Abstract: Source and Reservoir Rock Factors Tertiary Hydrocarbon Accumulations and Basins of Coastal South America

By

David A. Fontaine

Pacific and Caribbean coastal Tertiary basins of South America exhibit a wide variety of clastic fill. Some basins are sand-starved relative to others which are sand-rich. These differences cannot be explained by utilizing the classical tectonic-sedimentary approach of source area relief, distance tectonic intensity or lithology. Many of the basins studied are approximately equal with respect to these factors but contain markedly different fill. Caribbean basins tend to be sand-rich, while Pacific basins are usually sand-poor.

The potential for high organic content in shales of these basins appears fairly uniform when based upon the occurrence of oceanic upwelling zones during the Cretaceous - Tertiary. The Pacific and Caribbean areas appear to be sites of greatest potential, the Atlantic basins less so.

Oceanic and atmospheric circulation appears to have played a significant role in influencing the distribution of potential source rocks and may have acted as the controlling factor over the processes responsible for the generation, transport, and deposition of reservoir sandstones. By mapping these circulation patterns on paleogeographic maps, it is generally possible to predict in advance of drilling, those basins that should contain the fortuitous combination of potential source rocks and reservoir sandstones, and those that should not. Case studies of oil fields and basins along western Ecuador, Peru, Chile, northern Columbia, Venezuela, and eastern Brazil are discussed.

End_of_Record - Last_Page 4---------------

Copyright © 2005 by Houston Geological Society. All rights reserved.