Barracuda and Caratinga giant oil fields, deep water Campos Basin, Brazil
Authors: Assis Osrnar C. , Becker Mauro R. , Melo Jose R.C. , Franz Enio P. , Alves Ricardo R.P. , Rodriguez Monica R. , Maciel Walter B. , Souza Olinto G. , Johann Paulo R.S. 
Published: October 2008

The Barracuda and Caratinga oil fields contain a combined in place volume of 4,100 MMBOE, and total reserves of 1,200 MMBOE. They were discovered in 1989 and 1994, respectively, in the south-central Campos Basin after a successful 3D seismic-based exploration in deep water. In these fields, seismic attribute analysis discriminates oil saturated Paleocene, Eocene and Oligocene sandstones encased in shales and marls. The reservoirs are turbidite sandstones, deposited in bathyal settings controlled by halokinetic-generated depocenters and grabens. The fields will be jointly developed due to their geographic proximity. A pilot production system composed of 12 wells started production in September, 1997. Future plans include ore three phases: Phase 1 will take place in the Barracuda field in water depths less than 950 m, where geologic uncertainties are smaller; Phase 2 includes the area of Caratinga field, in water depths less than 1050 m; and Phase 3 will cover deep-water areas of both fields. The Barracuda and Caratinga fields will be developed essentially with horizontal wells (44 in Phase 1,24 in Phase 2 and 3 1 in Phase 3), and 2 1 verticals wells (3 new and 18 already drilled). This paper presents the reservoir characterization, development strategy and production plans for the fields, which were prepared by a multidisciplinary team of reservoir geophysicists, geologists, and engineers. This report focuses on the Phase 1 of Barracuda field, which includes almost half of the wells to be drilled, and will be responsible for an estimated production of 270,000 BPD.

Introduction

The Barracuda and Caratinga oil fields are located in the south-central portion of the Campos basin, about 90 km offshore of Rio de Janeiro State, Brazil, at water depths ranging between 600 and 1200 m (Figure 1). These two giant oil accumulations cover a total area of about 234 km2, and contain in place volume of 2,700 and 1,400 MMBOE and total reserves of 780 and 420 MMBOE, respectively. The oils of the fields are 25 and 24 degree API, respectively. The Barracuda and Caratinga fields were discovered in 1989 and 1994, respectively, after a successful seismic-based exploration campaign by PETROBRAS in deep waters of the Campos Basin. During the exploratory phase, PETROBRAS drilled 16 wells in Barracuda (4 wildcats and 12 appraisal wells) and 10 wells in Caratinga (2 wildcats and 8 appraisal wells). The large number of appraisal wells indicates the complexity of the fields. Seventeen wells of these will be producers and one well will be a water injector. Some will be used during a pilot production phase in the monitoring of reservoir behavior. The future development and production plan for the areas is divided into 3 consecutive phases. From the 102 news wells planned to be drilled, 52 will be as producers and 50 as water injectors.

Geologic Reservoir Characterization

The Barracuda field has 4 stacked reservoirs of Late Paleocene, Middle Eocene (2 zones) and Late Oligocene age (Figure 2). All are turbidite sandstones from the Marine Regressive Megasequence (Guardado et al. 1990), deposited in bathyal settings controlled by halokinetic-generated depocenters and grabens (Figure 3). The main oil zones of the Barracuda field are the Oligocene reservoir with 1,500 MMBOE (55% of the original oil-inplace) and the lowermost Middle Eocene reservoir with 830 MMBOE (31% of the 001P).