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New 2-D Regional Structural Model, Restoration and Geochemical Calibration of the Maturín Sub-Basin, Eastern Venezuelan

Gilberto Sánchez1, Anahy Finno1, Jay Namson2, Linda Montilla1, Lucila Hernández1, and Noelia Baptista1
1 PDVSA, División Oriente, Gerencia de Exploración, Venezuela, Puerto La Cruz, Venezuela
2 Davis & Namson Consulting Geologists, La Crescenta, CA

The Maturín sub-basin is the most prolific producing area of the Eastern Venezuela Basin. Mesozoic to Holocene evolution involves Jurassic rifting, Cretaceous to Paleocene passive margin formation, and mid-Cenozoic development of an oblique thrust belt and associated foreland basin. This complex setting is associated with several petroleum systems which yield rich hydrocarbon accumulations as well as providing a guide for future exploration.

An exploration campaign has been designed to integrate the available data and to test the prospectivity of the undrilled areas. A 59 km long regional balanced cross section was constructed using numerous wells, seismic data and surface geology. This cross section provides the basis for the stratigraphic framework, structural evolution and hydrocarbon system modeling.

Four structural domains have been identified. 1) In the north is the Pirital block, which is a fault-bend fold structure involving a thick lower Cretaceous section. Although the thrust has a long history its latest movement suggests out-of-sequence activation. 2) South of the Pirital block is an area of high structural relief created by the Orocual duplex, which has new subthrust opportunities. 3) The third domain is defined by a long detachment from which several imbrications and back thrusts branch defining important petroleum fields such as El Furrial and Jusepín. 4) Finally, the fourth domain is located at the frontal part of the thrust system and involves younger rocks and shallower detachments that contain turbiditic sediments which represent new important reservoirs.