--> ABSTRACT: Seismic Stratigraphy of the Deep-Water Area in the Northern Orange Basin, Offshore South Africa, by Salomo, Jonathan; #90135 (2011)

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Seismic Stratigraphy of the Deep-Water Area in the Northern Orange Basin, Offshore South Africa

Salomo, Jonathan 1
(1)Resource Evaluation, Petroleum Agency SA, Cape Town, South Africa.

The petroleum potential off South Africa’s west coast margin has been widely studied in recent years, but has largely focused on the shelfal areas where most of the acquired data exists. These studies led to a comprehensive understanding of the shallower water depositional history and systems which in turn aided the identification of several petroleum plays along the margin. With the focus of petroleum exploration shifting more and more to deep-water areas in recent years, it becomes pivotal to expand our knowledge of these depositional systems with the focus on source and reservoir facies. With the proven success of seismic stratigraphy methods in the identification of regional scale plays, it provides a key input for the development of leads to drillable prospects.

This research presents the seismic stratigraphy of the sedimentary succession of the deep-water areas in the northern parts of the Orange Basin, off the west coast of South Africa. The seismic data used for this study includes a set of good quality PSTM 2D lines located within water depths of between 1000m and 3500m combined with well data from the nearest wells. The workflow is based on the classic approach of delineating subsurface stratigraphy through the interpretation of reflection seismic data and the integration of well-log and core data.

Several basin-wide sequence boundaries previously mapped on the shelf were correlated well into the deep-water areas. The westward-thinning, post-rift sedimentary wedge can be subdivided into several seismic units. These comprise mappable sequences of Late Hauterivian, Barremian to Aptian and Cenomanian to Turonian claystones with source potential, complimented by several submarine basin floor systems at different stratigraphic levels. The potential for stratigraphic and/or combination hydrocarbon plays is high throughout the study area. The results of this study provide a strong basis for correlating the well-known shelfal areas with the relatively under-explored deep-water areas of the northern Orange Basin, in terms of the identification and prediction of the location of reservoir, source and seal facies. The study results also allow for the integration of the nearly resolved depositional history of the western parts of the basin with that of the shallower parts in the east.

 

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.