Oil & Gas Science and Technology (Jan 2019)
Geochemical modeling of changes in caprock permeability caused by CO2–brine–rock interactions under the diffusion mechanism
Abstract
Geologic Carbon Sequestration (GCS) has been widely considered as a significant means for reducing CO2 emissions to address global climate change. The caprock sealing plays a key role in determining permanence and security of carbon dioxide (CO2) storage in geologic formations. This study presents geochemical modeling of CO2–brine–rock interactions in a deep saline aquifer in the Jianghan Basin, which is a potential target for CO2 injection and geological storage. A one-dimensional model was developed to investigate the changes in caprock permeability caused by CO2–brine–rock interactions under the diffusion mechanism. The results show that the dissolution of K-feldspar and albite plays a key role in the variation of caprock permeability, which makes permeability increased by 60% at the bottom of caprock. The caprock permeability is increased with temperature by enhancing the minerals dissolution of caprocks. In addition, the common-ion effect generated by the increased salinity inhibits the minerals dissolution in caprock.