The Riser System Challenge for 1,800 Meters: Roncador Field, Offshore, Brazil

The paper presents a general overview of the technological challenge posed by the development of the phase 2, module 1A of Roncador field, offshore, Brazil. The field, discovered in 1996, encompasses reserves of 2.1 billion barrels of oil equivalent and is being developed in phases. This second phase, module 1A will be developed using solutions that will be among the world’s larger semi-submersible floating production unit displacement of more than 80,000 tons named Petrobras 52 (P-52). The platform will be moored in 1,800 meters (5905 ft) water depth. Peak production rates are targeted at 180,000 barrels per day (28,618m3/day) of oil and 130 million cubic feet per day (3.7 million m3/day) of natural gas. In addition to oil and associated gas processing capability to export and gas-lift, the unit will provide facilities capable of injecting up to 302,000 barrels per day (48,000 m3/day) of water. The subsea system was devised with all wells wet completed and directly connected to the production unit through around 44 SCRs (steel catenary risers) as base case. Moreover, alternative riser solutions such as flexible and hybrid risers are being screened and should be considered in the construction and installation bid. The gas lift system was defined through three subsea manifolds in order to narrow down the number of risers. The oil and gas export system was envisaged to be done through large diameter pipeline up to a shallow water fixed jacket hub facility which is linked with shore refinery pipeline network. The platform is scheduled for initial production in 2006. The feasibility study for the second phase, module 1A was performed in the third quarter of 2001. The main challenge was to produce an appraisal that mitigates the technology risk and also provides enough robustness to guarantee an attractive return rate. The unique field proven technology available to be considered in the feasibility study for the riser system as base case was the steel catenary riser system. On the other hand, other technologies were also investigated such as the riser tower system — similar to Girassol, West Africa; flexible riser system — to be qualified and the sub surface buoy, an in house solution. This paper describes the technical approach used into the feasibility in-house study that established the design base for the base case as well as the alternatives.