This article, written by Technology Editor Dennis Denney, contains highlights of paper OTC 19274, "Development of Subsea Facilities in the Roncador Field (P-52)," by Jose Mauricio T.G. Lima, Mariele Lima Kuppens, Paulo Ferreira da Silveira, and Pedro Felipe K. Stock, Petrobras, prepared for the 2008 Offshore Technology Conference, Houston, 5-8 May. The paper has not been peer reviewed.
The second phase, Module 1A, of the Roncador field, offshore Brazil, was developed with a large semisubmersible floating production unit (FPU). This paper explains the strategies adopted by Petrobras to overcome the challenge of starting oil and gas production at a water depth of 1800 m in a short period of time, which required starting the platform construction early, almost simultaneously with the design of the riser system.
Campos basin is offshore Rio de Janeiro State, southeastern Brazil. It covers approximately 100 km2 ranging from 20 to 3400 m water depth (WD). Roncador field lies in 1500 to 1900 m of water in the basin and was discovered in 1996. Development of Roncador field was planned with four production modules. Module 1A comprises two phases of exploitation: Phase 1 began production in 2002 with floating-production-storage-and-offloading (FPSO) vessel Brasil moored in approximately 1300 m WD, to operate some of the wells temporarily. By the end of 2007, the second phase of Module 1A (Phase 2) started to produce to the FPU P-52, which has a total displacement 80,000 t, moored stage of development and knowledge, operational issues, and available resources (e.g., installation vessels). The semisubmersible platform was selected to mitigate the risks of riser development. However, the desire to start Phase-2 production 4 years later required designing and contracting platform construction before the riser system was defined.
Problems faced during qualification testing of flexible-pipe flowlines and risers for Phase 1 raised concerns about the capability of this traditional riser solution for applications in ultradeep water. Therefore, other riser concepts were assessed. The steel catenary riser (SCR) was determined as appropriate technology for the design WD. An in-house technical feasibility study confirmed the SCR as the primary gathering system, while the flexible riser remained an alternative requiring approval in a prequalification program.
The SCR system and flexible risers, after prequalification of the latter with full-scale offshore tests, were both included in the subsea bid for the construction phase. Even though some changes were necessary in the FPU to allow the use of flexible risers, all the provisions for SCRs were kept operational for contingency purposes in the future.