Joint Migration Inversion of VSP Walk-Away Lines Offshore Abu Dhabi

Summary One of the main limitations of imaging walk-away VSP (Vertical Seismic Profile) data is the restricted illumination around the borehole, which typically results in reliable imaging only within a narrow, cone-shaped zone. However, by incorporating both primary and multiple reflections from up- and downgoing waves in a Full Wavefield Migration (FWM) process, the imaging area can be significantly extended. When this approach is implemented within a least-squares inversion framework, it also helps suppress crosstalk associated with the multiples. Furthermore, updating the background velocity model through reflection wavefield tomography—resulting in a Joint Migration Inversion (JMI) process —enhances event focusing and further improves image quality. This methodology is demonstrated using VSP data from four walk-away lines acquired offshore Abu Dhabi. In particular, for one of the four lines, where data were collected across five depth segments, the JMI method can drive the inversion toward improved velocity modeling and high-resolution imaging.