--> Abstract: Effects of Tectonic Activity on Sedimentation and Reservoir Compartmentalization, Alto de Ceuta Field, Blocks II, III, IV and VIII, Lake Maracaibo, Venezuela, by E. R. Gustason, E. Gomez, R. A. Ripple, R. Y. Elphick, M. A. Vivas, M. F. Doe, M. Rampazzo, J. de Mena, and J. L. Mora; #90933 (1998).

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Abstract: Effects of Tectonic Activity on Sedimentation and Reservoir Compartmentalization, Alto de Ceuta Field, Blocks II, III, IV and VIII, Lake Maracaibo, Venezuela

Gustason, E. R.; E. Gomez, R. A. Ripple, R. Y. Elphick, M. A. Vivas, M. F. Doe - GeoQuest; and M. Rampazzo, J. de Mena and J. L. Mora - PDVSA

Tertiary sedimentation has been influenced by recurrent motion along the Pueblo Viejo Fault at Alto de Ceuta Field in southeastern Lake Maracaibo. Originally expressed as a down-to-the-east normal fault in the Jurassic and Cretaceous, the Pueblo Viejo has undergone periods of sinistral transpression and partial inversion in the Tertiary. Sedimentation during the Eocene resulted in thicker fluvial, estuarine and marine sediments of the Misoa B and Pauji Formations being deposited to the east of the Pueblo Viejo Fault on the downthrown side. During subsequent Late Eocene-Oligocene uplift the Pauji and part of the underlying Misoa B section were removed over the Alto de Ceuta structure. The missing section includes periods of both erosion and non-deposition and spans approximately 30 Ma at the crest of the structure. The Eocene section is highly faulted, resulting in compartmentalization of reservoirs while associated fracturing has enhanced permeabilities.

The Alto de Ceuta structure was a positive feature throughout Miocene time. Lower Lagunillas, Laguna and Bachaquero members of the Lagunillas Formation are thinned or absent over the feature, the result of non-deposition and/or erosion. West of the Pueblo Viejo Fault the Bachaquero thickens abruptly. While faulting is much less pronounced in the Miocene than the Eocene, changes in sand unit thicknesses and facies due to minor fault relief exert a major influence on reservoir heterogeneity and quality. Understanding the tectonic evolution of the structure and its effects on deposition is leading to a better understanding of the reservoirs in Alto de Ceuta Field.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil