Geologic carbon sequestration is the injection of CO2 into deep sedimentary formations for permanent isolation from the atmosphere and mitigation of climate impacts. Storage permanence requires containment beneath impermeable caprocks, but reactions between carbonic acid and caprock minerals may increase the permeability of caprock breaches. Our research seeks to understand the geochemical and mineralogical conditions that control CO2 leakage. Our work combines high-pressure core flow experiments, x-ray imaging methods, reactive transport modeling, and computational fluid dynamics simulations. We have found that fracture permeability can increase substantially as a result of calcite dissolution, and this could lead to unintended leakage. However, the extent of permeability increase is affected by newly-created surface roughness, mobilization of fines, and creation of wormhole channels. It remains an ongoing research priority to develop computationally-tractable reactive transport models that accurately account for these complex processes of reaction-induced permeability evolution.

Geochemistry challenges in reliable geologic carbon sequestration

248th National Meeting (2014)

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