Pore structure and fractal characteristics of tight sandstone in meandering stream facies: a case study of the J2s2 member in the central Sichuan Basin, China

Based on porosity and permeability tests, high-pressure mercury injection (HPMI), nuclear magnetic resonance (NMR) centrifugal experiments, this study comprehensively analyzed the quality, pore structure fractal characteristics of tight sandstone reservoir in meandering stream facies. The purpose is to reveal relationship between physical properties, geometry topological parameters pores, fluid mobility heterogeneity system reservoirs results show that second member Middle Jurassic Shaximiao Formation (J 2 S ) central Sichuan Basin has developed fluvial facies, radius type I (K>0.3 mD) mainly distributed at 0.01 μm∼2 μm, tortuosity ranges 2.571 2.869, average movable saturation 70.12%. II (0.08mD<K<0.3 0.003 μm∼1 2.401 3.224, 57.59%. III (K<0.08 0.001 μm∼0.4 0.905 2.195, 13.46%. Capillary-Paraachor point (CP point) T2 cut-off value (T 2cutoff are used divide interval capillary pressure curve T spectrum. dimension D h2 small pores calculated by HPMI through 3D tube model, n1 large n2 NMR wetting phase model can effectively characterize pores. Among them, a strong negative correlation with porosity, permeability, saturation, indicating capacity, seepage capacity size controlled therefore, be as an effective evaluation parameter.