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| Titel |
Estimation of reactive surface area using a combined method of laboratory
analyses and digital image processing |
| VerfasserIn |
Jin Ma, Xiang-Zhao Kong, Martin O. Saar |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250146003
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| Publikation (Nr.) |
 EGU/EGU2017-9990.pdf |
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| Zusammenfassung |
| Fluid-rock interactions play an important role in the engineering processes such as chemical
stimulation of enhanced geothermal systems and carbon capture, utilization, and storage.
However, these interactions highly depend on the accessible reactive surface area of the
minerals that are generally poorly constrained for natural geologic samples. In particular,
quantifying surface area of each reacting mineral within whole rock samples is challenging
due to the heterogeneous distribution of minerals and pore space. In this study, detailed
laboratory analyses were performed on sandstone samples from deep geothermal sites in
Lithuania. We measure specific surface area of whole rock samples using a gas adsorption
method (so-called B.E.T.) with N2 at a temperature of 77.3K. We also quantify their porosity
and pore size distribution by a Helium gas pycnometer and a Hg porosimetry, respectively.
Rock compositions are determined by a combination of X-ray fluorescence (XRF) and
quantitative scanning electron microscopy (SEM) - Energy-dispersive X-ray spectroscopy
(EDS), which are later geometrically mapped on images of two-dimensional SEM-
Backscattered electrons (BSE) with a resolution of 1.2 μm and three-dimensional
micro-CT with a resolution of 10.3 μm to produce a digital mineral map for further
constraining the accessibility of reactive minerals. Moreover, we attempt to link
the whole rock porosity, pore size distribution, and B.E.T. specific surface area
with the digital mineral maps. We anticipate these necessary analyses to provide
in-depth understanding of fluid sample chemistry from later hydrothermal reactive
flow-through experiments on whole rock samples at elevated pressure and temperature. |
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