Abstract:
In order to improve the static correction effect of seismic data in complex near-surface area, the tomography velocity modeling and target-driven static correction method based on vertical transverse isotropy (VTI) medium were studied. The forward simulation introduces the anisotropic parameters into the linear travel-time interpolation (LTI) ray-tracing algorithm, and establishes the formula for calculating the first breaks travel time in VTI media. The iterative inversion adopts the least square QR decomposition (LSQR) algorithm and incorporated regularization constraint factors in the inversion process. In the static correction processing, the quantities of datum plane static correction and the model-based residual static correction were calculated separately, and the two kinds of statics were combined and compared, then the target driven static correction analysis was carried out. The results show that the influence of anisotropy on seismic wave propagation increases with the increase of offset, and when considering the influence of geological anisotropy, the first break travel time calculated in VTI media has higher accuracy. The LSQR inversion algorithm with regularization constraints can effectively improve the stability of the inversion solution, and the tomography inversion method based on VTI medium can obtain a more precise near-surface velocity model. The datum statics corrects seismic data to the unified horizontal plane, which mainly solves the problem of long wavelength statics and ensures the correct imaging of structural form. The residual statics is to compensate for the residual static correction after the datum plane static correction, solve the short-wavelength static correction problem, and further improve the imaging accuracy. Theoretical numerical calculation and actual data processing results verify the correctness and effectiveness of the proposed method, which can obtain more accurate near surface velocity models and field static correction quantities, effectively solving the static time shift problems caused by complex near surface seismic data, which is beneficial for high-resolution seismic imaging.