Residual moveout-based wave-equation migration velocity analysis in 3-D |

- Computation of a perturbation in the migrated image.
- Back-projection of the image perturbation into the velocity model using the image-domain wave-equation tomographic operator.

In the previous report (Zhang and Biondi, 2011), we proposed a new WEMVA method for maximizing the angle-stack power of ADCIGs. The key innovations in this method are as follows: first, we approximate the ADCIG, (migrated using the current slowness ), with the initial ADCIG followed by an RMO(Residual Moveout) on ; then we design a new image-space tomography operator that describes the kinematic relation between the model slowness perturbation and the RMO parameters. Using several 2-D examples, we have shown that this method: 1) avoids cycle-skipping, 2) does not require manual picking of the moveout parameters, and 3) can robustly improve the flatness of the angle gathers.

Although the three-dimensional extension of our method is conceptually straightforward, to actually implement a 3-D prototype requires substantial efforts on both the theoretical and practical aspects. In this paper, we present our initial work toward a 3-D implementation of our approach. The rest of the paper is organized as follows: First, we present the upgraded theory of our RMO WEMVA method for handling 3-D ADCIGs. Second, we discuss some of the challenges of transforming 3D common-image gathers (CIGs) between the offset and angle domains. We show a synthetic example as a prove of concept for our 3-D RMO WEMVA formulation.

Residual moveout-based wave-equation migration velocity analysis in 3-D |

2012-05-10