关键词: 含气页岩, 渗透率, 变形, 围压敏感性, 各向异性

Abstract: MTS has been used to study the effects of confining pressure on permeability, deformation and the anisotropic characteristics of Niutitang gas shale. SEM has also been used to observe the samples' microstructure, which reveals the real reason of the confining pressure effect. The results show that: 1) The Niutitang gas shale permeability is between 5.06×10-7 D and 1.02×10-5D as the confining pressure raises from 0 to 40 MPa; 2) The gas shale permeability decreases with the increment of confining pressure, which obeys a power-law relationship, but the volume deformation of shale increases as confining pressure gradually increases; 3) The gas shale permeability and deformation are anisotropic, that is, under the same confining pressure, the permeability and volume deformation of sample paralleled to bedding plane are both greater than the sample with beddings at an angel of 45 degrees to the plane; 4) Obvious sedimentary structure is observed in the gas shale samples, and the pores distribute along the direction of the bedding; 5) The volume strain sensitivity to the confining pressure of low permeability gas shale decreases after an initial increase with the increase of confining pressure, and the permeability sensitivity to the confining pressure is gradually reduced with the increase of confining pressure.

Key words: gas shale, permeability, deformation, sensitivity to confining pressure, anisotropy