Pore-scale kinetics of calcium dissolution and secondary precipitation during geological carbon storage

Abstract

Geological carbon storage (GCS) in deep underground formations presents a significant opportunity to mitigate anthropogenic emissions of carbon dioxide in the context of climate change. The injected carbon dioxide may acidify the formation brine and dissolve carbonate minerals in the storage formations. Understanding the dynamics of carbonate dissolution at reservoir conditions is crucial for assessing the integrity and stability of reservoir rocks. Using carbonate-functionalized micromodels we investigate the pore-scale dynamics of carbonate dissolution and shed light on the interplay between surface reactions and mass transfer with relevance for geological carbon storage. Our experimental observations reveal the complex interplay between carbon dioxide exsolution/mineralization and mineral dissolution/precipitation during injection. Local chemical reactions and hydrodynamics impact the dissolution rate, whereas the presence of a free carbon dioxide phase can impede carbonate dissolution. Hence, we provide new experimental data that enhance our fundamental understanding of coupled geochemical GCS reactions that can augment the development of accurate and reliable constitutive models that assess leakage risks and the stability of mitigation techniques such as microbial-induced carbonate precipitation.