New Concept Design of Large FPSO for Santos Basin - Brazil

Abstract

The offshore oil fields exploitation, especially giant fields in the Santos basin, brings with it demands for systems capable of operating at ultra-deep waters, with high capacity production wells and high gas/oil ratio (GOR) with large amount of contaminants. In this scenario, steel catenary risers (SCRs) offer the simplest, most robust and lowest cost solution. However, due to its rigidity compared to flexible risers, this solution is affected by the high dynamic forces imposed on the top of the riser, in consequence of the FPSOs large vertical movement in waves, making difficulties on their application in conventional FPSO hull units. This dynamic problem is caused by environmental conditions of the region, which are harsher than those observed in the Campos Basin. The reservoir characteristics described above demands high-capacity oil & gas process plants, larger than those used today in the Brazilian offshore. Initial estimates show that these plants require a much larger deck area than conventional platforms and, more than that, a greatest breadth of the vessel. This paper presents the ULFPSO (Ultra Large Floating Production, Storage and Offloading) concept, developed to satisfy such conflicting requirements. The design process, including the preliminary sizing, physical scale model test and the hull form optimization are discussed and presented in this paper based on a high-capacity process plant case study.