Azimuthal traveltime analysis provides comparatively stable fracture-orientation estimates but limited information on fracture-related elastic changes, whereas amplitude variation with offset (AVO) inversion is sensitive to residual azimuthal moveout. We propose a sequential offset vector tile (OVT)-domain azimuthal traveltime-constrained AVO inversion workflow for reservoir-scale fracture characterization. Traveltime responses are first used to estimate the locally dominant fracture orientation and reduce azimuth-dependent event misalignment. Prestack AVO inversion is then applied separately to representative fracture-parallel and fracture-perpendicular gathers to obtain two sets of apparent elastic parameters, from which a relative tangential-weakness attribute ($\Delta e$) and Poisson’s ratio ratio ($R_{\nu }$) are derived. Synthetic tests show that the mean fracture-orientation error is no greater than 1.1° for prescribed noise levels of 0–50%, and that varying the maximum incidence angle from 20° to 40° causes no systematic deterioration in the recovered attributes. In the field application, the predicted dominant orientation of N 45° E–N 60° E agrees with the approximately N 50° E fracture trend identified from an independent structure-tensor-based seismic interpretation near ZT3. Compared with the uncorrected results, the corrected $\Delta e$ and $R_{\nu }$ maps exhibit improved continuity and better spatial correspondence with the independently interpreted fracture pattern. These results demonstrate that the proposed workflow effectively integrates the stable directional constraint provided by azimuthal traveltime analysis with the fracture-related elastic information obtained from directional AVO inversion, enabling reservoir-scale characterization of the dominant fracture orientation, relative fracture-related weakness variation, and possible fluid sensitivity. Within the stated assumptions and applicability conditions, the method provides a practical seismic framework for fractured-reservoir characterization and evaluation.

Surface seismic data often suffer from limited bandwidth and uneven illumination, which degrade PSDM (prestack depth migration) in deep and structurally complex settings. VSP (vertical seismic profiling), particularly DAS-VSP, provides a higher signal-to-noise ratio and richer high-frequency content near the wellbore but has a limited lateral imaging aperture. To exploit the complementary strengths of these two observation systems, we propose an OVT domain (offset vector tile) joint Kirchhoff prestack depth migration workflow that integrates surface seismic and VSP data within a unified depth domain framework. The workflow includes wavelet (amplitude–phase) matching, consistent datuming, joint well–surface tomographic velocity model building using both surface CIG (common image gather) residual moveout and VSP first-arrival constraints, efficient travel time table construction based on 3D eikonal solvers, OVT domain joint migration, azimuth-dependent CIG depth correction for anisotropy, and ray-based illumination compensation for amplitude balancing. Synthetic tests demonstrate that the proposed method improves reflector continuity and increases the effective bandwidth of the joint image relative to surface-only PSDM. A field application in the northwest Sichuan Basin further shows that the joint imaging better matches well synthetics in the target interval, increasing the correlation coefficient from 0.753 (surface-only) and 0.738 (VSP-only) to 0.787 (joint) while reducing inter-azimuth CIG depth residuals to within 3 m after anisotropy correction. These results indicate that OVT domain joint imaging can enhance thin-bed resolution and near-well structural delineation, providing a practical multi-source data fusion solution for high-fidelity depth imaging in complex reservoirs.