The Coupled Effect of Fines Mobilization and Salt Precipitation on CO 2 Injectivity

In terms of storage capacity and containment efficiency, deep saline aquifers are among the best candidates for CO 2 storage. However, salt precipitation in the wellbore vicinity and fines mobilization ensued from in situ mineral dissolution could impair CO 2 injectivity and reduce the quality and capacity of deep saline reservoirs for CO 2 storage. The mechanisms of salt precipitation and its impact on CO 2 injectivity have been studied, but the effects of fines mobilization have not been properly investigated. We conducted core-flood experiments and theoretical studies to investigate the impact of fines mobilization on CO 2 injectivity, the relative contribution of fines mobilization and salt precipitation to injectivity impairment, and the coupled effect of salt precipitation and fines mobilization. We found that, mineral dissolution and transport effects could induce up to about 26% injectivity impairment. The findings also suggest that about 0.3 wt % particle concentration in the pore fluid could induce over twofold injectivity impairment compared to about 10 wt % of total dissolved salt in the formation water. Salt precipitation was also found to compound injectivity impairment induced by fines mobilization. The present study provides important insight, and could serve as a foundation to inspire further experimental and theoretical investigation into the effects of mineral dissolution and fines mobilization in the context of CO 2 injectivity.