The Marlim and Albacora fields, which are located offshore Rio de Janeiro State in water depths ranging from 250 to more than 2000 m, cover areas of 350 and 235 km² and contain over 14.1 and 4.5 billion barrels of oil in place, respectively. The reservoir rocks of these fields are composed of Albian to Miocene sandstone turbidites.

The Albacora field structure is an anticline feature trending southwest-northeast. The Marlim accumulation combines structural and stratigraphic trapping elements. The reservoir pinches out against marls and shales to the north, west, and south, whereas the eastern, northeastern, and northwestern pool boundaries are defined by normal faults. Albacora is a multiplay oil accumulation whose older reservoirs are located in shallower water depths and whose younger reservoirs are located in deeper water depths. Marlim is a single reservoir oil field but is composed of several pools with different types of oil as a result of the combination of biodegradation and, at least, two phases of oil migration.

The Marlim and Albacora turbidite reservoirs are mostly associated with slope and continental rise deposits. The eastern portions of both fields are dominated by lobe-type sandstones whose successive coalescence resulted in sand bodies with great lateral continuity. To the northwest, these sand bodies become elongated, presenting geometry and facies of typical channel deposits. These channels are thought to be feeders of the lobe system to the southeast.

The development of the Albacora field is being gradually implemented from shallower to deeper waters. It will come on stream in three phases so that each phase will provide information, technology, and cash flow for the subsequent phase. Phase I started in October 1987 and continues presently with a daily production

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of 6000 m³ of oil and 300,000 m³ of associated gas. In the Marlim field, oil production is projected to start from a pilot system designed to identify the parameters needed to determine the final production systems. This pilot will consist of up to 10 satellite wells located in water depths from 600 to 800 m, with subsea completions, and each well will produce separately to a semisubmersible unit moored at a water depth of 600 m. It is scheduled to start in 1992 and is projected at about 8000 m³ of oil and 600,000 m³ of associated gas per day.