Contreras, D.R., Paul Mann, Alejandro Escalona, and Miguel Nuñez
Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, C1140, Austin, TX

The supergiant Maracaibo foreland basin of western Venezuela forms a northwest-trending, 3-4-km-thick asymmetrical wedge of mainly Eocene sandstones along the northeastern edge of Lake Maracaibo. Most previous studies have focused on the extensive oil pools in Eocene and Miocene fluvial-deltaic reservoirs located near the lake's western edge and in the basin center. The northernmost area of the lake and the area near the city of Maracaibo have remained relatively unexplored. In this presentation, we use a grid of 711 km of 2D seismic data integrated with 13 wells to constrain the structure and stratigraphy of this part of the foreland basin. These data show that the large asymmetric basin extends beneath the study area with an average thickness of 4-km. Thick fluvio-deltaic sandstones are found in the area, similar to those Eocene sandstones packages producing in the center of the basin.

The Icotea and Urdaneta Eocene strike-slip faults of the basin center extend into the study area and exhibit positive flower structures. Subsidence analysis of well data show that the main pulse of subsidence occurred in late Paleocene to early Eocene time and reveals that Cretaceous carbonate platform (and the La Luna source rock) was buried to depths of up to 4000 meters. Burial histories indicate that the source is in the gas window or is overmature. The presence of a few producing gas wells over the top of the flower structures in the area supports the gas window calculation and opens opportunity for exploration along the main faults.