Abstract: A New Paleogeographic Interpretation of Barinas Basin, Western Venezuela, During Eocene
Mounir Mahmoudi, Luisa Figueroa, Clara De Guerra, Zorena De Monroy
During the Eocene, the Barinas Basin has been considered an uniform, almost flat platform tilted in a north-northeast direction, with a considerable paleobathymetry increase. This paleogeographic interpretation agrees with the middle-late Eocene sedimentation (Paguey Formation), when the marine transgression was at its highest point. New exploratory data show that the beginning of the middle Eocene sedimentation was not uniform. Facies changes and thickness variation from 50 to 270 ft have been interpreted. Sedimentological and biostratigraphic analysis of cores from the Eocene reservoirs show a remarkable facies variation: coastal, estuarine, beach, and reefal facies. Based on cores data and the seismic lines passing through the cored wells, a paleogeographic map was con tructed for the lowermost Eocene section. The information was tied to other seismic lines. This methodology allowed us to divide the area into a series of high and low topographic zones, as well as the identification of a belt of highs trending northwest-southeast which includes the five exploratory wells. One of them is located on a reefal high which is separated from the other wells by areas of low zones or grooves. The high belt separates two low areas of meandering incised valleys, trending in the same direction. Three wells penetrate these paleovalleys. This new paleogeographic interpretation explains the distribution of the different facies and thickness variation of the Eocene reservoirs, which suggest that the Eocene sedimentation was influenced by sea level changes and by region l tectonics.
AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela