Numerical Simulation Research of Excavation Based Enhanced Geothermal System

Abstract Under the premise that the global fossil energy is decreasing, geothermal energy has entered the public view with its huge reserves. Geothermal energy can supply energy stably and uninterruptedly without being restricted by factors such as seasons climates, sunlight changes, and has broad development potential. This paper introduces a new deep geothermal development model—Excavation Based Enhanced Geothermal System (EGS-E). The innovative excavation based EGS-E scheme uses mining techniques to form deep underground access for creating artificial heat reservoir with multi-level fracture networks using excavation, blasting, and caving. The working water enters the heat exchange pool through the shaft for heat exchange. Different from the traditional geothermal model, this model can form an ultra-large volume, high permeability heat source and stable heat storage due to its special structure. In this study, a steady-state 3D model was established to study the heat exchange, temperature at the water outlet, and pressure distribution at the central section of the excavation based enhanced geothermal system (EGS-E). The results show that: when the inlet fluid velocity increases from static to 100m/s, the average outlet fluid temperature decreases from 473.15K to 360K. The heat production is better than that of EGS-D, and it is an ideal alternative to the existing EGS