ABSTRACT The Maturin basin is a supercharged hydrocarbon setting that hosts the world’s largest individual oil accumulation: the Orinoco Belt, in situ 1.2 TBO. Miocene strata represent the most prolific reservoirs in the Maturin and in several of the Eastern Venezuela-Trinidad oil districts. Production in this region is in excess of 10 BBO. In spite of protracted and intense exploration and production activity by the oil industry, detailed stratigraphic knowledge on the oil-bearing Miocene successions has received only limited consideration in the public domain literature. As part of a field reactivation project undertaken on behalf of Corpoven S.A., rightholder of the Quiamare-La Ceiba unit ( Fig. 1 ), the Lower-Middle Miocene succession in NE Anzoátegui was analyzed from a sequence-stratigraphic and reservoir-characterization perspective. The study follows a four-fold approach: the first part outlines the geodynamic context and describes the key elements of the basin-scale Miocene stratigraphy and paleogeography; the second part discusses the sequence stratigraphy of the 4,000 m (12,000 ft) thick Miocene series over the SW fringe of the Maturin fold-thrust belt, as well as the implications of the regional stratal patterns and facies architecture for trapping potential; the third part examines the anatomy of individual reservoirs at the parasequence scale, describes the effects of fourth-order sequences on trapping, and analyzes internal reservoir facies heterogeneities; the last part focuses on the potential of seismic inversion for pre-drill reservoir prediction and efficient development planning. Figure 1. Location map of the area of this study and the Eastern Venezuela Basin.

The igneous and metamorphic rocks of Venezuela may be classified in three geographic units: a southern Precambrian Shield, an intermediate belt of Paleozoic age and a northern border of Mesozoic to Tertiary age. The shield is exposed in the south; it extends northward under a sedimentary cover to an inferred contact with the metamorphosed Paleozoic or Mesozoic-Tertiary rocks. South of this contact, in the eastern states of Anzoátegui and Monagas, the shield's oldest known sedimentary cover is of Cretaceous age; to the west, it is of Cambrian age. A graben is identified in the State of Guarico, located approximately along the contact of the Paleozoic basement with the Precambrian Shield. It contains a 2,390 m (7,840 ft) column of sedimentary rocks of Carboniferous and Jurassic age, not previously identified in the Barinas-Apure and Eastern Venezuela basins. Preliminary interpretation of recently acquired aeromagnetic data indicates that this feature forms part of a much longer graben, hitherto not known, which may extend westward from near Barcelona, Anzoátegui, to the Colombian border at approximately 70° 00' West Longitude, 7° 10' North Latitude, a distance of 600 km (375 mi).