Comparative study on heat extraction performance of three enhanced geothermal systems  

作　　者：Xiaotian Wu Yingchun Li Chun'an Tang 

机构地区：[1]State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,Dalian,116024,China [2]Deep Underground Engineering Research Center,Dalian University of Technology,Dalian,116024,China

出　　处：《Rock Mechanics Bulletin》2023年第2期63-75,共13页岩石力学通报（英文）

摘　　要：Enhanced geothermal systems(EGSs)in this study are classified as fracturing-EGS(F-EGS),pipe-EGS(P-EGS)and excavation-EGS(E-EGS)according to reservoir stimulation strategies.However,the heat extraction performances of three EGSs employing different stimulation strategies are not fully understood.Here,we define the region where the pore pressure increment calculated by a hydraulic fracturing process is higher than rock tensile strength as the stimulation region for establishing a more accurate F-EGS model,and then compare three geothermal systems to select a appropriate reservoir stimulation strategy.We find that the F-EGS model assuming an entire stimulated region significantly exaggerates the heat extraction results.The optimal conditions for P-EGS are low injection rates and short operation times,which is suiTablefor seasonal heating or multi-energy co-generation projects including a thermal recovery phase.Theoretically,E-EGS has better geothermal extraction performance than F-EGS based on existing model assumptions,but its construction feasibility and economics need further exploration.H2O is more suiTableas a heat exchange fluid in E-EGS than supercritical CO_(2).This study provides a reference for geothermal mining simulation and reservoir stimulation strategy selection.

关 键 词：Fracturing-EGS Pipe-EGS Excavation-EGS Heat extraction 

分 类 号：TU433[建筑科学—岩土工程]