Tight sandstone formations are important reservoirs for the development of unconventional oil, gas, and geothermal resources. However, due to their strong heterogeneity, the fracture development characteristics of tight sandstone under artificial hydraulic fracturing are difficult to identify. This article focuses on the Shaximiao Formation tight sandstone in the Sichuan Basin, using large-scale true triaxial physical simulation experiments and hydraulic fracturing monitoring results at an engineering scale. Based on large-scale true triaxial physical simulation and engineering-scale fracturing monitoring data, this study identifies the fracture development characteristics of tight sandstone and reveals its fracturing mechanism by utilizing the spatiotemporal distribution of microseismic events induced by multi-scale fractures.The research shows that: (1) Fracture development is controlled by twofold factors: first, the combined effect of natural fractures and artificial fracture networks; second, the external influences of sedimentary facies (channel sandbody distribution), formation dip angle, and natural fracture development degree. These factors ultimately result in fractures exhibiting heterogeneous and multi-scale reticular fracturing characteristics.; (2) Reservoir physical properties determine the rupture effect. Low-porosity, low-permeability formations lead to high fracture pressure, and microseismic events are densely distributed in intervals with high brittleness index and high porosity, resulting in complex fractures and a significant increase in the stimulated reservoir volume (SRV). Conversely, fracture development is restricted in less favorable conditions; (3) The rupture mechanism is a multi-factor coupling mechanism. Geological factors (brittle mineral content, bedding anisotropy) and mechanical factors (stress differences) work together to form a tension-shear composite rupture mode.
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