Geothermal exploitation and electricity generation from multibranch U-shaped well–enhanced geothermal system

Abstract

A novel method for geothermal exploitation and electricity generation from multibranch U-shaped well–enhanced geothermal systems is proposed herein. Furthermore, a coupled wellbore-formation transient heat transfer model is presented to describe the dynamic changes in temperature of fluids and geothermal formation. Moreover, heat recovery rate, power generation rate, and economic feasibility, as well as their influencing factors under this new method was assessed via numerical simulations. Simulation results indicate that in the initial stage of exploitation, both the fluids temperature in the horizontal wellbore and geothermal formation near the well decrease rapidly with time, and the wellbore temperature decreases at a lower rate until a quasi-equilibrium state is attained. The heat mining efficiency and power generation rate of multibranch U-shaped wells are significantly better than those of a single branch U-shaped well, and the levelized cost of energy can be reduced by 0.1034 $/kWh. Sensitivity studies indicate that the levelized cost of energy reaches the minimum at a water injection rate of 900 m3/d and a horizontal wellbore length of 5000 m. Finally, an economic plate was used to design the well structure and injection parameters for geothermal exploitation, as well as make for a detailed economic evaluation of geothermal resources.