Experimental Investigation On Gas Permeability In Bedding Shale With Brittle And Semi-Brittle Deformations Under Triaxial Compression

This study investigates the stress-strain behavior, failure deformation, and change of gas permeability in shale under compressive stress induced failure. The study is based on triaxial compression of shale from Lower Silurian Longmaxi Formation, South China at different angle of bedding planes. It was found that shale behaves as a brittle materials and exhibits brittle and semi-brittle response to peak strength load at different angles of pre-exist bedding during stress compression. The gas permeability increased after failure deformation for all shale samples. However, samples under vertical and horizontal bedding angles exhibited brittle deformation and significant increase in permeability. While the samples with bedding angles of 30 degrees and 60 degrees showed semi-brittle deformation, and the permeability increased slightly after failure. These results indicate that the pre-existing structure influences the mechanical behavior of shale, which consequently affects its gas permeability. The results of this study are of great significance in shale gas exploration and development in areas of South China which has complex tectonic and pre-existing foliation structures.