Quantifying CO2 Trapping Mechanisms and Capacity in Open Saline Aquifers - The Role of Reservoir Heterogeneity

QUANTIFYING C02 TRAPPING MECHANISMS AND CAPACITY IN OPEN SALINE AQUIFERS - THE ROLE OF RESERVOIR HETEROGENEITY
Kuncho Kurtev, Achyut Mishra, Ralf R. Haese, Stephan K. Matthai

Injection of CO2 in open reservoirs will greatly enhance storage opportunities, but requires capillary, dissolution and mineral trapping to act rapidly and on short time and length scales. The proposed research project will test the hypothesis that CO2 migrating significant distances through ‘open’ saline aquifers will be trapped by capillary, dissolution and mineral precipitation mechanisms. In particular it will quantify how natural heterogeneity in saline aquifers enhances the trapping mechanisms, providing robust estimates of trapping rates in open and confined aquifers benchmarked against existing field data.

Transport, geochemical processes and the associated CO2 trapping mechanisms in geological reservoirs are highly dependent on the nature of structural and lithological heterogeneities. However, important cm- to meter scale heterogeneities are not incorporated into storage complex models because they can neither be seismically imaged nor represented by grid cells. This project will determine capillary, dissolution and mineral trapping over time for open and closed saline aquifers accounting for such heterogeneities. A series of coordinated process studies using experimental, analytical and numeric approaches will be carried out with the aim to estimate the proportion of CO2 trapping by the different mechanisms over time. The C02CRC Otway and the SaskPower Aquistore sites will be used as case studies, where detailed geological information is available. Ultimately, the project will advance the conceptual representation of CO2 trapping over time in saline aquifers to a quantitative representation based on our case studies.