3D DEPTH MIGRATION BY ROTATED MCCLELLAN FILTERS

The application of McClellan transformations considerably reduces the computational cost of 3D wavefield depth extrapolation by explicit con volutional methods. The accuracy of migration methods based on McClell an transformation depends on how well the transformation filter (cos \ k\) is approximated; errors in this approximation cause anisotropy in the extrapolation operator and frequency dispersion in the migrated re sults. The anisotropy can be greatly reduced by rotating the approxima te filter by 45 degrees and averaging the rotated filter with the orig inal filter. The application of the rotated filter yields a migration method that correctly images very steep dips, with little or no additi onal computational cost. McClellan migration with the improved circula r response enhances the imaging of synthetic and real data.