Reservoir Characterization of Tight Sandstone Gas Reservoirs: A Case Study from the He 8 Member of the Shihezi Formation, Tianhuan Depression, Ordos Basin

Tight sandstone gas reservoirs, characterized by low porosity (typically 70% of total clays), act as the main interstitial material. Reservoir properties average 7.01% porosity and 0.5 × 10⁻3 μm2 permeability, defining a typical low-porosity, ultra-low-permeability system. Vertically stacked sand bodies in the He 8 Member display large single-layer thicknesses (5–12 m) and moderate sealing capacity (caprock breakthrough pressure > 8 MPa), hosting gas–water mixed-phase occurrences. Rock mechanics experiments demonstrate that fractures enhance permeability by >60%, significantly controlling reservoir heterogeneity.