Increasing number studies were conducted to explore the heat extraction performance of the enhanced geothermal system (EGS). However, most previous studies ignore the wellbore fluid flow and heat transfer effects and the variation of water thermophysical properties. It is difficult to accurately evaluate the influence of each engineering parameter on the heat extraction performance of the system. Hence, based on the fully coupled wellbore-reservoir model, this paper explores the influence of formation temperature and engineering parameters on the heat extraction performance of the system. The effects of fluid flow and heat transfer in the wellbore on the system heat extraction performance under different formation temperatures is compared and analyzed. The effect of the injection temperature and flow rate on the system heat extraction performance is studied. Results show that the effects of wellbore flow and heat transfer on the system heat extraction performance increase with the formation temperature. Increasing the injection temperature will decrease the system pressure difference, but it also reduces the thermal power of the system. Increasing the flow rate will increase the thermal power of the system, but it also increase the system pressure difference.
The middle and deep high-temperature geothermal resources in China are abundant. The Enhanced geothermal system (EGS) is an effective means to develop deep high-temperature geothermal resources (Xu et al., 2018). Water is the most common working fluid for the EGS due to its high heat capacity and thermal conductivity.
