Auger Shell Sets Record With Gulf Of Mexico Tension Leg Platform
Late last year, following four years of construction, Shell 011 Company's recordsetting "Auger" tension leg platform (TLP) was towed out to its new home, some 255 miles southeast of Houston, Texas, in the deep water Gulf of Mexico. Installed in 2,860 feet (871.7 m) of water, the Auger TLP reportedly set a world water-depth record for a drilling and production platform, and surpassed the existing Gulf of Mexico record by more than 1,000 feet (304.8 m). "It (Auger) opens a new chapter in industry's efforts to tap the tremendous potential of this deep water frontier," said Jack E. Little, Shell's executive vice president of Exploration and Production.
At the installation site, 12 tendons made of steel pipe, each more than half a mile long, attach to the corners of the floating platform and anchor to footings on the sea floor. The entire Auger project will cost approximately $1.2 billion. Production, which at press time was just about to begin, is expected to reach a peak daily rate of46,000 barrels of oil and 125 million cubic feet of gas in the year 2001. Total recovery from the Auger field is estimated at 220 million barrels of oil and gas equivalent. Auger's deck was built by McDermott Inc. in Morgan City, La., and the hull was built by Belleli S.p.A. in Taranto, Italy. The deck and hull were connected at sea last October, and from there the structure was towed for its final hook up. The deck section measures 290 feet (88.4 m) by 330 feet (100.5 m). Shell also announced plans to build its second TLP to develop its Mars field in the Gulf of Mexico. The Mars TLP will be installed by 1996 in 2,933 feet (893.9 m) of water, surpassing Auger's water depth record. AUGER TLP SPECIFICS The Auger Prospect encompasses four OCS leases in the Garden Banks Area—blocks 426, 427, 470 and 471—located about 255 miles southeast of Houston and 214 miles southwest of New Orleans. The leases were acquired for $11.3 million, and are 100 percent owned by Shell Offshore Inc.
The discovery well was drilled on block 426 in 1987; one other well and three sidetracks were drilled on the four blocks and 3D seismic information was used prior to making the decision on development. Shell Offshore Inc. made public its decision to develop Auger in December, 1989. The Auger TLP is the first in the Gulf of Mexico to support both a drilling rig and complete production facilities. Of the total $1.2 billion project cost, about 65 percent was spent for fabrication and installation of the hull, deck, facilities, drilling rig and pipelines; with the remaining 35 percent going for drilling and completion of the wells.
• Construction & Fabrication: The Auger superstructure was designed and engineered by Shell Oil Company, and in total, more than 740 companies in 30 states and 33 companies in 11 countries were involved in the construction of the TLP. The steel weight of the TLP is 39,000 tons, and it is designed to withstand hurricaneforce waves of 71 feet (21.6 m) and winds of 140 mph. The hull, which weighs approximately 20,000 tons, is comprised of four circular steel columns, 74 feet (22.5 m) in diameter and 159 feet (48.5 m) high, and four rectangular steel pontoons, 35 feet (10.7 m) wide and 28 feet (8.5 m) high, which connect the bottoms of the four columns. The deck design is an open truss box steel girder, and weighs approximately 10,500 tons. • Tendons: Various components of the tendons were manufactured by Oil States Industries in Arlington, Texas; ABBVetco in Houston; and Hunting Oilfield Services in Aberdeen, Scotland. The tendon sections were assembled by Aker-Gulf Marine at Ingleside, Texas. There are 12 tendons, three per corner, each with a diameter of 26 inches and a wall thickness of 1.3 inches. Each tendon is approximately 2,760 feet (852.2 m) long, and the total weight for the 12 tendons is 5,800 tons.
• Foundation Fabrication: The foundations were fabricated by Aker- Gulf Marine, and installed on location by Herremac. There are four foundations, one per corner, consisting of templates held in place with piles. The piles are connected to the templates by means of Hydro- Lok connectors. The templates are steel truss frames, 60 feet (18.3 m) by 60 feet by 30 feet (9.2 m) high. There are four piles per template, each 72 inches (183 cm) in diameter and 427 feet (130.1 m) tall. The four templates weigh 2,440 tons, total; the piles weigh 3,250 tons, total.