Amplitude-Versus-Angle Analysis of Local Angle-Domain Common Image Gathers With Prestack Gaussian-Beam Migration of Seismic Data

The analysis of seismic reflection amplitude versus angle/amplitude versus offset (AVA/AVO) is an important tool for investigating the physical properties of subsurface rocks and/or reservoirs. We propose to generate local angle-domain common image gathers (ADCIGs) from the surface-recorded seismic data for AVA analysis via Gaussian-beam migration (GBM) using a deconvolution imaging condition. The traditional seismic reflection amplitude analysis is often based on the AVO response from common middle point (CMP) gathers. However, the AVO analysis based on the horizontally layered medium assumption can achieve success only in simple geological cases. Our approach provides an AVA response during the migration process that reveals true local physical properties in the image domain even if the image point is at a tilted interface or has a complicated overburden geological structure. We test our approach with a two-layer velocity model with a tilted interface, and with the benchmark Marmousi2 model that has a complicated geological structure. From these two numerical examples, we demonstrate that our method faithfully provides the AVA response that can be used to further interpret the rock/reservoir physical properties.