is constructing the topsides in Ingleside, Texas.

Moored in 7,817 feet (2,383 meters) of water, nine chains and polyester rope mooring lines, roughly 2 miles (3 kilometers) in length, secure the 50,000-ton (45,359-tonne) spar. On this project, Heerema Marine Contractors installed the world’s deepest permanent mooring anchor pile in 8,631 feet (2,632 meters) of water using the deepwater crane vessel (DCV) Balder.

In 2006, Shell awarded Technip a contract to provide the Engineering Procurement and Construction (EPC) of the spar hull and mooring system. The contract covers the design and fabrication; load out onto a transportation vessel, and transportation and quayside delivery.

Production

The facility began production on March 31, 2010 from five wells on the Great White field, with all wells expecting to come online by 2016. The spar is designed to produce 100,000 bopd and 200 MMcf/d (6 MMcm/d).

The spar’s life expectancy is 25 years. Shell did not disclose the cost of the facility, but insiders are estimating costs to total $4 billion, given the size and complexity of the project.

Further Development

While development is on going in this area, Chevron and partners continue to evaluate development alternatives for other discoveries in the Great White-Perdido-Foldbelt area, which include Tiger and Trident.

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Posted on October 29, 2011, in Gulf of Mexico and tagged , , , , , , , , , . Bookmark the permalink. 3 Comments.

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