Effects of heat transfer fluid and boundary conditions on temperature field of enhanced geothermal system

Enhanced geothermal system(EGS) is considered to be the most effective way to mine hot dry rock. A conceptual model of rock mass-fracture-rock mass was established to study the limitation of temperature, insulation and heat transfer on the temperature field of enhanced geothermal system and supercritical carbon dioxide enhanced geothermal system. The temperature field of the rock mass under three boundaries for 30 years has been obtained. Effects of fluid velocity, specific heat capacity and thermal conductivity of rock mass on the temperature field were studied. The results show that boundary conditions have a great influence on temperature change of the reservoir. Under three boundary conditions,flow velocity of the fluid has a great influence on the temperature. But thermal conductivity and specific heat capacity of the rock mass have a little influence on the temperature. Under the same boundary conditions, heat exchange effect of the supercritical carbon dioxide enhanced geothermal system is significantly better than that of the traditional enhanced geothermal system.