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Pérez, Jorge1 
(1) Universidad de Oriente, UDO, Ciudad Bolívar, Venezuela

ABSTRACT: Paleogeography of the Lower to Middle Miocene, T to M3/M4 Sandstones(Oficina Formation), Chimire-Boca Oildfield, Anzoátegui State, Eastern Venezuela

The Chimire-Boca oilfield is located in the eastern Venezuela basin (Anzoátegui State). The Oficina Formation, from the Lower to Middle Miocene, is the main reservoir rock in this area. 
Sedimentologic and stratigraphic analysis of 1500 feet of cores, distributed in four wells, well logs, petrophysical and petrographycal data and biostratigraphic analysis, allowed the interpretation of the depositional environment as a fluvial dominated deltaic system, and permitted to construct paleogeographic and physical quality rock maps (total thickness, net gross, isoporosity and isopermeability) of the most important oil reservoir intervals. 
Petrographycal analysis of 25 thin sections, permitted to classify the reservoir sandstones into: quartzose and sublitharenite/litharenite; where, quartz overgrowth cement prevails. 
Stratigraphycal analysis reveals an overall transgressive sequence, and the vertical paleogeographic evolution evidences a drainage pattern in a northeast direction, with sporadic changes to the north.


AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.