Amplitude Preserved Least-squares RTM Gathers

Least-squares reverse time migration (LSRTM) mitigates the illumination problems caused by complex geologic structures, nonuniform acquisition geometry and limited recording apertures. It is theoretically accurate in producing image gathers more suitable for amplitude versus offset (AVO) analysis. We apply image-domain LSRTM in the gather domain with nonstationary matching filters to generate LSRTM gathers with amplitude better preserved. The proposed flow can be applied on both offset and angle gathers with a flat AVO response demigration followed by a remigration. First, we use an acoustic synthetic example to illustrate the idea and verify the results. Then it is applied to a wide-azimuth (WAZ) survey in the Gulf of Mexico.