TTI anisotropic velocity modeling based on a smoothed surface for a piedmont zone

The complex surface and geological conditions of piedmont zones brings challenges to velocity modeling, structure identification, and reservoir prediction.To address this issue, a tilted transversely isotropic (TTI) anisotropic velocity modeling based on a smoothed surface was proposed.First, a smoothed surface close to the actual surface was taken as the reference plane for velocity modeling and imaging.Then, diving wave tomography was used to establish a near-surface velocity model, in which constant velocity values in the middle and deep layers were initially set.Subsequently, velocity calibration from vertical seismic profile (VSP) logging was carried out, combined with one-dimensional forward modeling of the imaging gather, so as to obtain the anisotropic parameters and establish the initial TTI anisotropic model for the piedmont zones.Finally, horizon-controlled tomography was utilized to achieve fast convergence and derive the final velocity model.Test results on field data have demonstrated the effectiveness of the proposed method, which may be helpful for oil and gas exploration in complex piedmont zones.