Liang Qinming, Huang Gun, Huang Jinyong, Zheng Jie, Wang Yueshun, Cheng Qiang
School of Resources and Safety Engineering, Chongqing University, Chongqing 400044, China.
School of Geology and Mining Engineering, Xinjiang University, Urumqi 830046, China.
Materials (Basel). 2024 Sep 15;17(18):4539. doi: 10.3390/ma17184539.
The exploration of Hot Dry Rock (HDR) geothermal energy is essential to fulfill the energy demands of the increasing population. Investigating the physical and mechanical properties of heated rock under different cooling methods has significant implications for the exploitation of HDR. In this study, ultrasonic testing, uniaxial strength compression experiments, Brazilian splitting tests, nuclear magnetic resonance (NMR), and scanning electron microscope (SEM) were conducted on heated granite after different cooling methods, including cooling in air, cooling in water, cooling in liquid nitrogen, and cycle cooling in liquid nitrogen. The results demonstrated that the density, -wave velocity (), uniaxial compressive strength (UCS), tensile strength (), and elastic modulus () of heated granite tend to decrease as the cooling rate increases. Notably, heated granite subjected to cyclic liquid nitrogen cooling exhibits a more pronounced decline in physical and mechanical properties and a higher degree of damage. Furthermore, the cooling treatments also lead to an increase in rock pore size and porosity. At a faster cooling rate, the fracture surfaces of the granite transition from smooth to rough, suggesting enhanced fracture propagation and complexity. These findings provide critical theoretical insights into optimizing stimulation performance strategies for HDR exploitation.
干热岩（HDR）地热能的勘探对于满足不断增长的人口的能源需求至关重要。研究不同冷却方法下加热岩石的物理和力学性能对干热岩的开发具有重要意义。在本研究中，对经过不同冷却方法（包括在空气中冷却、在水中冷却、在液氮中冷却以及在液氮中循环冷却）的加热花岗岩进行了超声测试、单轴强度压缩试验、巴西劈裂试验、核磁共振（NMR）和扫描电子显微镜（SEM）分析。结果表明，加热花岗岩的密度、纵波速度（）、单轴抗压强度（UCS）、抗拉强度（）和弹性模量（）随着冷却速率的增加而趋于降低。值得注意的是，经过液氮循环冷却的加热花岗岩在物理和力学性能方面表现出更明显的下降以及更高程度的损伤。此外，冷却处理还导致岩石孔隙尺寸和孔隙率增加。在较快的冷却速率下，花岗岩的断裂面从光滑转变为粗糙，表明断裂扩展增强且复杂性增加。这些发现为优化干热岩开发的增产措施策略提供了关键的理论见解。
