Azimuthal Amplitude-Difference-Based Seismic Inversion for Tilted Fracture

Rock physics and borehole data indicate the presence of directionally aligned fractures with moderate dip angles within the formation. Accurate identification of these fractures is crucial for the efficient exploration and development of unconventional hydrocarbon reservoirs. To enhance the prediction accuracy of fracture parameters in fractured reservoirs, this study derives an approximate reflection coefficient equation for tilted transversely isotropic (TTI) media under the assumption of weak anisotropy. The proposed method is based on the anisotropy parameters (A-parameter) and incorporates linear-slip theory to establish a relationship between the A-parameter and fracture weakness parameters in VTI media. This relationship is further extended to TTI media through coordinate rotation. To achieve stable and reliable estimation of fracture-related parameters, we develop an amplitude-difference-based AVAZ inversion (ADI) workflow within a Bayesian framework. Tests on synthetic models demonstrate that the proposed method is robust to noise and provides accurate inversion results. Furthermore, applying the method to OBN seismic data from a field area in the East China Sea confirms its feasibility and effectiveness, with inverted results showing strong agreement with well log data. This study offers a novel, efficient, and reliable framework for fracture prediction and reservoir characterization in geologically complex settings.