Comparison Between Grid Tomography and Horizon-based Tomography in Prestack Depth Migration (PSDM)

Authors : Selin Ceren, Yeliz İşcan Alp, Hakan Alp

Pages : 65-76

View : 95 | Download : 59

Publication Date : 2025-08-29

Article Type : Research Paper

Abstract :In this study, routine and non-routine data processing steps were applied to multichannel seismic data. Prestack Depth Migration (PSDM), previously a non-routine process, has become routine in many seismic explorations due to advancements in hardware and software capabilities. In geologically and tectonically complex study areas, depth migration is essential to obtain accurate subsurface depth images. Therefore, after deriving the initial interval velocity depth section, both post-stack and prestack depth migration techniques were applied to improve subsurface imaging accuracy. Non-flatness in common depth point (CDP) gathers from PSDM indicated the need to update the interval velocity model in depth. Grid tomography and horizon-based tomography were used to refine the interval velocity depth section. PSDM was then reapplied using the updated velocity model. These steps were iteratively repeated until the CDP gathers were flattened. Grid tomography was applied twice to update the interval velocity depth section. However, analysis of the depth section from the second PSDM iteration (using grid tomography-derived velocities) showed that deeper reflections remained poorly resolved. Consequently, five additional PSDM iterations were performed with horizon-based tomography-updated velocities, resulting in significantly improved imaging of both shallow layers and the basement. Finally, depth sections from post-stack depth migration, initial PSDM, and subsequent PSDM iterations were compared to highlight the critical role of PSDM in achieving a geologically realistic model.
Keywords : Yığma Öncesi Derinlik Migrasyonu, grid tomografi, tabaka bazlı tomografi, sismik veri işlem

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