不同泥质含量砂岩三轴渗透试验研究

为探讨三向应力状态下不同泥质胶结物含量砂岩渗透力学性能的异同，对泥质含量分别为4%、15%、24%、31%的4组不同泥质含量砂岩进行了三轴压缩渗透试验。试验结果表明:砂岩的强度和弹性模量随着泥质胶结物的增加呈幂函数型减小，随围压的升高而增大，内摩擦角和黏聚力随含泥量增加而逐渐减小；相同围压和泥质含量下，渗透性随加载应力的增大呈先减小后增大、再略微减小的整体趋势，渗透系数在峰值应力附近达到最大值；相同围压和偏应力下，渗透系数随泥质胶结物含量的升高而呈线性减小；同等泥质含量和偏应力下，砂岩的渗透性随围压的升高呈对数型函数减小。基于试验结果，分析得到了一种综合考虑围压、孔隙度以及泥质含量影响的砂岩综合渗透模型，并通过理论与试验数据对比分析验证了模型的合理性。

An experimental study on permeability of sandstone with different shale contents under 3-D stress conditions

In order to examine the difference in permeability and mechanical properties of sandstones in the three direction stress state, the permeability tests are carried out on shale contents of 4%, 15%, 24% and 31%. The research results show that the strength and elastic modulus of sandstones decrease with the increasing clay cement, and decrease with the increasing confining pressure, and the internal friction angle and cohesive force decrease with the increasing clay content. Permeability with increasing stress decreases first and then increases again slightly in the overall trend under the same confining pressure and clay contents, and the permeability coefficient in the peak stresses near the maximum. The permeability coefficient decreases linearly with the increasing contents of the cement under the same confining pressure and the partial stress. The permeability of sandstones decreases with the increasing confining pressure. Based on the experimental results, a comprehensive model of sandstone permeability considering confining pressure, porosity and shale content is obtained. The rationality of the model is verified by the comparison of the theoretical and experimental data.