INTEGRATED PETROPHYSICAL AND SEDIMENTOLOGICAL CHARACTERIZATION OF CHLORITE-BEARING LATE DEVONIAN RESERVOIR SANDSTONES, CHACO BASIN, BOLIVIA

B. Valsardieu, S. Rousse, M. Blanco, J. Cordova, C. Calle, F. Schneider

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In many parts of the world (Bolivia, Algeria...), Devonian reservoir sandstones are known to contain chlorite-family minerals. Depending on their disposition (i.e., grain-coating and/or pore-filling) and quantity, this authigenic clay can enhance or degrade the petrophysical characteristics of these sandstones during diagenesis. In the “El Dorado” field (subandean Chaco Basin, Bolivia), the Devonian (Frasnian) “Guanacos” reservoir hosts abundant chloritic sandstones. These sandstones were deposited by shallow marine prograding shoreface system, fed by tide-dominated rivers, within a low subsidence cratonic basin setting. Among studied stratigraphic succession, 7 facies have been identified, using wireline logs cross-plots, where 4 distinctive sandstones facies are recognized by their mineralogical content, defining: “clean“, “chloritic“, “radioactive“and “dirty“facies. These 4 sandy electrofacies were later cross-compared thanks to thin-sections and porosity/permeability plugs results analysis. The “clean” sandstone facies exhibit chlorite-coated grains together with “open” porosity, that both retain good porosity and permeability ranges as the “coating” have prevented the secondary growth of quartz during burial diagenesis. In all other sandstone facies, variable chlorite content is present, occurring mostly as pore-filling authigenic clay cement. This chloritic cement is even more abundant as the grain-size decreases which implies a coeval degradation of permeability without particularly affecting porosity.

Original languageEnglish
Title of host publication83rd EAGE Conference and Exhibition 2022
PublisherEuropean Association of Geoscientists and Engineers, EAGE
Pages2249-2253
Number of pages5
ISBN (Electronic)9781713859314
StatePublished - 2022
Externally publishedYes
Event83rd EAGE Conference and Exhibition 2022 - Madrid, Virtual, Spain
Duration: 6 Jun 20229 Jun 2022

Publication series

Name83rd EAGE Conference and Exhibition 2022
Volume4

Conference

Conference83rd EAGE Conference and Exhibition 2022
Country/TerritorySpain
CityMadrid, Virtual
Period6/06/229/06/22

Bibliographical note

Publisher Copyright:
Copyright© (2022) by the European Association of Geoscientists & Engineers (EAGE). All rights reserved.

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