Using supercritical CO₂ as fracturing medium to develop shale gas not only improve the stimulation effect of reservoir, but also reduce CO₂ emissions. To optimise the flow of shale gas into a wellbore, it is important to understand the flow characteristics of gas in the shale fracture system after reservoir reconstruction. To date, no research has been conducted on the effect of supercritical CO₂ on the flow characteristics of gas in shale fractures. Hence, in this study, experiments were conducted to investigate the effect of supercritical CO₂ on the conductivity of shale fractures, for different effective stress and gas pressure conditions. Also, the changes in shale fracture surface roughness, hydraulic aperture, Reynolds number, and friction factor, before and after soaking with supercritical CO₂ have been studied; the results show an increase in shale fracture conductivity for low effective stress conditions, and a decrease in conductivity for high effective stress conditions. Further, the relationship between the hydraulic aperture of shale fractures and the effective stress is found to be hyperbolic. The changes in the conductivity of shale fractures due to the influence of supercritical CO₂ are primarily because of an increase in shale fracture surface roughness and a decrease in the resistance to deformation of the fractures. Nonlinear gas flow behaviour in shale fractures has been observed, which can be described by the Forchheimer equation. A new friction factor model based on Reynolds number and relative roughness is proposed, that can more accurately reflect the flow pattern of gas in shale fractures than the classical Lomize model.

以超临界CO ₂为压裂介质开发页岩气，不仅提高了储层的增产效果，而且减少了CO _2的排放。为了优化进入井眼的页岩气流量，重要的是要了解储层改造后页岩压裂系统中气体的流动特征。迄今为止，还没有关于超临界CO ₂对页岩裂缝中气体流动特性影响的研究。因此，在这项研究中，进行了实验以研究超临界CO ₂的作用。在不同有效应力和气压条件下页岩裂缝的电导率 此外，研究了超临界CO ₂浸泡前后的页岩裂缝表面粗糙度，水力孔径，雷诺数和摩擦系数的变化。结果表明，在低有效应力条件下页岩裂缝电导率增加，在高有效应力条件下页岩裂缝电导率下降。此外，发现页岩裂缝的水力孔与有效应力之间的关系是双曲线的。由于超临界CO ₂的影响，页岩裂缝电导率的变化主要是由于页岩裂缝表面粗糙度的增加和裂缝变形抗力的降低。已经观察到页岩裂缝中的非线性气体流动行为，可以用Forchheimer方程来描述。提出了一种基于雷诺数和相对粗糙度的摩擦系数模型，与经典的Lomize模型相比，该模型可以更准确地反映页岩裂缝中瓦斯的流动方式。