Near surface velocity variations influence the entire subsurface depth image. The subsurface angle gather is a key to judging the accuracy of velocity model. We propose an automatic velocity estimation method without horizon picking, which is an effective method to estimate the near surface velocity. In this method, interval velocity is perturbed and updated sequentially from the surface to the bottom using time windows. Time windows and their depth versions constrain the time and the depth ranges for the computation of semblance of angle gathers and velocity update. Horizontal semblance examines the flatness of the angle gather. Velocities making the angle gathers flat compose the new velocity model. We can recover a smooth velocity model for the near surface with this approach. We apply this method to synthetic and real land data sets to see its effectiveness for near surface velocity estimation. This method is efficient and can be employed to recover the entire velocity model.
Note: This paper was accepted into the Technical Program but was not presented at the 2020 SEG Annual Meeting.
