Paper No. 19
Presentation Time: 9:00 AM-6:30 PM


SOLORZANO, Verioska1, BECERRA Sr, Jhony2, CAMACHO, Pedro1, VALBUENA Sr, Edwin2, ZAVALA Sr, Carlos3, ARCURI Sr, Mariano3, ZORZANO Sr, Agustin3 and DI MEGLIO Sr, Mariano3, (1)Gerencia de Exploración y Estudios Integrados de Yacimientos, PDVSA Guaraguao, Puerto La Cruz, 6023, Venezuela, (2)Laboratorio Geológico, Exploración Occidente, La Concepción, 4032, Venezuela, (3)Geologia de Cuencas Sedimentarias, Bahia Blanca, 8000, Argentina,

The Cretaceous-Neogene Macaraibo basin in Venezuela is one of the most prolific petroleum basins in the world. The southern end of this basin is part of the Merida Andes, a highly complex tectonostratigraphic province resulting from the interaction of Andean and Caribbean geodynamic framework. Several oil seeps were early recognized in this area, which encouraged a shallow drilling campaign during the twenties, (seven wells) with unsuccessful results. More recently, during the nineties, three deeper wells were drilled, registering almost the entire stratigraphic column (some reaching the basement). These wells revealed a very complex and poorly understood tectonic scenario and a drastic miscalibration with the expected stratigraphic.

A regional field study was recently performed over an area of 3900 km2, aimed at reducing the risk of future drilling campaigns. The study was focused on obtaining a better understanding of the stratigraphy, structure and petroleum system. All field data was registered and processed using an original digital procedure. Fourteen stratigraphic columns (> 2000 m) were measured, analyzed and sampled in detail. Field gamma ray was run in all sections allowing the detailed calibration with well logs of existing wells. Field surveying provided more than 660 structural and stratigraphic control points. Main reservoir and source rock units were sampled (petrography, petrophysics & geochemistry) in order to obtain a better estimation of the oil potential of the entire area. Additionally, all identified oil seeps were sampled when there was possible.

New stratigraphic and structural data obtained during this study, allowed the update of existing regional maps, resulting in a more confident GIS-based geological map. The integration of field data with 2D seismic permitted the construction of two regional geological sections. Additionally, new stratigraphic data allowed the detailed calibration on existing wells, resulting in a new and more accurate stratigraphic schema for the area.

Field studies appear as a low cost and very useful tool for reducing the exploration risk in very complex geological areas.