Fractal characteristics analysis of pore structure in tight sandstone reservoirs of the He 8 member, Shihezi formation: eastern Ordos Basin

The He 8 member in the eastern Ordos Basin is an important reservoir and requires further investigation to fully characterise the pore structure of this tight sandstone reservoir. Casting thin sections and SEM analysis were utilised to qualitatively examine the varieties of pore and throat types within the He 8 member reservoir. Combined with capillary pressure curve morphology, pore-throat distribution, and structure parameters, the characteristics of pore and throat size distribution were quantitatively assessed, and the pore-throat assemblage patterns were summarised. Twelve representative samples were chosen to investigate the fractal characteristics of the reservoir's pore structures through fractal theory. The findings suggest that there are four types of pore-throat assemblage patterns within the target reservoir. The fractal dimensions of macropores and mesopores exhibit a strong correlation with porosity, permeability, and pore structure parameters. The mineral composition and the content within the reservoir serve as inherent factors determining the fractal dimension. [Received: October 22, 2024; Accepted: January 15, 2025]