Liquid nitrogen (LN₂) fracturing has various advantages, such as low reservoir damage, minimal environmental impact, and excellent permeability. In this study, the cracking pattern and damage evolution characteristics of bedded coal subjected to LN₂ fracturing were investigated. The deterioration features of the mechanical parameters and failure mechanisms were examined in a comparable manner using Brazilian splitting tests. Additionally, the damage characteristics of bedded coal during LN₂ fracturing were explored. The results indicated that LN₂ cooling promoted the development of thermal cracks, consequently reducing the effective bearing capacity of the coal. Randomly distributed thermal cracks actively contributed to macroscopic crack propagation, increasing the proportion of shear cracks and the complexity of the fracture surface. Different bedding angles led to distinct failure modes, significantly impacting the proportion of shear cracks and the fracture surface complexity. Moreover, the bedding planes constantly influenced the propagation direction of the fracturing cracks, resulting in a macroscopic damage zone that expanded preferentially at the weak bedding planes with the borehole at the center. With increasing bedding angles, both the degree and rate of damage of coal decreased sequentially. Consequently, it was feasible to employ LN₂ fracturing in low-permeability reservoirs along the bedding planes, facilitating swift and efficient reservoir fracturing.

液氮(LN ₂ )压裂具有储层伤害低、环境影响小、渗透率优良等优点。本研究主要研究了层状煤经LN ₂压裂后的开裂模式和损伤演化特征。使用巴西劈裂试验以类似的方式检查机械参数和失效机制的恶化特征。此外，还探讨了LN ₂压裂过程中层状煤的损伤特征。结果表明，LN ₂冷却促进了热裂纹的发展，从而降低了煤的有效承载力。随机分布的热裂纹积极促进了宏观裂纹扩展，增加了剪切裂纹的比例和断裂表面的复杂性。不同的层理角度导致不同的破坏模式，显着影响剪切裂纹的比例和断裂表面的复杂性。而且层理面不断影响压裂裂纹的扩展方向，导致宏观损伤区优先在以钻孔为中心的软弱层理面处扩展。随着层理角度的增大，煤体的破坏程度和破坏率依次降低。因此，在低渗透油藏沿层理面进行_液氮压裂是可行的，有利于油藏压裂的快速高效。