Compensation for absorption and dispersion in prestack migration: An effective Q approach

摘要

We have developed a migration scheme that can compensate absorption and dispersion caused by intrinsic attenuation in subsurface media. The scheme was developed by adapting prestack time migration (PSTM) in the frequency domain. Instead of applying a commonly used Q factor, we devised an effective Q parameter to compensate absorption and dispersion. The effective Q determines the frequencydependent traveltime and amplitude at one imaging location by only one value. As a result, the effective Q can be estimated by scanning technology. We designed an index that can remove the effects of interferences of the reflections resulting from stacked thin layers in extracting the effective Q parameter from scanning results. The proposed scheme can thus determine an effective Q model using surface seismic data during migration. Stabilization is achieved by introducing a smooth, maximum-limited gain function that matches the exact amplitude compensation factor when it is less than the user-specified gain limit. The proposed scheme can be incorporated into conventional PSTM workflow. Synthetic and field data sets were used to test the proposed deabsorption PSTM. Higher-resolution imaging results are obtained.