posted on 2024-02-02, 04:29authored byAnil K. Battu, Quin R.S. Miller, Ruoshi Cao, Antoinette T. Owen, H. Todd Schaef
Basalt formations are promising candidates for the geologic
storage of anthropogenic CO2 due to their storage capacity,
porosity, permeability, and reactive geochemical trapping ability.
The Wallula Basalt Carbon Storage Pilot Project demonstrated that
supercritical CO2 injected into >800 m deep Columbia
River Basalt Group stacked reservoir flow tops mineralizes to ankerite-siderite-aragonite
on month-year time scales, with 60% of the 977 metric tons of CO2 converted within 2 years. The potential impacts of mineral
precipitation and consequent changes in the rock porosity, pore structure,
pore size, and pore size distributions have likely been underestimated
hitherto. Herein, we address these knowledge gaps using X-ray microcomputed
tomography (XMT) to evaluate the pore network architecture of sidewall
cores recovered 2 years after CO2 injection. In this study,
we performed a detailed quantitative analysis of the CO2-reacted basalt cores by XMT imaging. Reconstructed 3D images were
analyzed to determine the distribution and volumetric details of porosity
and anthropogenic carbonate nodules in the cores. Additional mineralogic
quantification provided insight into the overall paragenesis and carbonate
growth mechanisms, including mineralogic/chemical zonation. These
findings are being used to parametrize multiphase reactive transport
models to predict the fate and transport of subsurface CO2, enabling scale-up to commercial-scale geologic carbon storage in
basalts and other reactive mafic-ultramafic formations.