Roncador P-52 Hybrid Riser Review: Key Concepts, Construction and Installation Challenges

Abstract

Abstract The first Petrobras Hybrid Riser was installed in Campos Basin and is part of the Roncador P-52 oil export system. This system, which connects the SS platform P-52 (1800m water depth) to the fixed unit PRA-1 (100m water depth), is in operation since November 2007 comprises an 18 in diameter flowline and the Free Standing Hybrid Riser (FSHR). The FSHR is composed by a grouted foundation, 1500m of rigid steel riser, a near surface Buoyancy Can and a flexible jumper connecting the top of rigid riser to the platform. The basic design evolved almost until installation, in October 2007, due to engineering, construction and supplier restrictions. Key concepts of design and main considerations that led to this Hybrid Riser final design are reviewed. Moreover, this paper presents some of the aspects of construction and installation that influenced the implementation and some of the lessons learned are discussed. The Riser foundation and flexible jumper were free issued by Petrobras to Contractor and some of the interfaces over the design are addressed as well. This paper points out some of the key issues to be taken into consideration to improve the design of future projects and presents some important lessons learned that can be used for further studies in ultra deepwater large diameter Hybrid Risers. Introduction In November 2007 the first Petrobras' Hybrid Riser, part of P-52's oil export system - also known as PDET Profundo A project, started operating in Roncador field in Campos Basin, Brazil. The system has been operating successfully over the past years proving the efficiency of the concept. This riser concept allows for a more compact subsea arrangement compared to Steel Catenary Riser (SCR) as it was the case of P-52' FSHR which was installed nearly 300m from the platform. Some other advantages were also pointed out in Sertã et al (2001) and include:Loads: FPU motions are transferred to the Flexible Jumper and not to the main catenary (in case of SCR).Reduced Loads on the FPU: the loads come uniquely from the weight of the catenary flexible jumper and are shared between the buoyancy can and the FPU. Installation with Pipelay Vessel: The installation can be done by standard pipelay vessels with standard laying methods (J-Lay, Reel-Lay or S-Lay) depending on the specific design restrictions which, in this case, were suitable only to J-Lay method. Improved Installation Schedule: It does not depend on the FPU schedule. The installation campaign can start with much anticipation to the platform's arrival. Suitable for Ultra Deepwater: In certain situations like water depths beyond 2000m it may be impractical to have a flexible riser (or bundle). This was the case with P-52 where the concept was installed in depths of 1800m.