Petroleum Geology of the Central Part of the Eastern Venezuelan Basin

Two main petroleum provinces are described for the central part of the Eastern Venezuelan basin. These include the southern foreland platform near the Orinoco, with its heavy oil fields of the Faja Petrolifera, and in the north, the giant El Furrial and related traps in the frontal thrusts of the Serrania. To identify the petroleum systems and define attractive petroleum plays in this complex foreland fold and thrust belt system, an integrated geologic model of the area has been built using stratigraphic, structural, reservoir, and geochemical data. The major results of the study are as follows: (1) a reliable stratigraphic synthesis including updated ages; (2) a coherent structural interpretation in the thrusted zones validated by a balanced north-south cross section, with relevant new interpretations being the discovery of out-of-sequence thrusts (Pirital thrust) and the involvement of upper crust in the deformation; (3) the description of reservoir and hydrodynamic models that emphasize the importance of the major Las Piedras, Oficina, and Merecure reservoirs; and (4) characterization of three different source rocks of marine and continental origin in the Guayuta Group (two marine sources) and Carapita Formation (one continental source). To better understand the petroleum generation in this area--the maturation of potential source rocks, expulsion, and migration of the hydrocarbons--one- and two-dimensional numerical modeling has also been attempted in the platform area for times before and after thrusting. This method has given an estimate of 420-1350 billion bbl of generated oil, of which 6-15% have been recognized within the study area.