为了明晰超临界CO₂脉动作用对低阶煤的作用效果及机理，采集新疆艾维尔沟矿深部低阶煤作为试验对象，通过自主搭建的超临界CO₂脉动致裂试验系统开展试验研究，对脉动作用前后的煤样分别进行XRD、FTIR、低温液氮吸附试验、低场核磁共振及单轴压缩试验测定，量化分析超临界CO₂脉动作用前后煤体的微观结构、孔隙结构及力学特性变化。结果表明：超临界CO₂脉动作用后，煤中方解石和黏土矿物的质量分数增加，黏土矿物质量分数的变化主要受氨伊利石增加的影响，煤中各有机官能团峰值均呈现不同程度的降低，超临界CO₂对有机物的萃取作用效果明显，脉动作用后煤体的微晶结构受到损伤，晶体层片间距增加了0.002 9 nm，煤体结构趋于松散；对比超临界CO₂脉动作用前，作用后煤样XJ-A、XJ-B有效孔隙度分别提高了66.7%、128.6%，煤体内部孔隙连通性增强，脉动作用对微小孔及中孔的改造作用更明显；超临界CO₂脉动作用后煤的力学特性显著劣化，单轴抗压强度和弹性模量分别降低54.73%和59.82%，声发射振铃计数和累积能量均大幅降低，振铃计数峰值降至作用前51%，煤样内部颗粒黏聚力降低，累积能量降低了62%。综上，超临界CO₂脉动作用能够显著破坏低阶煤的微观－宏观结构，对深部低阶煤储层致裂增透、煤层气抽采具有重要意义。

In order to clarify the effect and mechanism of supercritical CO₂ pulsation on low-rank coal, deep low-rank coal from the Aiwiergou Mine in Xinjiang was collected as the experimental object. Experimental research was carried out through an independently built supercritical CO₂ pulsation fracturing experimental system. Before and after the pulsation, the coal samples were respectively measured by XRD, FTIR, low-temperature liquid nitrogen adsorption test, low-field nuclear magnetic resonance, and uniaxial compression test. The changes in the microscopic structure, pore structure, and mechanical properties of the coal before and after the supercritical CO₂ pulsation were quantitatively analyzed. The results show that after the supercritical CO₂ pulsation, the mass fractions of calcite and clay minerals in the coal increase. The change in the mass fraction of clay minerals is mainly affected by the increase of ammoniated illite. The peak values of various organic functional groups in the coal show different degrees of decrease, indicating that the extraction effect of supercritical CO₂ on organic matter is obvious. After the pulsation, the microcrystalline structure of the coal is damaged, the crystal lamellar spacing increases by 0.002 9 nm, and the coal structure tends to be loose. Compared with before the supercritical CO₂ pulsation, the effective porosities of coal samples XJ-A and XJ-B increase by 66.7% and 128.6% respectively after the pulsation. The connectivity of pores inside the coal is enhanced, and the pulsation has a more obvious effect on the modification of micropores and mesopores. After the supercritical CO₂ pulsation, the mechanical properties of the coal deteriorate significantly. The uniaxial compressive strength and elastic modulus decrease by 54.73% and 59.82% respectively. The acoustic emission ring-down count and cumulative energy are both greatly reduced. The peak value of the ring-down count drops to 51% of that before the pulsation, the cohesion of internal particles in the coal sample decreases, and the cumulative energy decreases by 62%. In conclusion, the supercritical CO₂ pulsation can significantly damage the micro-macro structure of low-rank coal, which is of great significance for the fracturing and permeability enhancement of deep low-rank coal reservoirs and the extraction of coalbed methane.