Time-Lapse Imaging of Reactive Mixing Inducing Carbonate Mineralization
in Basalt Cores
- Paiman Shafabakhsh,
- Benoit Cordonnier,
- Tanguy Le Borgne,
- Joachim Mathiesen,
- Gaute Linga,
- Anne Pluymakers,
- Anders Kaestner,
- Alessandro Tengattini,
- François Renard
Tanguy Le Borgne
Universite de Rennes - Campus Sante de Villejean
Author ProfileJoachim Mathiesen
Niels Bohr Institute, University of Copenhagen
Author ProfileAbstract
Mineral precipitation in geological formations occurs when reactive
fluids of varying compositions mix, altering the porous microstructure
of the rock. Basalt rocks are of particular interest for long-term CO2
storage due to their potential to rapidly mineralize CO2 into stable
carbonate minerals. We investigated reactive fluid mixing and subsequent
carbonate mineralization in porous basalt using time-lapse
three-dimensional neutron and X-ray imaging. Two flow-through
experiments with different injection rates were performed on basalt
cores, where co-injected CaCl2 and Na2CO3 solutions were mixed within
the porous network, leading to calcium carbonate precipitation.
Time-lapse neutron imaging distinguished the two injected fluids and
tracked their mixing. X-ray imaging was used to separate the solid
matrix from the pore space to enable fluid analysis in the neutron
images. A first experiment with a high flow rate induced a steady
transverse mixing pattern, captured by a decay of the concentration
variance through the sample, as measured by neutron imaging. A second
experiment at a lower flow rate promoted more temporal fluctuations in
the fluid distribution due to the multiphase flow of water and air in
the rock. The analysis of neutron images showed a significant mixing of
reactive fluids driven by these temporal fluctuations. Furthermore, a
higher-resolution, synchrotron X-ray image of one of the sample rocks
acquired after the experiment showed the formation of additional calcite
resulting from long-term diffusive mixing. The results highlight the
great potential and challenges of neutron and X-ray imaging in
characterizing pore-scale mixing and precipitation in rocks.03 Nov 2024Submitted to ESS Open Archive 04 Nov 2024Published in ESS Open Archive