CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING



AbstractA 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.



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