Main Challenges and Uncertainties for Oil Production from Turbidite Reservoirs in Deep Water Campos Basin, Brazil

Carlos H. Bruhn, Antonio Pinto, and Paulo R. Johann
Petrobras E&P, Rio de Janeiro, Brazil

Deep and ultra-deep water giant fields started to be discovered in the Campos Basin in 1984. There was a succession of large discoveries, such as Albacora, Marlim, Albacora Leste, Marlim Leste, Marlim Sul, Barracuda, Caratinga, Roncador, Jubarte, and Papa Terra. The development of these fields has continuously provided new challenges for the reservoir characterization and management. These fields are developed with fewer, horizontal and high angle wells, drilled into poorly consolidated reservoirs. The extensive use of 3D seismic as a reservoir characterization tool has optimized well location and allowed the reduction of geological risks. Integration of high-resolution stratigraphic analysis with 3D seismic inversion, geostatistic simulation of reservoir properties constrained by seismic, well log and core data, and 3D visualization has guided the positioning of horizontal wells through thin (<10-15 m) reservoirs. Additionally, 4D seismic have provided a new tool for reservoir management, where seismic, well logs, cores, and pressure/production data are integrated into much more detailed and robust geological and fluid flow models. The deepwater subsea wells must be designed to allow high production rates (typically >10,000-20,000 bopd). In order to assure high productivity, pressure maintenance must be efficient; if water injection is planned, the hydraulic connectivity between injector and producer wells must be guaranteed by high-quality 3D seismic, well log correlation, and observed pressure profiles. Detailed studies have been made in order to define the distribution and number of wells, since the number of wells strongly affects the net present value of deepwater projects. Wells with expected oil recovery of less than 10-20 million bbl are not drilled in the beginning of the projects, and remain as future opportunities to increase oil production and recovery.

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