Depositional Model of a Palaeo-Orinoco Shelf Margin Delta System, Columbus Basin, Trinidad

Ramiz Israel
BP Trinidad and Tobago, Port of Spain, Trinidad and Tobago

High resolution seismic imaging below the present day shelf margin of the Columbus Basin and Plataforma Deltana, provides new understandings of the interaction of active tectonics, fluvial process, and the accommodation space fluctuations that influence deltaic and shelfal architecture.

3D seismic data images remarkably the most recent (18,000 - 12,000yr) shelf edge deltaic system which is seen as a prograding sigmoid oblique clinoform bundle that represents the most significant period of sediment accumulation. The package highlights the syn-depositional tectonic influence on the deltaic architecture in terms of accommodation space creation.

Internal seismic facies represent different depositional environments of the shelf edge delta system. These facies are categorized into five divisions: (1) proximal topset, (2) topset, (3) high angle clinoforms, (4) low angle clinoforms and (5) low amplitude layer cake facies. In each of these, sub facies were used to describe in more detail differing depositional processes and potential petroleum reservoir facies from the coastal plain, across the shelf margin and into the upper depositional slope.

The system has successfully been used as an analogue for the controls on shelf margin architecture at deeper stratigraphic levels in the Columbus Basin.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005