Progress Report on Multiple Elimination and Least Squares Migration of VSP Data

I predict VSP free-surface multiples and subtract them from VSP data, and then apply least squares migration (LSM) to the VSP data. The LSM image contains noticeably fewer artifacts associated with the aquisition footprints than the standard VSP image. The freesurface multiple artifact is considerably diminished in the demultipled data, and the migration image with demultiple VSP data has fewer artifact than with the original VSP data. The cost of least squares migration is negligible for VSP data imaging and LSM can significantly reduce its attendant acquisition footprint; and so these results are tentatively suggesting that LSM of VSP data should be entertained as a standard VSP processing method. Further work with both field data and synthetic data will be carried out to test this assertion. Sensitivity tests with repect to the migration velocity model will also be carried out.