Assessment of the oil source-rock potential of the Pedregoso Formation (Early Miocene) in the Falcón Basin of northwestern Venezuela |
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| Authors: | Jean Carlos Montero-Serrano Manuel Martínez Armelle Riboulleau Nicolas Tribovillard Gonzalo Márquez José Vicente Gutiérrez-Martín |
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| Institution: | 1. Instituto de Ciencias de la Tierra, Universidad Central de Venezuela. Apartado Postal 3895, Caracas 1010-A, Venezuela;2. Université Lille 1, Laboratoire Géosystèmes, UMR 8157 CNRS, bâtiment SN5, 59655 Villeneuve d''Ascq cedex, France;3. Departamento de Ingeniería Minera, Mecánica y Energética, Universidad de Huelva, Palos de Fra., 21819 Huelva, Spain |
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| Abstract: | The early Miocene Pedregoso Formation is one of the numerous formations rich in organic matter within the stratigraphic record of the Urumaco Trough, in the central area of the Falcón Basin. Due to its lithological characteristics and stratigraphic position, this formation is of great interest regarding the basin's petroliferous systems. The evaluation of various inorganic and organic geochemical parameters indicates that the organic matter is primarily of marine origin, deposited in a marine carbonate environment typical of reefal systems, under oxic-to-dysoxic conditions. The low variability in the TOC concentrations and in the distributions of the biomarkers extracted from the samples suggests that the paleoenvironmental conditions and the organic-matter supply remained approximately constant throughout the sedimentation of this unit. The Pedregoso type-II organic matter (marine origin) and initial organic richness value (∼1.8%) suggest that this unit has probably generated hydrocarbons within the Urumaco Trough. However, present-day thermal maturity parameters reveal that the Pedregoso organic matter is overmature (dry gas window), indicating that this unit is only capable to generate gas. In addition, the geothermal gradient, maturity parameters, and the maximum paleotemperature estimated in this study suggest that the Pedregoso Formation reached a maximum burial depth the ∼6.5 km, consistent with the value obtained from data of stratigraphic thickness in the Urumaco Trough. This implies that the thermal anomaly that affected the basin during the Late Eocene–Early Miocene did not reach the central part of the basin, and therefore, the organic matter maturation in this unit is due to the sedimentary burial. |
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| Keywords: | Geochemistry Biomarkers Redox conditions Carbonate turbidites Organic matter Thermal maturity Catagenesis Venezuela Falcó n Basin |
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