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The AAPG/Datapages Combined Publications Database

AAPG Special Volumes

Abstract


 
Chapter from: M 63:  Unconformities and Porosity in Carbonate Strata 
Edited By
D.A. Budd, A.H. Saller, P.M. Harris

Authors
Neil F. Hurley, Haydn C. Tanner, and Carlos Barcat

Carbonate Reservoirs

Published 1995 as part of Memoir 63
Copyright © 1995 The American Association of Petroleum Geologists.  All Rights Reserved.
 
Chapter 8

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Unconformity-Related Porosity Development in the Quintuco Formation (Lower Cretaceous), Neuquén Basin, Argentina

Neil F. Hurley
Marathon Oil Company
Littleton, Colorado, U.S.A.
Haydn C. Tanner
Marathon Oil Company
London, U.K.
Carlos Barcat
Marathon Oil Company
Buenos Aires, Argentina


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ABSTRACT

Porous dolomites are present below a distinctive stratigraphic marker within the lower Quintuco Formation (Lower Cretaceous, Berriasian-lower Valanginian) in the eastern Neuquén basin, Argentina. Dolomitized packstones and wackestones with moldic and sucrosic porosity provide the main reservoir facies in Rio Neuquén field and perhaps other oil fields in the area.

Lower Quintuco carbonates are comprised of: (1) oolitic grainstones, (2) burrowed, dolomitized oolite-skeletal-peloid packstones/ wackestones, (3) dolomudstones and bedded anhydrites, and (4) very fine-grained, superficially coated oolite grainstones. These sediments are commonly packaged into shoaling- and coarsening-upward parasequences.

Reservoir-quality porosity and permeability exist almost exclusively in burrowed, dolomitized packstones and wackestones. These strata are interpreted as off-bar facies deposited on the landward side of bar complexes, similar to modern facies analogs known in the Joulters Cay area of the Bahamas. In the lower Quintuco Formation, dolomite preferentially replaced carbonate mud. Below an inferred widespread paleo-exposure surface, ooid-skeletal-peloid grains were then dissolved to leave an open pore network with abundant moldic and intercrystalline porosity.

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