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fax 01-972-952-9435. AbstractAfter producing 400 million barrels of oil along the last five years, Marlim Sul field, situated in Campos Basin, Brazil, applied its first time-lapse seismic acquisition. The oil is being produced from six different reservoirs, each one with different characteristics. The main common point of them is the water drive mechanisms, and therefore the flow path of the injection water is the prime purpose of this 4D action. Almost all producers have seen the breakthrough of water, sometimes after the forecasted time, sometimes before. The seismic data were acquired by a streamer steering system and received special attention in terms of velocity analysis and crossequalization process. The preliminary analysis indicates some interesting conclusions. The water path seems to be less regular than expected from flow simulation and indicates a trend in rock permeability. This knowledge allows a better match of the model, and a better control of production and injection rates. In addition, some areas are less flooded than expected, wich permits the proposal of new infill drillings, in order to recover this additional oil, depending on the economic analysis, as well as a new infill well, proposed before the acquisition, is not in the better position, and may be relocated or cancelled. Furthermore, the communication of two blocks, situated one above the other, was strongly suggested by the presence of an anomaly related to increase of gas saturation in the higher block derived from the depletion of the lower one. These simple conclusions reveal the power of time-lapse seismic acquisition, and evidence the importance of a permanent reservoir monitoring for the optimization of recovery factor and the profitability of the exploitation project.

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A superior depth-migration solution that uses all the recorded data, including primaries and all orders of multiples, can be adapted from towed-streamer acquisition to ocean-bottom cable (OBC) or ocean-bottom node (OBN) acquisition. The technology has been validated using the 3D/4D data sets acquired by Petrobras for the deepwater Jubarte PRM pilot in Campos Basin. Images constructed from primaries and all orders of sea-surface reflections shows improved subsurface coverage when compared with images from primaries alone and/or mirror migration. The resulting 4D signal also shows a good match with the well trajectory, validating the use of this novel technology for 4D imaging studies.

This paper will focus on the strong impact that seismic technology has had on the production development of the Brazilian marine oil fields starting from the first oil discovery in 1968 (Guaricema field) to 2006, when the pre-salt new province was revealed in Santos basin. The evolution of three main knowledge areas of seismic technology will be detailed, namely: acquisition, processing and interpretation. Seismic acquisition technology has experienced an increase in "information density" (seismic traces per square kilometer) which grew by one order of magnitude (from less than 100,000 to 1,024,000), from 1978 (first 3D in Brazil) to 2010. In the seismic processing domain, the improvement of seismic algorithms and methodologies has allowed for better seismic data quality, resolution and imaging. In particular, the algorithms/techniques of 3D multiple suppression and 3D depth migration have significantly evolved in recent years. In the seismic interpretation area, geological context-oriented seismic attributes algorithms/methodologies have made possible better reservoir characterization and monitoring in the deep and ultra deep-water Brazilian offshore basins.Advanced Seismic Imaging Impact This work will not limit the concept of Advanced Seismic Imaging-related technologies to the classic development of seismic migration-oriented methodologies and algorithms as traditionally perceived by the seismic processing area. It seems to us that the advanced seismic imaging technology capable of correctly impacting the development of oil reservoirs would be better understood if viewed as an integrated complex to include acquisition, processing and interpretation technologies. This will provide us with a more adequate and systemic view of the real impact of the evolution of these technologies on the development of Brazil's offshore oil fields. A brief historical evolution will be outlined below together with the identification of significant technological milestones in each of the respective seismic activity areas in the Brazilian coast. Greater emphasis will be placed on results of the last 10 years when Petrobras made the decision to invest in high-density data (>1,000,000 traces/km 2 ) for use in the characterization and monitoring of turbidite reservoirs and also decided to invest in multicomponent seismic technology with a sizeable initial portfolio of 3C and 4C projects. We will also mention the company's initial efforts to improve the seismic imaging of the recently discovered (2006) reservoirs of the new pre-salt oil province. Huge efforts in seismic data acquisition and processing have been put forth both by Petrobras and service companies in this new oil province so as to enhance the seismic imaging of this area. The Brazilian pre-salt reservoirs have their own specific geological and geophysical characteristics which differ from those displayed by the sub-salt reservoirs of GOM and other sedimentary basins of the world. In view of this, new seismic technologies encompassing the three general knowledge areas namel...

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