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Prospectivity of the Portuguese Deepwater Areas Within the Context of the Afro-European East Atlantic Province

Pimentel, Nuno1 and Pena dos Reis, Rui B.
1[email protected]

The eastern coast of the Central and North Atlantic is being looked by several companies as a promising region for deepwater oil and gas exploration, including the deep offshore areas of Mauritania and Morocco, in Northern Africa, and Portugal and Spain in Western Europe.

In Mauritania, the Coastal Basin extends into deep offshore, presenting important Tertiary leads, with some producing areas (Chingueti Field) and several prospects with significant oil and gas shows.

In Western Morocco, several deep offshore leads have been identified, considering two main source rocks (Toarcian and Aptian) and Lower Cretaceous reservoirs.

The Portuguese deep offshore presents two distinct sectors, one facing the North Atlantic and the North-American coast and another along the connection between the Mediterranean and the Atlantic, facing the Northern Morocco coast.

The Western Iberian margin resulted from the Western Tethys and N.Atlantic evolution, with a thick Late Triassic to Neogene infill. Along its 1000 km long N-S section, some important differences may be noted in the timing of the main rift events and both Mesozoic and Cenozoic sediment thicknesses. Seismic scale observations suggest an earlier rifting and a more pronounced

Tertiary subsidence and infill for the Southern sector (offshore Alentejo Basin), whereas the Northern Sector (Peniche Basin) seems to have a more recent rifting and less recent subsidence and infill. This contrast may point to a better development of the Cretaceous-Cenozoic play in the S, related with the Mediterranean and North African mainly Tertiary play, and of the Jurassic play in the N, related with a North Atlantic mostly Jurassic play.

At the southern Portuguese margin (Algarve Basin), two superimposed basins may be considered – a L.Triassic to E.Cretaceous Tethys related basin and a L.Cretaceous – Neogene Betic-Guadalquivir related basin. In the deep offshore, both a Mesozoic and a Tertiary play may be active.

The Portuguese deep offshore is part of a larger deepwater province, where two main plays are well represented: i) a Mesozoic play with different source-rocks (E. Jurassic, L.Jurassic and U.Cretaceous ?) and mainly E.Cretaceous reservoirs; ii) a Tertiary play with the same source-rocks and Cenozoic reservoirs. The detailed knowledge of the source-rocks and its maturation, as well as the distal extension and properties of the Cretaceous to Tertiary siliciclastics, are therefore crucial to address this deepwater province.

 

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013