<p>Fractal dimension calculation results summary.</p>

To date, researchers have not systematically investigated the geological characteristics of deep shale gas reservoirs in the Western Chongqing Block. Furthermore, the single technique remains insufficient for characterizing the complexity of their multi-scale pore structures. Therefore, this study integrates scanning electron microscopy (SEM), argon ion polishing-field emission scanning electron microscopy (AIP-FESEM), high-pressure mercury intrusion (HPMI), and low-pressure gas adsorption (LPGA) to qualitatively and quantitatively investigate the microscopic pore structure of shale gas reservoirs in the Western Chongqing block. Meanwhile, the pore fractal characteristics were analyzed based on HPMI and LPGA experiments using the mercury saturation model, the Frenkel-Halsey-Hill (FHH) model, and the volume-surface area (V-S) model. The results show that, first, the pore types of the samples in the Western Chongqing block include organic pores, intergranular pores, intragranular pores, intercrystalline pores, and interlayer fractures; second, micropores are the main contributors to the total pore volume, mainly developed in the three ranges of 0.45 ~ 0.5 nm, 0.55 ~ 0.6 nm, and 0.8 ~ 0.85 nm, followed by mesopores and finally macropores; finally, the macropores of the samples exhibit stronger heterogeneity and more complex pore-throat structures compared to mesopores. The heterogeneity of the pore structure is stronger than that of the pore surface, indicating a more complex internal pore structure. Additionally, the microporous structures of the samples are also characterized by relatively complex. The experimental results provide important guidance for the economical and efficient development of shale gas.迄今为止，研究人员尚未对渝西区块深部页岩气储层的地质特征开展系统性研究。此外，单一技术手段仍难以全面表征该类储层多尺度孔隙结构的复杂性。为此，本研究联合采用扫描电子显微镜（scanning electron microscopy, SEM）、氩离子抛光-场发射扫描电子显微镜（argon ion polishing-field emission scanning electron microscopy, AIP-FESEM）、高压压汞（high-pressure mercury intrusion, HPMI）与低压气体吸附（low-pressure gas adsorption, LPGA）等测试技术，对渝西区块页岩气储层的微观孔隙结构开展定性与定量研究。同时，本研究基于高压压汞与低压气体吸附实验数据，分别采用汞饱和度模型、Frenkel-Halsey-Hill（FHH）模型以及体积-表面积（volume-surface area, V-S）模型，对储层孔隙的分形特征进行分析。研究结果显示：其一，渝西区块样品的孔隙类型包括有机孔隙、粒间孔隙、粒内孔隙、晶间孔隙与层间裂缝；其二，微孔是总孔隙体积的主要贡献组分，主要发育于0.45~0.5 nm、0.55~0.6 nm以及0.8~0.85 nm三个孔径区间，其次为介孔，大孔占比最低；其三，与介孔相比，样品的大孔具备更强的非均质性，孔喉结构更为复杂；孔隙结构整体的非均质性强于孔隙表面的非均质性，表明储层内部孔隙结构更为复杂。此外，样品的微孔结构同样表现出较强的复杂性。本研究的实验结果可为页岩气的经济高效开发提供重要的理论指导与技术支撑。