Subsalt Scans Using Wave Equation based Focusing Analysis and Poststack Modeling

We have developed a new methodology to produce a best focused zero-offset image, even though the migration velocity model has errors. In this methodology, first we generate Common Focusing Error (CFE) images using wave equation based prestack migration and applying zero-time as well as non-zero-time imaging conditions. Then a semi-automatic procedure is applied to pick the focusing error (DT) field, and the picked DT field is used to select the best focused image from the CFE images. To produce an accurately positioned and well focused zero-offset image, we separate the prestack focusing effect from the poststack focusing effect, by performing poststack demigration followed by DT compensated poststack remigration.