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January 2012 www.sname.org/sname/mt to work in harsher and more challenging regions of the world, and, until recently, was the workhorse of the international o shore drilling industry. A life-sized exhibition of o - shore platform technology is on display at the O shore Energy Center?s Ocean Star water- front museum in Galveston, Texas. Semisubmersible production platforms were rst deployed in the North Sea in 1975 (Hamilton Bros. Argyll), in Brazil in 1977 (P-07), and the Gulf of Mexico in 1987 (Placid?s Green Canyon 29), as noted in Figure 1. ese early platforms were all based on converted drilling units, and had modest payload and produc- tion capacity. e principal advantages were a ready source of candidate rigs, shortened development schedule, low capital expendi- ture, and exibility for future redeployment. Gradually the FPU solution was adapted for larger platforms, deeper water, and harsher environments, with more converted platforms and eventually new purpose-built semisub- mersible production platforms in the North Sea, Brazil, and the Gulf of Mexico. Placid Oil chose to develop the GC 29 block in the Gulf of Mexico using a oating production system based on one of its exist- ing semisubmersibles, the Penrod 72. e rig was extensively modi ed to increase its pay- load capacity and stability, add production equipment, and upgrade its mooring system. e Placid system was very innovative at the time, with a free-standing hybrid production riser system that could be disconnected from the platform in a hurricane. The platform was installed in 1987 and was a technical success?but probably not a commercial suc- cess, because the reservoir underperformed. In 1992, Enserch commissioned the engineering and conversion of an Ocean Victory-class rig to become the Garden Banks (GB) 388 platform, located in 2,130 ft. (650 m) water depth in the Gulf of Mexico. is unit had extensive modification of its hull and deck, adding stability sponsons, deepwater mooring equipment, and process equipment for this site. e GB 388 system was designed to re-use the free-standing hybrid production riser system developed for the GC-29 project. e GB 388 unit was successfully deployed in 1995, and later decommissioned in 1999. Maturing the concepts Floating production units gained stature and acceptance with operators in the 1980s and ?90s. A succession of newbuild oating produc- tion semisubmersibles followed in the North Sea, including Balmoral (1986), Troll C (1998), Asgard B (2000), and Kristin (2005). Visund (1999) was another drilling and production unit. All of these units were purpose built for harsh environments?water depths ranging up to 1,100 ft. (335 m) and oil production rates up to 190,000 barrels of oil per day (BOPD)?proving that semisubmersibles were an e ective solu- tion where large payload capacity and low motions were required. Similar developments occurred with Brazil?s gradual extension into deeper water. Petrobras deployed newbuild oating production semisubmersibles, includ- ing P-13 and P-14 (newbuilds based on a TH-2800 design), as well as P-51, P-52, P-55, and P-56 (purpose-designed newbuilds), capable of production of around 180,000 BOPD in water depths ranging up to 5,900 ft. (1,800 m). ese units were partially or completely constructed in Brazil, which also was the site of the application of the rst synthetic taut-leg mooring system (on P-26), marking a signi cant breakthrough in increased water depth capability due to the much lighter weight mooring system. e Gulf of Mexico development activity extended to 5,000 ft. water by the late 1990?s, but the pipeline infrastructure lagged behind the discoveries. Activity picked up in 2000 with the discovery of large oil deposits in the deepwater Miocene trend and started the development of deepwater gathering systems. Large discoveries in water depths up to 10,000 ft. (3,050 m), and developments that followed, employed a variety of systems, including TLPs, spars, and semisubmersibles, with the Independence Hub at 7,920 ft. (2,414 m), giv- ing it the current Gulf of Mexico depth record. Several large purpose-built semisubmers- ible FPUs were developed in the early 2000?s, 1970s 1980s 1990s 2000s 2010s 1975 First oating production semi Argyll FPS- N Sea 1997 First classic spar Neptune Spar 1984 First TLP Hutton TLP N Sea 1989 First TLP in Gulf of Mexico Jolliet TLWP 1983 First FPS in Brazil P FPS 1987 First semi FPS in Gulf of Mexico Na Kika 2005 Biggest semi Thunder Horse FPS2010 Deepest spar Perdido spar 2002 First truss spar Nansen Spar 2014 Deepest TLP Big Foot TLP2011 First FPSO in Gulf of Mexico Cascade & Chinook 2014 Largest semi (displacement) Jack & St Malo FPSCOURTESY BOEMRE FIGURE 1. EVOLUTION OF DRILLING AND PRODUCTION PLATFORMS 32_37_Praughtfeature_SNAME_Jan12_P3.indd 3412/22/11 3:39 PM