Abstract

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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