The complex structural area in the piedmont zone has abundant oil and gas resources,but the low signal-to-noise ratio(SNR)of the data and the difficulty of velocity modelling bring challenges to accurate seismic imaging for the piedmont zone.Based on the data from the Haitangpu area in the piedmont zone of Longmen Mountain,this paper presents an applied research-based work on prestack depth-domain seismic imaging processing,especially with respect to prestack noise suppression and pres-tack depth migration velocity modeling.This work includes two procedures:①protection of low-frequency weak signals,and ② op-timization of prestack depth migration velocity modeling process.The secondary signal-to-noise separation technique is adopted to perform a secondary signal-to-noise separation on effective signals in noise recording,so as to protect the low-frequency weak sig-nals to the maximum extent.To optimize the prestack depth migration velocity modeling process,the situation that input gather and offset input gather share a common gather in traditional depth-domain velocity field update is optimized by five-dimensional data regularization of input gather driving the velocity field update to improve its SNR.Then,based on geosteering,the interface with strong reflection but missing velocity information is finely characterized,and the depth-domain near-surface velocity model is combined with joint tomographic inversion to establish a depth-domain velocity field with geological model constraints.After an ac-curate velocity model is obtained,the migration input gather and migration method are modified,that is,the gather before five-di-mensional data regularization is taken as the input gather,and the full-azimuth angle-domain prestack depth migration as the final migration imaging technique.Application of this method to the Haitangpu area demonstrated a significantly improved seismic ima-ging accuracy,a high SNR in the final prestack depth migration imaging results,and a rational migration positioning.This provides a valuable reference for depth-domain seismic imaging processing to further promote the exploration and development in the area.
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