Liquid carbon dioxide phase change fracturing (LCPCF) technology can effectively increase the coal permeability. In order to evaluate the influence of LCPCF on pore structure and permeability characteristics of coal, mercury intrusion porosimetry (MIP) analyses and permeability tests were used in this study. The experimental results show that LCPCF has less effect on transition pores, but it indeed has significant influence on pores (> 100 nm) and fracture structure of coal, further affecting the gas permeability characteristics within coal. This influence is heavily dependent on the distance from the fracturing borehole. When 1.26 L of liquid CO₂ (weighing 1.25 kg–1.40 kg) was used to conduct physical blasting, according to the change trends of pore/fracture and gas permeability within coal, the influence degree of LCPCF on coal can be divided into three stages at the distance of 0.2–1.0 m, 1.0–6.0 m and > 6.0 m, respectively. For the first stage, the influence of LCPCF is strengthened, and mesopores within coal are reduced and shift to the larger pores under the effect of high-energy gas and shock wave, leading to the increase in the number of macropores and microfractures, which in turn improves the gas permeability of coal to a large degree. At the second stage, due to the energy attenuation of shock wave and high-pressure CO₂ gas, the fracturing effect of LCPCF is reduced with the distance increasing from 1.0 m to 6.0 m, and the increase of coal permeability is rapidly diminished. At the third stage, both the change rates of pore structure and permeability characteristics of coal tend to be stable over 6.0 m away from the fracturing borehole, indicating that the influence scope of LCPCF is approximately 6.0 m for a single fracturing borehole.

液态二氧化碳相变压裂（LCPCF）技术可以有效地提高煤的渗透率。为了评估LCPCF对煤的孔隙结构和渗透性特征的影响，本研究采用了压汞法（MIP）和渗透性试验。实验结果表明，LCPCF对过渡孔的影响较小，但确实对孔（> 100 nm）和煤的断裂结构有显着影响，进一步影响了煤的透气性。这种影响在很大程度上取决于距压裂井眼的距离。当1.26 L的液态CO ₂用重达1.25 kg-1.40 kg的煤进行物理爆破，根据煤中孔隙/裂缝和气体渗透率的变化趋势，LCPCF对煤的影响程度可分为0.2-1.0范围内的三个阶段。 m，1.0–6.0 m和> 6.0 m。在第一阶段，LCPCF的影响增强，煤中的中孔减少，并在高能气体和冲击波的作用下移向较大的孔隙，导致大孔和微裂缝的数量增加，从而反过来在很大程度上提高了煤的透气性。在第二阶段，由于冲击波和高压CO ₂的能量衰减随着距离的增加，LCPCF的压裂效果降低，从1.0 m增加到6.0 m，而煤渗透率的增加迅速减小。在第三阶段，煤的孔隙结构变化率和渗透率特性在距压裂井6.0 m处趋于稳定，这表明LCPCF对单个压裂井的影响范围约为6.0 m。