The pore structure heterogeneity of ultra-low tight sandstone has a direct impact on the exploration development and sustainable production of tight sandstone gas. In this study, high pressure mercury injection and casting thin sections methods were conducted to study the physical properties and pore structures of Carboniferous–Permian (C–P) tight sandstone reservoirs. Then, the multifractal behaviors of the pore structures and their genetic mechanisms were revealed by establishing the relationships of the multifractal parameter (spectral width of singular spectrum Δα (Δα = α_-10–α₁₀₊)) with the petrophysical properties and the lithologic characteristics parameters. The results showed that the multifractal characteristics of the pore throat structure in the C–P sandstone were objective and that the C–P sandstone reservoir of higher mesopores volume tended to display greater pore structure heterogeneity. Moreover, the C–P tight sandstone samples with high debris and less content levels of quartz and feldspar showed stronger pore structure heterogeneity. Furthermore, there was a negative correlation between pore structure heterogeneity and interstitial material while increases in matrix (clay minerals) content and decreases in carbonate and quartz cement had potentially led to the enhancement of pore structure heterogeneity. Additionally, the double effects of tectonic stress caused some of the C–P sandstone samples to display characteristics of strong heterogeneity, low porosity and low permeability.

超低致密砂岩孔隙结构非均质性直接影响致密砂岩气勘探开发和可持续生产。本研究采用高压压汞法和薄层铸造法研究石炭-二叠系（C-P）致密砂岩储层的物性和孔隙结构。然后，通过建立多重分形参数（奇异谱的谱宽Δα ( Δα  =  α _-10 – α ₁₀₊)) 具有岩石物理性质和岩性特征参数。结果表明，C-P砂岩中孔喉结构的多重分形特征较为客观，中孔体积较大的C-P砂岩储层往往表现出较大的孔隙结构非均质性。此外，C-P致密砂岩样品中碎屑含量高、石英、长石含量低的样品表现出更强的孔隙结构非均质性。此外，孔隙结构非均质性与间隙材料呈负相关，而基质（粘土矿物）含量的增加以及碳酸盐和石英胶结物的减少可能导致孔隙结构非均质性的增强。此外，