Mineralogical and geochemical analysis of Fe-phases in drill-cores from the Triassic Stuttgart Formation at Ketzin CO₂ storage site before CO₂ arrival

Author(s)

Monika Kasina, Susanne Bock, Hilke Würdemann, Dieter Pudlo, Aude Picard, Anna Lichtschlag, Christian März, Laura Wagenknecht, Laura M. Wehrmann, Christoph Vogt, Patrick Meister

Abstract

Reactive iron (Fe) oxides and sheet silicate-bound Fe in reservoir rocks may affect the subsurface storage of CO2 through several processes by changing the capacity to buffer the acidification by CO2 and the permeability of the reservoir rock: (1) the reduction of three-valent Fe in anoxic environments can lead to an increase in pH, (2) under sulphidic conditions, Fe may drive sulphur cycling and lead to the formation of pyrite, and (3) the leaching of Fe from sheet silicates may affect silicate diagenesis. In order to evaluate the importance of Fe-reduction on the CO2 reservoir, we analysed the Fe geochemistry in drill-cores from the Triassic Stuttgart Formation (Schilfsandstein) recovered from the monitoring well at the CO2 test injection site near Ketzin, Germany. The reservoir rock is a porous, poorly to moderately cohesive fluvial sandstone containing up to 2–4 wt% reactive Fe. Based on a sequential extraction, most Fe falls into the dithionite-extractable Fe-fraction and Fe bound to sheet silicates, whereby some Fe in the dithionite-extractable Fe-fraction may have been leached from illite and smectite. Illite and smectite were detected in core samples by X-ray diffraction and confirmed as the main Fe-containing mineral phases by X-ray absorption spectroscopy. Chlorite is also present, but likely does not contribute much to the high amount of Fe in the silicate-bound fraction. The organic carbon content of the reservoir rock is extremely low (

Organisation(s)

Department of Geology

External organisation(s)

Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum, Jagiellonian University in Krakow, Friedrich-Schiller-Universität Jena, Hochschule Merseburg, Max-Planck-Institut für marine Mikrobiologie, Harvard University, University of Southampton, Newcastle University, State University of New York, Stony Brook, Jacobs Universität Bremen

Journal

Environmental Earth Sciences

Volume

76

No. of pages

20

ISSN

1866-6280

DOI

https://doi.org/10.1007/s12665-017-6460-9

Publication date

02-2017

Peer reviewed

Yes

Austrian Fields of Science 2012

105106 Geodynamics

Keywords

ASJC Scopus subject areas

Water Science and Technology, Earth-Surface Processes, Pollution, Geology, Soil Science, Global and Planetary Change, Environmental Chemistry

Portal url

https://ucrisportal.univie.ac.at/en/publications/0d4fe459-b16c-491d-bf79-8232f6c95054