CO₂ fracturing can perform better in enhancing the unconventional gas production than water-based fracturing by avoiding serious reservoir permeability damage. The evolution of the fracture permeability of created and natural fractures during exposure to different fracturing fluids is critical to the effectiveness of CO₂ fracturing. Therefore, a comprehensive steady-state permeability tests by using various fracturing fluids in fractured siltstone under tri-axial conditions was conducted. According to the experimental results, the decrease of the uniaxial compressive strength of tested samples after water saturation was greater than 23% due to the increase of pore pressure. The flow capacity of the fracture system can suffer a great loss by the irreversible deformation of fracture surfaces caused by the high confinements and water softening effects. The water–rock reactions can accelerate the reductions of fracture hydraulic aperture at confining pressures higher than 20 MPa. The fracture gas conductivity decreased by 80–90% at fully or partially water-saturated rock formations due to the water softening and capillary effects.

中文翻译：

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不同储层和注入条件下粉砂岩裂隙气体流特征的实验评价：在CO 2基压裂中的应用

通过避免严重的储层渗透率破坏，CO ₂压裂可以比非水基压裂更好地提高非常规天然气的产量。暴露在不同压裂液中的天然裂缝和天然裂缝的渗透率演变对CO ₂的有效性至关重要压裂。因此，在三轴条件下，在裂隙粉砂岩中使用各种压裂液进行了综合稳态渗透率测试。根据实验结果，由于孔隙压力的增加，水饱和后测试样品的单轴抗压强度降低幅度大于23％。由于高密闭度和水软化作用引起的裂缝表面不可逆的变形，裂缝系统的流量会遭受很大的损失。在高于20 MPa的围压下，水岩反应可以加速裂缝水力孔的减小。由于水软化和毛细作用，在完全或部分水饱和的岩层中，压裂气导率降低了80–90％。