This study presents a process to find the maximum heat extraction in supercritical CO2 geothermal system. Little attention in the previous studies about the thermal dispersion receives. A porous heat transfer model and the corresponding porous experimental system are proposed to build the correlation of thermal dispersion. The correlation of thermal dispersion is obtained from the fitting process between the corresponding model and experiment. The maximum geothermal extraction is found based on the optimal process and porous heat transfer model considered thermal dispersion. The optimal operated pressure and mass flow rate based on supercritical CO2 flow are obtained. These results will result in the range of the realistic operation and reduce the cost of process in in-situ. (C) 2019 Elsevier Ltd. All rights reserved.