Application of the partial CRS-stack and NIP-wave tomography methods to 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. This paper will describe only the shear wave seismic main reprocessing of the data that has been conducted by new approaches. Interpretation related to the data will not be explained. Partial CRS Stack method is developed for the first time by Baykulov in 2008, which is the generalization of ZO CRS-Stack that is introduced in 1999 by WIT Consortium in Germany. Similar to ZO CRS-Stack, Partial CRS attributes has also an ability to provide more detail information about subsurface, which consist of emergence angle and the two radii of wavefront curvatures RNIPand 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 velocity analysis after applying this method. Thus, the stacking velocity based on obtained CRS supergathers will be better than the one that is obtained from conventional stacking 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, since the velocity model is more precise than the conventional stacking velocity.