--> Abstract: Tertiary Reservoirs in Congo-Kwanza-Namibe Basins, by A. Raposo and M. Inkollu; #90933 (1998).

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Abstract: Tertiary Reservoirs in Congo-Kwanza-Namibe Basins

Raposo, António and Inkollu, Murthy - Sociedade Nacional de Combustives de Angola

Years of exploration efforts in the Congo and Kwanza basins lead to recognition of sand reservoirs in Eocene, Oligocene and Lower-Middle-Upper Miocene. These are ascribed to channel, delta, pro-delta and, basin-floor fan setting. Twenty-five years of significant exploration in these reservoirs has been an impetus for the current onset of major discoveries in deep offshore.

Exploration efforts are lucrative in the Congo, Kwanza and unexplored Namibe basins. Within these, a prolific Tertiary hydrocarbon system is recognizable in distinguishable traps, generative source beds, migration pathways and seals. These are elucidated with selective examples.

A parameter profile for the different reservoir setting shows the commercial validity, even at smaller accumulations, 3D seismic technology, AVO have further enhanced the reservoir identification. DHI's, such as flat spots, phase change in amplitudes have a proven record in the reservoir identification.

In the basins, the Tertiary depocenter differs in significant proportions. Maximum thickness is in the Congo Basin (@ 6000M), intermediate in the Kwanza Basin (@ 3500M) and, minimum in the Namibe Basin (@ 2500M). This variation is attributable to the role of tectonism at the margin. Also, rivers have influence in the rate of sediment discharge. It has a further bearing on the reservoir exploration targets for each basin. Salt diapirism is a key factor on the sediment distribution pattern and localization. Major anomalous zones for Tertiary reservoir exploration are indicated in the open concession areas.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil