共和盆地增强型地热系统开采过程数值模拟

Numerical simulation of hot dry rock exploitation using enhanced geothermal systems in Gonghe Basin

干热岩资源是未来重要的清洁型能源,增强型地热系统(EGS)能够实现干热岩资源的开发利用。青海共和盆地干热岩资源储量巨大,可以作为EGS系统的靶区之一。水在热储层中的运移包含复杂的水-热耦合过程,不同的EGS运行方案对电厂发电能力有重要影响。本文基于共和盆地深部地质条件,建立了表征EGS系统水热特征的数值模型,研究了温度场、压力场的时空分布特征,并分析注入流体温度和循环流速两个可控因素对提热过程的影响。结果表明:在设计的运行方案(循环流速20 kg/s;注入温度60℃)下,最大提热速率可达11 MW,储层寿命为22年。注入温度每降低10℃,系统最大提热速率约增加10%,且对储层寿命没有明显影响;增加循环流速可以得到更大的热提取速率,但会减少储层寿命。

Hot dry rock, which will become one of the most important resources in the future, can be developed and utilized using enhanced geothermal systems（EGSs）. Hot dry rock resources are abundant in Gonghe basin, Qinghai province. Complex waterthermal coupling processes occur during water flow in the reservoir, and the power generation capacity of power plants is dependent on the EGS operation scheme. Based on the deep geological conditions of Qiabuqia in Gonghe basin, we established a numerical model to characterize the hydrothermal features of EGS, researched the temporal and spatial distribution of the temperature field and pressure field, and analyzed the influence of injection temperature and flow rate on heat extraction rate. The results show that the maximum heat extraction rate reached 11 Mw under the base scheme（20kg/s, 60 o C）, and the reservoir life was 22 years. The heat extraction rate will increase by about 10% with 10 o C increase of injection temperature, while the reservoir life remains the same.Increased flow rate will lead to a greater rate of heat extraction but shorter reservoir life.