以鄂尔多斯CO2地质储存工程区马家沟组地层为人工地热储层,用TOUGH2软件建立以CO2为传热载体的CO2-EGS模拟模型,设计并模拟了5种不同的CO2注入温度(18~42℃)条件下CO2-EGS系统运行特征,分析了CO2注入温度对热提取率和系统可持续性的影响。结果表明,5种方案的热量提取率在CO2-水驱替阶段变化区间为6.37~7.9MW,在液相流消失阶段变化区间为6.64~8.68MW。整个CO2-EGS系统运行期的平均地层热提取率为6.56~8.47MW,系统可持续时间10.58~11.49a,系统运行期温度下降速率为1.89~1.74℃/a。CO2的注入温度对深层地热能系统热量提取率影响显著,对系统的可持续性影响较小。为了获得最大的经济效益,应在CO2-EGS运行允许范围内减小CO2的注入温度。研究成果可以为CO2地质储存与资源化利用提供参考。
Majiagou geologic formation in Erdos Carbon Capture and Storage (CCS) demonstration project is chosen as artificial geothermal reservoir, the simulation software of TOUGH2 is used to create numerical models of Enhanced Geothermal System (EGS) in which CO2 is heat transfer carrier. In order to analyze the impact of CO2 injection temperatures on heat extraction rate and the sustainability of CO2-EGS, five cases with different CO2 injection temperatures ranged from 18℃ to 42℃ are designed. Simulation results show that the range of the average heat extraction rate for those five cases is 6.56~8.47MW in the entire period of CO2-EGS operation. The heat extraction rates vary over time and the rate is 6.37~7.9MW in the stage of CO2 and water displacement and the rate is 6.64~8.68MW after aqueous phase disappear, respectively. In whole process of CO2-EGS, the temperature of production fluid decreases with a rate of 1.89~1.74℃/a and the system sustainable time is 10.58~11.49a. Injection temperature of CO2 significantly impacts the heat extraction rate of EGS; however has a little impact on the sustainability of CO2-EGS. Reducing CO2 injection temperature in the range permitted by the CO2-EGS operation is a good choice for CO2-EGS. Those results could provide the reference for the geological storage and resource utilization of CO2.