页岩支撑裂缝中渗透率变化规律实验研究

在页岩气藏的压裂开发中，支撑裂缝的渗透率是影响裂缝导流能力和压裂增产效果的重要因素。通过实验
手段，研究了吸附气体的溶胀作用和支撑剂的嵌入作用对Greenriver 页岩支撑裂缝渗透率的影响。采用Pulse test 实
验方法，测量并对比了非吸附气体和吸附气体的渗透率。以He 为代表性的非吸附性气体，实验测得其在花岗岩和页
岩中的渗透率曲线为线性，渗透率随着有效应力的减小而增加，且支撑剂的嵌入作用使页岩中的渗透率明显降低；以
CO2 为代表性的吸附性气体，实验测得其在页岩中的渗透率曲线呈典型的“U”型，这是由于CO2 溶胀作用和有效应力
共同作用的结果，从而说明在页岩支撑裂缝中，溶胀作用同样对渗透率有显著影响；与He 在页岩中的渗透率相比，相
同压力下的CO2 渗透率更低，且在Langmuir 压力值附近达到最小值。

Experimental Study on Permeability Evolution in Propped Shale Fracture

In the process of shale gas fracturing exploitation，the permeability of propped shale fracture is one of the key
factors that affect the fracture conductivity. This work focuses on the effects of swelling and embedment on permeability in
propped shale using experimental method. The Pulse test method was used to measure the permeability of adsorbed gas and
non-adsorbed gas. The permeability of He，which is a non-adsorbing gas，in both granite and shale was measured for references.
The reduction of permeability in shale is caused by the existence of proppant embedment. The“U shape”feature is observed in
CO2 permeability curve，which indicates that the swelling also has a significant effect on the permeability in shale. Compared
with the permeability curve of He，the CO2 permeability is even lower and achieves the minimum value at the pressure condition
around the Langmuir pressure.