Geothermal Energy Exploitation and Power Generation via a Single Vertical Well Combined with Hydraulic Fracturing

Abstract

A method of single vertical well combined with hydraulic fracturing is proposed to prevent short circuits and enhance heat mining. The technical and economic feasibilities of geothermal energy exploitation from a deep reservoir are analyzed based on this method. A simulation model was established to analyze the coupled heat transfer between wellbore and reservoir, and then thermodynamic performances and economic analyses of single-flash, double-flash, and flash–organic Rankine cycle geothermal power generation systems were carried out. Simulation results indicate that the heat mining rate can maintain above 3 MW after 40 years of exploitation from the reservoir with 235°C using a water circulation rate of 432 m3/day. A combination of large horizontal permeability, high circulation flow rate, and excellent thermal-insulating tubings favors high heat mining. Thermodynamic cycle analyses show that the net power outputs from the single-flash, double-flash, and flash–organic Rankine cycle systems under the optimal condition are 513, 646, and 627.8 kW, respectively. Correspondingly, the geothermal power generation cost ranges from $0.086/kWh to $0.095/kWh, which is a little higher than the conventional power generation cost. Double-flash or flash–organic Rankine cycle is suggested to be installed for geothermal power generation if more electricity is needed.