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Bernardo, Luis M.1, Adry Bissada2
(1) GEOCINTEG, C.A, Caracas, Venezuela
(2) University of Houston, Houston,

ABSTRACT: Petroleum System Analysis of the Orinoco Platform, Offshore Eastern Venezuela

This study entails analyses of the Orinoco Platform and the Venezuela Atlantic Margin petroleum system in order to understand the effects of the physico-chemical and geological conditions on hydrocarbon generation, expulsion, and entrapment within the systems. We inferred the existence of adequate oil-prone source rocks within the Upper Jurassic and Upper Cretaceous sequences, and oil- and gas-prone source rocks within the Lower Cretaceous and the Lower Miocene. However timing of thermal maturation and constraints on hydrocarbon preservation narrowed down the probability of effective source rocks within the Upper Cretaceous.
Effective hydrocarbon expulsion from Upper Cretaceous source rocks within the generative basins could have begun about 15 Ma ago along the Venezuela Atlantic Margin, and about 4 Ma ago along the Orinoco Platform. Migration of hydrocarbons would have occurred principally southwards into the Orinoco Platform and the Guyana Basin. However significant volumes could have migrated into possible stratigraphic traps in the Venezuela Atlantic Margin. Volumetric analysis of hydrocarbon charge from the Upper Cretaceous source into two hypothetical prospects suggests that under the most favorable of assumptions, the maximum amounts of hydrocarbons available for entrapment within the Orinoco Platform prospect would be about 37 TCF of gas and 52 billion bbl of oil and within the Venezuela Atlantic Margin prospect would be 190 TCF of gas and 94 billion bbl of oil. The differences stem from differences in the quality, volume, and maturity of source rocks and in size and properties of the carrier systems within the migration pathways.

 

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