Experimental Study on the Interplay between Different Brine Types/Concentrations and CO 2 Injectivity for Effective CO 2 Storage in Deep Saline Aquifers

Salt precipitation during CO 2 storage in deep saline aquifers can have severe consequences on injectivity during carbon storage. Extensive studies have been carried out on CO 2 solubility with individual or mixed salt solutions; however, to the best of the authors’ knowledge, there is no substantial study to consider pressure decay rate as a function of CO 2 solubility in brine, and the range of brine concentration for effective CO 2 storage. This study presents an experimental core flooding of the Bentheimer sandstone sample under simulated reservoir conditions to examine the effect of four different types of brine at a various ranges of salt concentration (5 to 25 wt.%) on CO 2 storage. Results indicate that porosity and permeability reduction, as well as salt precipitation, is higher in divalent brines. It is also found that, at 10 to 20 wt.% brine concentrations in both monovalent and divalent brines, a substantial volume of CO 2 is sequestered, which indicates the optimum concentration ranges for storage purposes. Hence, the magnitude of CO 2 injectivity impairment depends on both the concentration and type of salt species. The findings from this study are directly relevant to CO 2 sequestration in deep saline aquifers as well as screening criteria for carbon storage with enhanced gas and oil recovery processes.