Precise Near-surface Interval Velocity Section Derived from High-resolution Shear Wave Seismic Data

Abstract

Partial Common Reflection Surface (CRS) Stack and Normal-Incident-Point-wave (NIP-wave) tomographic methods are applied to high resolution shallow reflection seismic data in order to obtain enhanced image of subsurface with the target up to 1.2 s (shallow target) and more precise interval velocity section. A ca. 600 m long high-resolution multichannel SH-wave reflection seismic land profile in the Trondheim harbor area was accordingly reprocessed. Partial CRS Stack method is the generalization of ZO CRS-Stack which has an ability to provide more detail information about subsurface, which consist of emergence angle and the two radii of wavefront curvatures RNIP and RN. Those CRS attributes extracted from prestack seismic data by using optimization scheme and coherence analysis in order to obtain the best stacking surface in every ZO sample. Since the final product of Partial CRS-Stack is CRS supergathers, which are regularized and have better signal-to-noise ratio compared to original CMP gathers, one could implement better and easier velocity analysis after applying this method. Moreover, the CRS attributes could be used as input for NIP-wave tomography in order to determine macro velocity model in depth. This velocity model could then be used as input for Prestack Depth Migration.