Implementation of the Helgeson-Kirkham-Flowers Model to Study Reservoir Temperature Evolution during CO2 Injection Chris Binter M.S. Candidate Department of Geological Sciences San Diego State University Advisor Dr. Kathy Thorbjarnarson ABSTRACT A comprehensive one-dimensional numerical heat transfer module has been implemented into an existing reactive transport modeling application to study the temperature effects resulting from CO2-rich injection into sedimentary basins. The temperature module iteratively calculates thermophysical properties of charged aqueous solutes and uses these properties to compute a spatial and temporal temperature profile. An advection-diffusion model governing heat transport is solved using a finite volume method with solute specific partial molal enthalpy and partial molal heat capacity values obtained using the Helgeson-Kirkham-Flowers (HKF) model. The temperature module has been used to study the temperature effects resulting from injection of CO2-rich water into the Oligocene Frio formation along the Texas Gulf Coast, with simulation parameters similar to the Frio Test Pilot Experiment. Simulation results were compared to bottom hole temperature data obtained from an observation well 30 meters away from the injection well during the injection phase. Results show an increase in temperature caused by the arrival of the CO2-rich injectant that is in agreement with the well data. Results further show small variations in injection rate and pressure have little effect on the temperature increase; while changing total carbon concentration in the injectant water has a direct impact on temperature. The simulated temperature profile correlates with other simulation results that show an increase in temperature resulting from CO2 injection. Temperature signatures predicted by numerical simulation could be used to monitor the migration of CO2-rich plumes. This module can also be used to conduct what-if scenarios to determine the maximum amount of CO2 that can be sequestered in a formation without exceeding a critical reservoir temperature that could damage instruments and seals.