Un vistazo al sistema petrolero de la cuenca de maracaibo

An overview of the petroleum system of Maracaibo Basin
Alejandro Escalona and Paul Mann

AUTHORS Alejandro Escalona  Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 4412 Spicewood Springs Road, Building 600, Austin, Texas, 78759; escalona@utig.ig.utexas.edu Alejandro Escalona is a postdoctoral researcher at the Institute for Geophysics, University ofTexas at Austin. He received his Ph.D. in geology at the University of Texas at Austin in 2003, where he focused on the stratigraphic and structural evolution of the Maracaibo Basin, Venezuela. He is currently interpreting regional seismic and well data from offshore Venezuela to link offshore and on-land Cenozoic depocenters. Paul Mann  Institute for Geophysics, Jackson School of Geosciences,University of Texas at Austin, 4412 Spicewood Springs Road, Building 600, Austin, Texas, 78759; paulm@utig.ig.utexas.edu Paul Mann is a senior research scientist at the Institute for Geophysics, University of Texas at Austin. He received his Ph.D. in geology at the State University of New York in 1983 and has published widely on the tectonics of strikeslip, rift, and collision-related sedimentarybasins. His current focus area of research is the interplay of tectonics, sedimentation, and hydrocarbon occurrence in Venezuela and Trinidad.

ABSTRACT The geologically complex Maracaibo Basin in northwestern Venezuela is one of the most prolific hydrocarbon basins in the world. Having a basinal area of 50,000 km2 (19,300 mi2), the basin has produced more than 30 billion bbl of oil, with estimatedrecoverable oil reserves of more than 44 billion bbl. The central elements of the petroleum system of the basin include (1) a worldclass source rock (Upper Cretaceous La Luna Formation), deposited on a shelf-to-slope environment under anoxic conditions and modified by intermittent oxygenated periods and tectonic events; (2) high-quality clastic reservoir rocks deposited in Eocene and Miocenefluviodeltaic settings; (3) two main periods of rapid tectonic subsidence responsible for two pulses of voluminous hydrocarbon generation, first, during Paleogene Caribbean–South American oblique plate collision and, second, during the Neogene uplift of the Sierra de Perija – Me ´ ´rida Andes; and (4) lateral and vertical migration of oil along strike-slip, normal, and inverted faults, as well as aregional unconformity of late Eocene – Oligocene age. The maturation, migration, and trapping of hydrocarbons were closely controlled by the tectonic evolution of the Maracaibo Basin. During the Paleogene, the development of a foredeep along the northeastern margin of the basin and the strike-slip reactivation of the rift-related Jurassic faults on the Maracaibo platform controlled the earlystructural setting of the source and reservoir rocks. Hydrocarbons migrated updip from source rocks beneath the northnortheastern margin of the basin along north-south strike-slip faults and into overlying Eocene clastic reservoirs in the south-central parts of the basin. The second period of the Maracaibo Basin petroleum system developed during subaerial exposure of most of the Maracaibo Basin duringOligocene –Miocene uplift of the adjacent Sierra de Perija and Me ´ ´rida Andes. Uplift of mountain ranges surrounding the basin folded and depressed the interior of the basin to form the extensive Maracaibo syncline. Because of the formation of the Maracaibo syncline, oil generation began in the central and southern parts of the synclinal basin and migrated northward. Hydrocarbons migrated up theflanks of the Maracaibo syncline along reactivated

ACKNOWLEDGEMENTS We thank Petroleos de Venezuela, S. A., for ´ providing seismic and well data used in this study. This work was supported by Grant 40499-AC8 from the Donors of the Petroleum Research Fund of the American Chemical Society to P. Mann. We thank S. Talukdar, D. Goddard, and R. Erlich for valuable reviews. The authors acknowledge...