Subsurface Buoy Configuration for Rigid Risers in Ultra Deepwater

The Exploration and Production Department of Petrobras asked the R&D Center the development of a production system for 1800 m water depth, in Campos Basin, which would allow the installation of Steel Caterany Risers (SCR) in the starboard side of a production platform. The subsurface buoy concept was chosen as one of the alternatives. This concept has being developed since the preliminary studies conducted in the first phase of JIP Deepstar. This concept has an advantage of uncoupling the movements of the platform from the risers, reducing the loads due to the risers in the platform and allowing the installation of this system before the installation of the production vessel, anticipating the production of the field. This article shows the main characteristics of the buoy, its sizes, results of structural analyses and installation procedures for a buoy which sustains 14 SCR and 5 umbilicals in one side and 14 flexible jumpers and the same 5 umblicals in the opposite side. This concept was tested in two model test tanks, where it was verified that this concept is feasible. Also, information related to a field trial with a prototype installed in Brazilian waters will be presented.