Fluid-CO2 Injection in a Hypersaline Volcanic Systems: A Reactive Transport and Experimental Evaluation with Application to the Tuzla Geothermal Field, Turkiye

Abstract

This study evaluates the CO2 sequestration capability of the Tuzla Geothermal Field (TGF) in northwest T & uuml;rkiye under reservoir conditions (200 degrees C and 4.4 MPa). While ongoing studies at TGF have investigated CO2 co-injection primarily for geothermal heat extraction, the present study focuses on the associated potential for long-term CO2 storage. To this end, CO2-brine-rock interactions were examined through batch reactor experiments and reaction path modeling using the PhreeqC geochemical tool. The experiments revealed complex dissolution/precipitation reactions that altered reservoir properties, with mineralogical analyses (XRD, XRF, SEM, and EDS) showing the formation of secondary phases such as calcite, kaolinite, and Ca-rich aluminosilicates. These results indicate that the Tuzla reservoir rocks provide sufficient divalent cations to support mineral trapping under reservoir conditions. Overall, our findings highlight that, in addition to its promise for heat extraction, CO2 co-injection at TGF offers an opportunity for permanent geological storage, thereby strengthening the dual benefits of this approach.