异质裂隙内超临界CO₂地热提取特性数值模拟研究

To enhance the heat extraction performance of geothernial systems, the influence of fracture heterogeneity on the heat extraction capacity of CO₂-based geothernial systems is investigated. By using numerical simulation methods, the seepage, heat transfer, and heal extraction effects of supercritical CO₂ in heterogeneous fractures within hot dry rock were examined. The mechanism of fracture conductivity tuning technology (FCTT) was explored, and changes in total heat extraction before and after tuning were compared. The simulation results show that the spatial correlation length of permeability significantly affects heat extraction efficiency by altering the seepage network structure. Larger correlation lengths (ϕ≽0. 50 m) lend lo form solidified flow channels, limiting the heat exchange area, whereas smaller correlation lengths (ϕ≼0.33 m) allow low-permeability clusters lo be uniformly dispersed, enhancing heat compensation and making the heat extraction process more uniform. The luning effect of FCTT exhibits spatial heterogeneity: in adveclion-dominated regions with large ϕ, long-range heterogeneity still leads to solidified flow channels, while systems with small ϕ maintain multi-branch flow patterns, alleviating regional heal exchange imbalances. The total heal extraction increases as the correlation length decreases. When ϕ is reduced from 1.00 m to 0.20 m. the total extraction increases by 7. 05%. FCTT luning demonstrates more significant improvements in fractures with uneven fracturing. Under large correlation length conditions (ϕ=1.00 m), the total heal extraction within 1.5 months increases by 10.66%. This study provides a theoretical basis for fracture design and heal extraction prediction in geothermal systems based on supercritical CO₂ as ihe working fluid.