The Roncador P-52 Oil Export System - Hybrid Riser at a 1800m Water Depth

摘要

The PDET (Oil Flow Master Plan) project consists of the P-52 oil export system, an 18in oil export pipeline and a Free Standing Hybrid Riser (FSHR) connecting the P-52 floating production unit to the fixed platform PRA-1, both located in the Campos Basin, offshore Brazil. The base case for the export system comprises a vertical riser and an export pipeline. The FSHR consists of a vertical steel pipe tensioned by a near surface Buoyancy Can with a flexible jumper connecting the top of the riser and the FPU. The foundation is a drilled and grouted pile. The oil export pipeline is 56km long, going from 1800m water depth at the P-52 location to 100m water depth at PRA-1. The installation was finalized on October 2007. This paper describes the studies carried out to confirm the concept feasibility for such application and explains the main features of the design that takes best advantage of local practices and Petrobras capabilities. Initially a MODU was considered for the deployment of the FSHR system. However, as an outcome of the bid process, a pipelay and construction vessel would be utilized instead, for installing the system. Moreover, the subsea equipment and derivations would be designed considering a new engineering conception of independent and retrievable modules connected at the base, named In Line Structures, therefore precluding the need of a certain number of PLETs and rigid jumper installations, thus optimizing the operation. Some of the engineering analyses performed for the design development, for both installation and in-place conditions, are described in this text. The fatigue damage due to Vortex Induced Vibration proved to be an important driver for the Hybrid Riser design. Vortex Induced Motions of the Buoyancy Can were also a significant source of fatigue damage to the system. The rigid base jumper, connecting the riser base to the pipeline is another special component of the system, and a brief explanation of the design issues is provided. Key issues such as crossing design and thermo-mechanical analysis are addressed as well as the development of mitigation solutions to overcome the thermal effects on the pipeline.