• NMR T2 spectrum effectively characterizes fracture development and pore structure changes in coal after hydraulic fracturing.
• Fractal dimension of T2 spectrum quantitatively evaluates fracture complexity, correlating with fracturing effectiveness.
• NMR-derived parameters (e.g., porosity, permeability) show strong correlation with gas production, enabling production prediction.
• The proposed NMR-based evaluation method aids in optimizing fracturing design and improving CBM well performance.