Study on Long-Term Heat Recovery Performance of Geothermal System in Closed/Abandoned Mines Based on RSM-BBD Method
The closed/abandoned mine contains rich potential resources,and the impact on the local economy and environment can be effectively reduced by innovatively developing its deep geothermal energy.In order to study the influence of the operation and structural parameters of the closed/abandoned mine geothermal system on its long-term heat recovery performance,the temperature-seepage multi-field coupling model of heterogeneous thermal reservoir in goaf was established,and the numerical experiment was carried out by combining RSM-BBD method.The temperature evolution law of reservoir during long-term heat recovery was studied,and the influence of single factors such as injection temperature,injection-production pressure difference,injection-production well length and the interaction between various factors on long-term heat recovery performance was analyzed.The results show that the cold front is first formed near the injection well,and with the increase of production time,it continues to expand near the heat recovery well.The non-uniform distribution of porosity in the thermal reservoir cause the cold front in the lower part of the thermal reservoir to reach the heat extraction well earlier.The R2 of the response surface model between each influencing factor and outlet temperature,total amount of heat extraction is greater than 0.9,and the P is less than 0.000 1,which can accurately predict the long-term performance of the heat extraction system.The results of factor sensitivity analysis show that the most influential factor on the total amount of heat recovery is injection-production well length,and the most influential factor on the outlet temperature is injection temperature.Through the preliminary exploration and research on the geothermal development of closed/abandoned mines,it is expected to provide reference for the rational utilization of such mines and the development of environmentally friendly energy.
Closed/abandoned mineGeothermal miningResponse surface methodThermal performanceTotal amount of heat extractionOutlet temperature