页岩属于低渗致密岩石,页岩储层渗透性是页岩气开采过程中的关键问题,基于岩石力学三轴渗透性试验,研究黔北下寒武统牛蹄塘组页岩渗流-损伤演化过程的特征。试验结果表明:页岩渗透率的变化与损伤作用与应力状态有着很强的关联性,页岩损伤演化过程存在不同阶段性特点,损伤主要发生在弹塑性变形阶段与在应变软化阶段;页岩渗透率演化落后于页岩损伤破坏演化过程;中等围压条件下试样出现局部变形带压缩带,造成页岩渗透率有一定程度的减小,压缩带是造成了页岩渗透率演化过程落后于页岩损伤破坏演化过程的原因。
Permeability of shale reservoirs is a key issue in shale gas extraction. Based on the triaxial permeability test of rock mechanics, the characteristics of shale seepage-damage evolution of Niutitang Formation of Lower Cambrian in northern Guizhou were studied. The experimental results showed that the shale damage evolution process has different stages. Damage occurs mainly in the elastoplastic deformation stage and in the strain softening stage. Shale permeability evolution is behind the shale damage evolution process. The compressive zone of the test specimen under medium confining pressure resulted in the shale permeability decreasing to a certain extent. The compression zone is the cause of shale permeability evolution lag behind shale damage evolution process.