Compensation for Absorption and Dispersion in Prestack Depth Migration: An Offset-Related Effective Q Approach

Abstract We have developed a prestack depth migration (PSDM) scheme that compensates for absorption and dispersion in the absence of a conventional Q model. The proposed scheme was developed following Kirchhoff approach. Instead of applying a commonly used Q model, we proposed an offset-related effective Q one, which at each spatial location will only and fully determines the local migrated results independent of the effective Qs in other locations. We approximately describe the offset-related effective Q at each spatial point using a quadratic polynomial. The related three parameters are determined during migration using a group of migrated gathers obtained by multiple homogeneous Q migrations. This is completed by solving a three-parameter optimization problem at each spatial point, which maximizes the bandwidth of the stacked spectra of partially and fully stacked local migrated sections inside the window around the point. The proposed approach overcomes the challenge to estimate an interval Q model in depth, as in conventional anelastic PSDM. We applied the resulting effective Q deabsorption PSDM to synthetic 2D data and 3D field data. Higher-resolution imaging results are obtained.