The accurate extraction of pore-throat information, particularly in pore-throat size, pore connectivity, and pore morphology, is of great significance for the physical transport of porous media. However, traditional methods for pore-throat information extraction often rely on petrophysical methods, exhibiting evident weakness in achieving visual and quantitative characterization. In this article, an integrated analysis of petrography, micro-computed tomography (CT), and conventional petrophysical methods (X-ray diffraction, casting thin section, and scanning electron microscopy) was combined to realize visual and quantitative characterization of pore structure in tight sandstone reservoirs. Based on CT and image processing technology, a three-dimensional (3D) digital core model was reconstructed. Characteristic parameters describing pore morphology, shape factor, sphericity, and equivalent diameter were defined, and the quantitative classification of 3D pore morphology was carried out. The results reveal that the predominant pore types in the study area are primary intergranular pores, intergranular dissolved pores, intra-granular dissolved pores, and inter-crystalline pores, and typical types of throats are necked, lamellar, and lamellar curved throats. Moreover, the pore structure of tight sandstone consists of both isolated pores and interconnected pores, and the volume of interconnected pores accounts for 83.47% of the total pore volume, while the volume of isolated pores accounts for an average of 16.53% of the total pore volume. In addition, the pore–throat ratio is mainly distributed between 2 and 7, and the coordination number is mainly distributed between 1 and 5. Besides, the pore morphologies of tight sandstone are classified into spherical pores, triangular pores, banded pores, and harbor-like pores. Specifically, spherical pores and triangular pores dominate in pore number, but minimally in pore volume and surface area. In contrast, banded pores and harbor-like pores together constitute the majority of the pore volume (>80.64%) of the Penglaizhen Formation in the Sichuan Basin. This study enables accurate characterization of microscopic pore-throat features in tight sandstone reservoirs and provides a strong theoretical support for the subsequent research on physical transport in tight sandstone reservoirs.
Yuan et al. (Wed,) studied this question.