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| Titel |
On the complex conductivity signatures of calcite precipitation |
| VerfasserIn |
Philippe Leroy, Shuai Li, Damien Jougnot, André Revil, Yuxin Wu |
| 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 |
250149231
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| Publikation (Nr.) |
 EGU/EGU2017-13564.pdf |
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| Zusammenfassung |
| When pH and alkalinity increase, calcite frequently precipitates and hence modifies the
petrophysical properties of porous media. The complex conductivity method can be
used to directly monitor calcite precipitation in porous media because it is sensitive
to the evolution of the mineralogy, pore structure and its connectivity. We have
developed a mechanistic grain polarization model considering the electrochemical
polarization of the Stern and diffuse layer surrounding calcite particles. Our complex
conductivity model depends on the surface charge density of the Stern layer and
on the electrical potential at the onset of the diffuse layer, which are computed
using a basic Stern model of the calcite/water interface. The complex conductivity
measurements on a column packed with glass beads where calcite precipitation occurs are
reproduced by our surface complexation and complex conductivity models. The
evolution of the size and shape of calcite particles during the calcite precipitation
experiment is estimated by our complex conductivity model. At the early stage of the
calcite precipitation experiment, modeled particles sizes increase and calcite particles
flatten with time because calcite crystals nucleate at the surface of glass beads and
grow into larger calcite grains around glass beads. At the later stage of the calcite
precipitation experiment, modeled sizes and cementation exponents of calcite particles
decrease with time because large calcite grains aggregate over multiple glass beads, a
percolation threshold is achieved, and small and discrete calcite crystals polarize. |
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