| To investigate the influence of binary gas (CO2 and CH4) on the permeability of shale for enhancing production from shale gas and CO2 sequestration. A study on shale sample from longmaxi Formation of lower Silurian in Sichuan Basin is presented. The laboratory experiments under two types of stress and different proportion of binary gas are conducted by the system named “triaxial seepage experimental system”. The results showed that: When the mixing binary gas ratio is constant，shale permeability decreased with the increase of gas pressure; Maintaining the constant pressure, the permeability of shale will change with the changing mixing binary gas ratio; the permeability of shale with pure CO2is minimum, while the permeability of shale with pure CH4is maximum. In the mixed binary gas, the lower CH4 concentration means the lower the permeability of shale;In the process of gas injection, gas pressure and pressure relief cause shale shouted, porous plastic deformation and adsorption hysteresis, which will cause the shale permeability change. |
