Numerical modeling of the CO2 injection in the Kızıldere geothermal field using multiple inter-well tracer tests.

• We have developed a 3D sector model to predict the CO 2 storage capacity of the Kızıldere geothermal field. • The developed model is calibrated using static pressure and temperature measurements, chloride concentrations, and two inter-well tracer tests. • It has been predicted that 78–79 % of the injected CO 2 circulates in the reservoir. • It is possible to store 200,000 tons of CO 2 in the Kızıldere reservoir if the CO 2 is re-injected from multiple injection wells. Many geothermal power plants in Turkey emit high amounts of non-condensable gas (NCG), consisting mainly of CO 2. Thus, it is crucial to mitigate the NCG emissions by re-injecting the captured gas back into the reservoir. In this study, a numerical sector reservoir model is developed to inspect how the reinjected NCG dissipates in the reservoir for successful sequestration. To accurately characterize the flow characteristics in the reservoir, chloride concentrations observed at the production wells were matched. Furthermore, two multi-well slug tracer tests (one with NCG injection well and one from the northernmost shallow injection well by using different naphthalene-sulphonates) results have been used to calibrate the numerical model. Consequently, a high degree of quantitative and qualitative characterization of the reservoir section near the injection site has been achieved. Using the calibrated model, the impact of CO 2 -brine injection has been studied for different injection scenarios with varying injection rates and durations. The results of the CO 2 -charged brine injection showed that approximately 20 % of the injected CO 2 circulates in the reservoir, ensuring reduced CO 2 emissions. It has been estimated that 200 Mt of CO 2 emission can be safely removed if all injection wells are used for NCG re-injection. [ABSTRACT FROM AUTHOR]