Quantitative Evaluation of Fracture Stability Using TTI Pre-stack Depth Migration: A Methodological Study

This study addresses the technical challenges in assessing fracture stability within complex structural zones by proposing a novel quantitative evaluation method based on Tilted Transversely Isotropic (TTI) pre-stack depth migration. A comprehensive technical framework is established, integrating high-precision seismic imaging, multi-scale fracture parameter extraction, deep-domain geostress field prediction, and stability risk assessment. Key innovations include as follows: (1) Enhanced Imaging Resolution: The integration of TTI pre-stack depth migration with adaptive steering stacking technology significantly improves the identification accuracy of high-dip and small-scale fractures, overcoming the limitations of conventional methods in resolving complex geological structures. (2) Automated Parameter Extraction: Multi-scale algorithms combining structure tensor analysis and edge detection enable the automated extraction of geometric (e.g., strike, dip, curvature) and physical (e.g., fracture zone width, filling properties) parameters, validated through cross-correlation with downhole data. (3) Deep Stress Field Prediction: A geostress inversion model is developed using fused seismic attributes, coupled with an improved Mohr-Coulomb criterion. This model introduces the normalized slip tendency index (STnorm), establishing a three-tier risk classification system (low risk: STnorm < 0.6; moderate risk: 0.6 ≤ STnorm < 0.8; high risk: STnorm ≥ 0.8). (4) Field Validation: Case studies in the southern Sichuan shale gas region demonstrate a above 70% spatial consistency between predicted high-risk fracture zones and observed casing deformation events, significantly enhancing engineering early-warning precision. The proposed methodology not only advances fracture characterization in tectonically complex regions but also offers scalable solutions for hydrocarbon exploration, geological hazard mitigation, and underground engineering safety. Its integration of imaging, quantification, and dynamic risk assessment bridges critical gaps in geomechanically modeling and resource development strategies.