Extended Families: Predicting and Correlating Lacustrine Sourced Oils in a Pre-Salt Play, Santos Basin, Brazil and Along the Eastern Brazil Margin
William Dickson1, Craig Schiefelbein2, and Mark E. Odegard3
1Dickson International Geosciences (DIGs), Houston, TX
2Geochemical Solutions International, Shenandoah, TX
3Grizzly Geosciences, Inc. (GrizGeo), Sugar Land, TX
In a 2005 poster at AAPG Calgary, the authors integrated geochemistry with detailed g&g mapping and revealed the potential for oil trapping on the unexplored south flank of the Santos basin. Pre-salt basins and even individual paleo-lakes were imaged, migration pathways were defined, the limits of different petroleum systems were mapped and we predicted a pre-salt play in Brazil's Santos Basin.
With a subsequent series of significant discoveries, it was time to test predictions against facts. Aided by the development of more and better data, we re-examined the earlier correlations first within the Santos Basin and then along the eastern Brazil margin where similar data provided reasonably analogous conclusions. Some key findings related to widespread evidence for lacustrine-sourced oils, frequently partially masked by multiple phases of migration from the same source type or from younger marine source intervals. Many structural compartments could be mapped from potential fields data, then correlated to geochemical indicators from oil samples and piston cores. These compartments showed subtle variations among a small number of basic oil families with distinct terroirs.
Family trees constructed by sorting oil indicators in multivariate space demonstrated genealogical extents while potential fields, piston cores, remote sensing, literature and other material illustrated spatial extents. We provide examples of both to demonstrate our interpretation of the lacustrine kitchens of the Santos Basin versus the recent discoveries; and of the related basins along the eastern Brazil margin.
AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas