The properties of geothermal working fluids have great influence on the heat extraction performance of an enhanced geothermal system (EGS). In addition to H₂O, N₂O and CO₂ have also been proposed as geothermal working fluids. In order to analyze and compare the heat extraction performances of the N₂O, CO₂ and H₂O EGS, a two-dimensional thermo-hydraulic-mechanical (THM) coupled EGS model with discrete fractures is established. In addition, the influences of injection-production parameters on the heat extraction effects of EGS with different working fluids are also analyzed. The results indicate that the heat extraction performances of N₂O-EGS and CO₂-EGS are almost the same under the same conditions. Taking into account the stable production time and the stability of supporting equipment, the performances of N₂O-EGS and CO₂-EGS are better than H₂O-EGS. Furthermore, a lower injection temperature is conducive to the heat extractions of N₂O-EGS and CO₂-EGS, while the injection mass flow rate and production pressure should be designed reasonably according to the actual situation. As for H₂O-EGS, a higher production pressure is conducive to its performance, while its injection temperature and injection mass flow rate should be designed reasonably.

地热工作液的性质对增强型地热系统（EGS）的热提取性能有很大影响。除了H ₂ O，N ₂ O 和CO ₂也被提议作为地热工作流体。为了分析和比较N ₂ O、CO ₂和H ₂ O EGS 的抽热性能，建立了具有离散裂缝的二维热-水力-机械(THM) 耦合EGS 模型。此外，还分析了注采参数对不同工质下EGS的排热效果的影响。结果表明，N ₂ O-EGS 和 CO的吸热性能₂ -EGS 在相同条件下几乎相同。考虑到稳定的生产时间和配套设备的稳定性，N ₂ O-EGS和CO ₂ -EGS的性能优于H ₂ O-EGS。此外，较低的注入温度有利于N ₂ O-EGS和CO ₂ -EGS的热提取，同时应根据实际情况合理设计注入质量流量和生产压力。对于H ₂ O-EGS，较高的生产压力有利于其性能，同时应合理设计其注入温度和注入质量流量。