Improved Depth Imaging by CRS Signal Enhancement in Input Shot Gathers

Abstract

Noise suppression and signal enhancement prior to prestack depth migration (PreSDM) may significantly increase the resolution of the depth image, and the effectiveness of the PreSDM workflow. The Common-Reflection-Surface (CRS) technique was previously used for this enhancement of seismic prestack data, providing so-called CRS gathers with regularized CMP and offset coverage, and with a strong noise suppression. These CRS gathers considerably improved the depth image in Kirchhoff PreSDM but were not suited for shot-based PreSDM algorithms. This case study now presents a straightforward way to produce geometry-preserving CRS gathers that similarly increase the signal-to-noise ratio. In a first implementation, CRS prestack data interpolation is performed at the existing trace locations providing a straightforward and automatic preservation of the original shot geometry. Application to 3D seismic land data demonstrates the improved signal-to-noise ratio and resolution both in the geometry-preserving CRS shot gathers, and in the corresponding QC stack. As in the Kirchhoff migration of regularized CRS gathers, such enhancements are expected for Reverse Time Migration of CRS shot gathers as well.