Supercritical carbon dioxide (SCCO) fracturing significantly enhances shale gas recovery, which is influenced by particle size. We soaked shale in SCCO and investigated the impact of SCCO on different particle sizes. Large-particle shales showed the largest percentage changes in specific surface area and total pore volume (54.11 %, 87.87 %; 58.59 %, 76.32 %) followed by small-particle size shales. This trend was also observed in other pore structure parameters. The particle-size effect is: Large-particle shale, with abundant microfractures, enhances SCCO flow and pore alteration. Small-particle shale's high specific surface area facilitates SCCO penetration. Medium-particle shale is less affected due to balanced interactions of these factors. Methane is primarily found in large and medium pores and microfractures. Methane adsorption in shale mainly involves multi-layer adsorption. Following SCCO treatment, pore fractures narrowed, increasing the proportion of methane molecules adsorbed as a single-layer. This study is crucial for evaluating the fracturing effects on shale gas wells.

中文翻译：

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超临界二氧化碳对不同粒径页岩孔隙结构及甲烷吸附的影响


超临界二氧化碳（SCCO）压裂显着提高了页岩气采收率，这受到粒度的影响。我们将页岩浸泡在 SCCO 中，并研究 SCCO 对不同颗粒尺寸的影响。大颗粒页岩的比表面积和总孔容变化最大（54.11%、87.87%；58.59%、76.32%），其次是小颗粒页岩。在其他孔隙结构参数中也观察到了这种趋势。粒度效应为：大颗粒页岩微裂缝丰富，增强SCCO流动和孔隙蚀变。小颗粒页岩的高比表面积有利于 SCCO 渗透。由于这些因素的平衡相互作用，中颗粒页岩受到的影响较小。甲烷主要存在于大、中孔隙和微裂缝中。页岩中甲烷的吸附主要涉及多层吸附。 SCCO 处理后，孔隙裂缝变窄，单层吸附的甲烷分子比例增加。这项研究对于评估页岩气井压裂效果至关重要。