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Dickson, William G.1, Craig F. Schiefelbein2, Mark Odegard3
(1) DIGs, Stafford, TX
(2) Geochemical Solutions International, Inc, Woodlands, TX
(3) GETECH, Stafford, TX

ABSTRACT: Hydrocarbon Neighbourhoods and Migration Limits: Results from Co-interpreting Geochemical and Geophysical Data in Brazilian Basins

Abstract The continental margin basins of Brazil and West Africa contain prolific oil habitats. Most historic production has been generated from lacustrine sediments deposited during Neocomian rifting (Brice, et al. 1980, Mello et al. 1988a and b; Burwood 1997; and references therein). Increasingly important are Late Cretaceous post-evaporite sediments with liquid hydrocarbon source potential laid down in shallow marine and fluvial-deltaic environments as spreading continued (Mello et al. 1988a and b; Sofer 1993; Burwood 1997; Katz et al. 1997; and references therein).
This investigation began as an analysis of South Atlantic Margin basins using both geophysical and geochemical data with software to generate paleo-reconstructions of all the data sets. The initial rough set of correlations between conjugate basins based on a large set of crude oil data suggested missing source rock plays by highlighting a series of oil family matches and gaps along the margins. Unexpectedly, the oil families seemed in each basin or sub-basin to relate closely to structural elements imaged from regional gravity data.
The recent availability of higher resolution gravity and magnetics grids allowed detailed correlations in four Brazilian basins (Campos, Espirito Santo, Reconcavo and Sergipe-Alagoas), dramatically reinforcing the definition of source kitchens and transfer faults or zones of weakness that separate oil types. By combining data sets, we have imaged basins and even individual paleo-lakes, defined migration pathways and mapped the limits of different petroleum systems. Our talk illustrates the interpretation process with examples of clear and unclear correlations and explores some remaining questions.


AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.