Preserved-amplitude angle domain migration by shot-receiver wavefield continuation

Abstract

We present preserved-amplitude downward continuation migration formulas in the aperture angle domain. Our approach is based on shot-receiver wavefield continuation. Since source and receiver points are close to the image point, a local homogeneous reference velocity can be approximated after redatuming. We analyse this approach in the framework of linearized inversion of Kirchhoff and Born approximations. From our analysis, preserved-amplitude Kirchhoff and Born inverse formulas can be derived for the 2D case. They involve slant stacks of filtered subsurface offset domain common image gathers followed by the application of the appropriate weighting factors. For the numerical implementation of these formulas, we develop an algorithm based on the true amplitude version of the one-way paraxial approximation. Finally, we demonstrate the relevance of our approach with a set of applications on synthetic datasets and compare our results with those obtained on the Marmousi model by multi-arrival ray-based preserved-amplitude migration. While results are similar, we observe that our results are less affected by artefacts. © 2010 European Association of Geoscientists & Engineers.