基于CO2地质储存工程的CO2增强地热系统中CO2注入温度对热储层热提取率影响分析——基于鄂尔多斯CCS工程

 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。

The Impacts of Different CO2 Injection Temperatures on Heat Extraction Rate in CO2 Enhanced Geothermal System: Based on the CCS Demonstration Project in Erdos

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.