| 张新立,袁益龙,汪禹,钟承昊,于涵,许天福.应力作用下不同粒径花岗岩粗糙裂隙渗透性演化规律研究[J].地质找矿论丛,2026,41(1):104-111,145 |
| 应力作用下不同粒径花岗岩粗糙裂隙渗透性演化规律研究 |
| Permeability Evolution of Rough Fractures in Granite with Different Grain Sizes under Stress |
| 投稿时间：2025-11-15 修订日期：2026-01-15 |
| DOI：10.6053/j.issn.1001-1412.2026.01.010 |
| 中文关键词: 增强型地热系统 岩心驱替实验 花岗岩粒径 裂隙渗透率 力学变形 |
| 英文关键词:enhanced geothermal systems core flooding experiment granite grain size fracture permeability mechanical deformation |
| 基金项目:国家自然科学基金项目“深部超临界地热条件岩石变形规律及其对水热运移影响机制研究”（No.42372283）。 |
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| 中文摘要: |
| 干热岩储层主要岩性为花岗岩，不同区域、不同埋深储层花岗岩的粒径存在一定差异。然而，应力作用下裂隙花岗岩渗透性的粒径效应尚不清楚。为此，本研究利用岩心驱替实验系统，开展了应力加卸载条件下不同粒径花岗岩裂隙岩心渗透性测试。结果表明，裂隙渗透率与围压呈幂函数负相关关系，加载阶段细粒、中细粒、中粒和粗粒花岗岩裂隙渗透率分别衰减了93.45%、94.38%、96.35%和96.64%，卸载阶段裂隙渗透率分别恢复了12.45%、10.06%、7.87%和5.70%。表明加卸载过程裂隙面在应力作用下了发生塑性变形，导致裂隙渗透率出现不可逆衰减，该现象在粗粒花岗岩中最为明显。基于实验数据，本文建立了不同粒径花岗岩裂隙渗透率与有效应力的幂函数关系，揭示了花岗岩裂隙渗透率应力敏感性随粒径增大而增强的规律，高围压下该粒径效应逐渐弱化，研究成果可为干热岩储层优选与不同粒径花岗岩裂隙长期稳定方案设计提供了科学依据。 |
| 英文摘要: |
| The dominant lithology of Hot Dry Rock (HDR) reservoirs is granite. Granite across different regions and burial depths exhibits differences in grain size. However, the effect of grain size on permeability in stressed fractured granite remains unclear. To fill this gap, a series of fracture permeability tests was performed on the fractured granite cores with different grain sizes under loading-unloading processes, using a core flooding experimental system. The results show that the fracture permeability exhibits a negative power-law relationship with confining pressure. During the loading, the fracture permeability of fine-grained, medium-fine-grained, medium-grained, and coarse-grained granite decreased by 93.45 %, 94.38 %, 96.35 %, and 96.64 %, respectively. During the unloading, the fracture permeability recovered by only 12.45 %, 10.06 %, 7.87 %, and 5.70 %, respectively. This indicates that during the loading-unloading process, plastic deformation occurred on the fracture surfaces under stress, resulting in an irreversible reduction in fracture permeability. This phenomenon is most pronounced in coarse-grained granite. Based on experimental data, a power-law relationship between fracture permeability and effective stress was established for granite samples of different grain sizes. The results indicated that the stress sensitivity of granite fracture permeability increases with increasing grain size, and this effect gradually diminishes under high confining pressure. The findings of this work provide a scientific basis for the selection of HDR reservoirs and the design of long-term fracture-stability schemes for granite with different grain sizes. |
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