Heat Extraction Characteristics of Medium to Deep Horizontally Connected Geothermal Wells
Efficient heat extraction technology of geothermal well is the key to efficient and sustainable development.A numer-ical simulation model for horizontally connected geothermal wells has been established.The outlet fluid temperature and heat transfer under continuous and intermittent heat exchange conditions were calculated.Effects of injection temperature,injection flow rate and horizontal section length on the heat transfer performance of the geothermal system and the temperature recovery ability of rock strata were analyzed.The results show that the water temperature at the outlet of the geothermal well decreases with the increasing of injection flow,but heat extraction capacity of the whole system increases.When the injection temperature is high,the outlet water temperature can be effectively increased,but the heat exchange capacity of the system decreases greatly.With the increasing of horizontal section length,the outlet water temperature and heat exchange capacity gradually increase,and the heat transfer performance of geothermal well improves.Rock temperature recovery ability increases with the increasing of injection flow rate and injection temperature.Taking into account factors such as drilling cost and pump power consumption,the heat transfer performance of geothermal well can be effectively improved by appropriately increasing the injection flow,lowering the injection temperature and increasing the horizontal section length.Although increasing the injection temperature can improve the temperature recovery ability of rock formation,it is not conducive to improving the system heat production efficiency.
medium to deep geothermal energyhorizontally connected geothermal wellheat transfer performanceheat ex-tractionground temperature recovery ability