We first present with great details a three-dimensional transient model of enhanced geothermal systems (EGS) heat extraction processes. This model takes the reservoir as an equivalent porous medium while considers the local thermal non-equilibrium between solid rock matrix and fluid flowing in the fractured rock mass. One other salient feature of this model is its capability of simulating the complete subsurface thermo-hydraulic process in EGS, not only the thermo-flow in the reservoir and well boreholes, but also the heat transport in rocks enclosing the reservoir. Simulation results unravel...