Abstract: The performance and safety assessment of the coupled thermo-hydro-mechanical process in deep geo-energy engineering are challenging, because of the complex mechanical behavior of deep reservoir rocks and in-situ geological conditions, as well as the scale disparity between wells and reservoirs. To improve the computational efficiency without losing accuracy, a simplified one-dimensional well model considering heat convection and conduction along well axis and heat transfer between fluid and cap rocks in the radial direction is proposed and incorporated into the deep reservoir model. Two case studies of the city geothermal fields in Beijing and Shandong, China, are presented to demonstrate the reasonability and efficiency of the proposed reservoir modeling method. The evolutions of the temperature, flow velocity and deformation fields in deep reservoirs are also discussed.