Experimental study on seepage-damage evolution of shale

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.