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Brutus Tension Leg Platform
Brutus encompasses two OCS leases in the Green Canyon area - Blocks 158 and 202. It is located approximately 165 miles southwest of New Orleans in water depths ranging from 2,750 to 3,300 feet.
The leases were acquired in OCS Lease Sale 98 in March 1985. Shell Deepwater Development Inc. owns 100% of the leases.
The discovery well was drilled on Green Canyon Block 158 in December 1988. An appraisal well was drilled on Green Canyon Block 158 in 1994. A third well was drilled in 1997 on that same block, with a bottom hole location on Green Canyon Block 202. Target reserves are in the Plio-Pleistocene sands at a depth of approximately 12,500 - 17,500 feet, subsea.
Development Plans
Shell announced in April 1999 its plans to develop Brutus utilizing a tension leg platform (TLP) to be installed on Green Canyon Block 158 in 2,985 feet of water.
Batch setting of the eight wells was completed January 3, 2000, using Diamond’s Ocean Worker semisubmersible drilling rig. Six of the planned development wells for the eight-slot TLP were subsequently predrilled to total depth following the batch set operations. Drilling operations using the Diamond Worker rig concluded in April 2001.
An H&P contract platform rig completed all six pre-drilled wells and drilled and completed the two remaining wells.
Installation of the TLP took place in June 2001. Heerema was the contractor for the installation using the derrick barge, Hermod.
Oil production from the platform is transported approximately 26 miles via a 20-inch diameter pipeline to South Timbalier 301 “B” platform where it will be connected to the existing Amberjack System.
Gas production from the platform is transported approximately 24 miles via a 20-inch gas pipeline and will be connected to the existing Manta Ray Offshore Gathering System in Ship Shoal Block 332.
Production
Production began August 2001.
TLP Engineering/Construction Details
Hull
The hull is comprised of four circular steel columns, 66.5 feet in diameter and 166 feet high. Pontoons connect the columns which are 35.5 feet wide and 23 feet high with a rectangular cross section.
Built by Daewoo Heavy Industries Co. of South Korea, the hull weighs approximately 13,500 tons, with a total displacement of 54,700 tons. On December 7, 2000, the hull left Daewoo's Okpo fabrication yard, transported by Dockwise's Mighty Servant 3 and arrived at CSO Gulf Maritime's integration facilities near Ingleside, TX, on January 30, 2001.
Deck
The installed deck has dimensions at the outside truss rows of 245 feet square and approximately 40 feet high. It is composed of five modules: process, drilling, power, quarters, and wellbay, and the deck modules are open truss frame design with a total structural steel weight of approximately 7,650 tons. The total topside weight is approximately 22,000 tons, including all process equipment and the drilling rig.
J. Ray McDermott built the modules at its Amelia, LA, fabrication yard. The modules arrived at CSO Gulf Maritime's integration yard in January and February 2001.
Integration
The hull and deck were integrated at CSO Gulf Marine’s Ingleside fabrication yard near Corpus Christi, TX. The five deck modules were lifted into position on the hull using the specialized lifting device originally developed for the Mars TLP integration.
Tendons
There are 12 tendons, 3 per corner, each with a diameter of 32 inches and a wall thickness of 1.25 inches. Each tendon is approximately 2,900 feet long. The total weight for the 12 tendons is approximately 7,500 tons. The TLP foundation system is comprised of 12 piles, to which the tendons are attached. The piles are 82 inches in diameter and 340 feet long, weighing approximately 245 tons each. Aker Gulf Marine fabricated the piles and tendons at their Ingleside fabrication yard near Corpus Christi, TX.
Drilling and Production Topsides
There are 8 well slots, with the well layout on the seafloor arranged in a rectangular pattern. The TLP supports a contract drilling rig, equipped with a surface BOP and high pressure drilling riser. There are complete separation, dehydration and treatment facilities designed to process 110,000 barrels of oil and condensate per day, plus 150 million cubic feet of gas per day and 30,000 barrels of produced water per day. The quarters module houses up to 94 people, and contains a control room and an emergency response center.
Pipelines
A 20-inch diameter oil pipeline and 20-inch diameter natural gas pipeline transports production. Installation of the steel catenary risers occurred immediately after TLP installation. J. Ray McDermott, Inc. installed the oil and gas pipelines beginning in the second quarter 2000 using the dynamically-positioned Derrick Barge 16.