TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAlbacora Leste, one of the largest Campos Basin deep-water oilfields, was discovered in March of 1986. Oil field development area involves 141km 2 and water depth ranges from 800 to 2000m. In order to exploit the field, 30 horizontal wells -16 producers and 14 injectors -will be connected to an FPSO unit (P-50). Expected total reserves are 565 million barrels of oil.Albacora Leste main reservoirs are Miocene sandstones with high porosity and permeability. The depositional model is interpreted as a complex turbidity system, mainly represented by channels, lobes and overbank facies. Net thickness ranges from 5 to 35m, suggesting horizontal well drilling. After the deposition stage, erosive channels introduced flow barriers that generated different reservoir compartments. These compartments impacted drainage pattern design and were checked through reservoir pressure data after long term pilot well production, log interpretation, and fluid samples analyses. Small gas caps showing different gas/oil contacts were detected all over the field area, introducing an additional challenge for field development.Intensive application of the following technologies was important to make field development technically and economically successful: (1) high quality 3D seismic; (2) image logs and LWD (logging while drilling); (3) long gravelpacked horizontal wells; (4) thermally insulated flowlines, allowing flow assurance for distant satellite wells; and (5) massive sea water injection for sweep, and reservoir pressure maintenance. In order to avoid scale deposition as a result of sea water injection, a Sulphate Removal Unit was installed in the P-50 FPSO.This paper presents the key aspects of the reservoirs, the drainage modeling and design, as well as the strategy adopted during project implementation, in order to overcome main reservoir uncertainties, such as fluid type, connectivity, and net pay, accomplishing at the end a successful project execution.

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Petrobras has been developing its 4D seismic technological programme since 1998, focused on the Brazilian deep-water fields in the Campos Basin, and considering the technical, operational and economic challenges involved in the development plan and reservoir management in this environment. The first step was to align the objectives of the project with the company goals for the following 15 years, in terms of earnings growth, production growth and reserves replacement. This information guided how the 4D reservoir management should be employed: as hedging technology to ensure that production targets would be achieved in several key fields at once, or as a direct technology investment to increase the production of individual, independent fields. The mission of reservoir management for each field involved was understood and new deep-water seismic technologies were developed to face the global operational and economic targets. 3D seismic reservoir monitoring, or 4D seismic study, was defined as an ‘integration of multidisciplinary technologies that includes the time-lapse monitoring of the drainage efficiency, using cores, well logs, seismic data, production history and pressure management’. Water injection is the preferable recovery method for the deep-water reservoirs in Brazil. Therefore, seismic monitoring should be able to distinguish contrasts of both fluids – injected water and remaining oil – that normally produce small seismic impedance values. This characteristic has brought the first technical challenge: the use of the 3D P-wave surface legacy data from the 1980s and 1990s, when the major fields started production, as 4D base-volumes to be correlated with future recommended 3D seismic data (surface or ocean bottom systems) as 4D monitor-volumes. In addition to all developed seismic technologies for data processing, a general 4D work flow was designed and the concept of the integrated reservoir model was adapted to relate all such technologies to the reservoir engineering needs and to the field economics, generating reliable 4D images for each reservoir study. This paper summarizes the multidisciplinary technical integration, including geological and seismic modelling, petrophysical simulations, seismic processing and interpretation, and reservoir simulation. A 4D methodology was implemented to integrate all such technical development and economic analysis, identifying where, when and how seismic monitoring can contribute to the reservoir management. This methodology has been applied to the Campos Basin deep-water reservoir, Rio de Janeiro State, Brazil.

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