Introducing Single Deck Topside Concept for Large New-Build FPSOs in West Africa

Abstract The era of the low oil price makes all key players to establish the distinct business and technical strategies from the past successful models of offshore plant for better construction and operation. This paper describes design features of a single deck topside and wide beam hull concept for large new-build FPSOs in West Africa. The single deck topside is a common concept in the platform of small production capacity, while it is not applied to large new-build FPSOs. Generally, multiple deck topside has been introduced to large FPSOs to carry a lot more equipment within allowed footprint area. But, it has caused heavy structural reinforcement and complicated layout in topside. To overcome this shortcoming in Large FPSOs, our approach increases the hull deck area, mainly by the breadth more than conventional vessel. Equipment is grouped by the functional similarities and arranged on larger main deck. Other fitting and less heavy equipment may be located on the self-supporting structure. The major piping route, valve location and topside structure are also verified. Combination with mega-block modules could enhance the benefits of this concept, especially in saving the execution time and obtaining the design flexibility. Further, it creates more value of the maintainability by open overhead access to the main equipment, not compromising the safety. Initial hull sizing is carried out in terms of optimizing weight and motion characteristics. Several barriers are reviewed for realizing the single deck topside and wide beam hull, based on the previous experience. Finally, the benefit of this concept is validated by the 3D modeling. In this paper, the main findings and further discussion points from the study are addressed.