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Abstract: Petroleum System of the Barua and Motatan Fields and the San Pedro--Machango Area

Alonso Navarro, Felix Diaz, Ivan Rodriguez

The study area is located in the Costa Bolivar (onshore) in the Maracaibo Basin, being framed by Ceuta (offshore) and Tomoporo fields to its west and the Valera fault zone to the east, Mene Grande field to the north and La Ceiba to the south. Eocene oil accumulations are the most important for the study area. Probably this oil was generated and migrated during Miocene-Holocene time. Heavy oil accumulations occur in Miocene intervals, although they have not been considered commercial. It is possible that this oil was generated during early to late Eocene and suffered later biodegradation and remigration. Structurally, it is characterized by different and highly complex tectonic events. Normal faulting occurred during Cretaceous and Eocene times. During the latter, periods f inversion were present that created structural highs where oil generated from La Luna Formation (Cretaceous) accumulated. Major structural deformation occurred during upper Eocene and lower Miocene (Andes uplift). This deformation shows an increase from west (Barua) to east where the Valera fault zone is present. The study area shows a regional dip towards the south, while during the Eocene it dipped towards the north, due to the foredeep condition of the area, when up to 15,000 ft of sediments were deposited, based on seismic data. Porosities vary from 8% to 18% within the area. Fractures are present and they enhance oil production.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela