Effect of liquid nitrogen freeze–thaw cycle on fracture toughness and energy release rate of saturated sandstone

To enhance the ability of tight sandstone gas extraction, liquid nitrogen (LN2) freeze–thaw cycle method can be employed to improve the physical and mechanical properties of the sandstone. Rock fracture behaviors and mechanical properties after fracturing play an important role to successfully implement reservoir stimulation. Since tight sandstone gas reservoirs are usually characterized by high water content, the influences of LN2 freeze–thaw...