Fluorescence thin section and scanning electron microscopy (SEM) analysis were performed to delineate pore spaces and pore network assemblages of oil shales of Member 2 of Paleogene Funing Formation (E₁f₂) in Subei Basin, China. Nuclear magnetic resonance (NMR) T₂ (transverse relaxation time) spectra were used to gain insight into pore size distribution. Fractal analysis was performed on the NMR T₂ spectra measured at saturated and centrifugal status, respectively, with the aim to reveal the different fractal behaviors of irreducible pore realms (centrifugal T₂ spectrum) and the entire pore systems (saturated T₂ spectrum). Relationships between NMR parameters and fractal dimensions were revealed. The results show that the pore spaces consist of 1) large pore realms including interparticle pores, and microfractures, 2) small pore realms including intragranular dissolution pores, intercrystal micropores and organic matter pores. The T₂ spectra are mostly bimodal and left-skewed due to abundance in small pore realms. The right peak or tail distribution is associated with large pore realms. Fractal analysis performed on saturated and centrifugal T₂ spectra show that fractal dimensions calculated from centrifugal T₂ spectrum are higher. In addition, fractal dimensions for centrifugal T₂ spectrum show negative correlation relationships with BVI and T_2cutoff values. The different fractal behaviors of saturated and centrifugal T₂ spectra reflect the complex pore assemblages in oil shales. The small pore realms determine the microscopic complexity, while large pore realms control the macroscopic reservoir quality of oil shales. However large pore realms (interparticle pores and micro-fractures) are not self-similar with the small pore realms, and can't be described by fractal dimension. Fractal analysis gives insights in the heterogeneous assemblage of pore systems and helps describe complexity of pore structure.

进行了荧光薄片和扫描电子显微镜（SEM）分析，描绘了苏北盆地古近纪阜宁组（E ₁ f ₂）第2段油页岩的孔隙空间和孔隙网络组合。核磁共振（NMR）T ₂（横向弛豫时间）光谱用于深入了解孔径分布。对分别在饱和和离心状态下测量的NMR T ₂光谱进行分形分析，以揭示不可还原孔域（离心T ₂光谱）和整个孔系统（饱和T ₂）的不同分形行为。光谱）。揭示了NMR参数与分形维数之间的关系。结果表明，孔隙空间包括：1）包括颗粒间孔隙和微裂缝的大孔隙域； 2）包括颗粒内溶解孔隙，晶体间微孔和有机质孔隙的小孔隙域。由于小孔域中的丰度，T ₂谱图大部分是双峰的并且是偏斜的。正确的峰或尾分布与大孔域相关。对饱和和离心T ₂光谱进行分形分析表明，从离心T ₂光谱计算出的分形维数较高。此外，离心T _2的分形维数光谱显示与BVI和T 2_截止值呈负相关关系。饱和和离心T ₂光谱的不同分形行为反映了油页岩中复杂的孔隙组合。小孔隙范围决定了微观复杂性，而大孔隙范围决定了油页岩的宏观储层质量。但是，大的孔域（粒子间的孔和微裂缝）与小的孔域不是自相似的，因此无法用分形维数来描述。分形分析可以洞察孔隙系统的非均质组合，并有助于描述孔隙结构的复杂性。