Experimental and numerical modelling of the mechanical behaviour of low-permeability sandstone considering hydromechanics.

• A novel approach is used to obtain the relationships of the porosity and the permeability of low-permeability rock. • The logarithmic bulk modulus was obtained from the gas permeability experiments. • The tested parameters make the fluid-solid coupling simulation of low permeability sandstone a reality. • Numerical simulations of low-permeability sandstone are conducted based on the triaxial compression experiments. This paper proposed a novel approach, which combines an analytical model and a formula fitting function, to determine the hydromechanical relationships between the porosity and the permeability of low-permeability sandstone (LPS) that is further applied for the hydromechanical modelling. Then, several gas permeability experiments are conducted to measure the permeability and porosity of LPS under different confinement pressure. In conjunction with the Finite Element Method, the fracture propagation processes of LPS, which take physical triaxial experiments as reference experiments, are simulated by the considering hydromechanics. The results demonstrate that the absolute permeability is exponentially related to the porosity of LPS. Additionally, the porous media nonlinear elastic model and the modified Drucker–Prager cap plasticity model can accurately describe the deformation process of LPS. The simulation results correlate well with the experimental counterparts while being less scattered than the experimental data. This demonstrates the effectiveness of the proposed method in characterizing fracture properties of LPS considering hydromechanics. [ABSTRACT FROM AUTHOR]