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Thermophysical properties of heat transfer fluid may experience significant changes during heat extraction process in enhanced geothermal system (EGS). The present work extends a previous EGS model by implementing pressure- and temperature-dependent thermophysical properties of real water and super-critical carbon dioxide (SCCO₂), and employed the new model to simulate the long-term heat extraction processes of water-EGS and SCCO₂-EGS. Comparison between the model results finds at a given fluid injection pressure, the lifetime of water-EGS is longer than that of SCCO₂-EGS while the heat extraction rate of the latter is higher than the former, leading to approximately the same cumulative heat extraction amount at the end of EGS operation. Relative to water, larger density-temperature dependence of SCCO₂ leads to stronger natural convection of fluid flow in EGS reservoir and makes the heat …