Pre-stack depth migration of seismic reflection data in the Iskenderun Bay

The Gulf of İskenderun, located in the northeast of the Eastern Mediterranean, is a tectonically active region. The tectonic regimes around the Eastern Mediterranean are continental collision along the Bitlis-Zagros suture zone in the east, subduction zone between the African and Anatolian plates along the Cyprus arc and the Hellenic arc in the south, and the westward escape of the Anatolian plate along two major strike-slip faults. In this thesis, 4 profile multi-channel seismic reflection data collected by the Turkish Petroleum Corporation (TPAO) in the Gulf of İskenderun in 1989 were used. The seismic data were processed using Emerson-Paradigm Echos & GeoDepth software and by applying 2D Kirchhoff pre-stack depth migration, depth sections of the region were obtained for the first time. Both routine and non-routine data processing steps were applied to the data. Routine data processing steps are data loading, geometry definition, editing and muting, band-pass filtering, static correction, predictive deconvolution, f-k filter, CDP sorting, F-K filter ZMULT module, velocity analysis and stacking. The non-routine data processing step is pre-stack depth migration (PSDM). Pre-stack where the subsurface has complex tectonic features (faulting, folding, salt domes). The PSDM method uses an interval velocity model. The interval velocity model allows ray bending at layer boundaries using real ray paths. In this study, initial depth sections were obtained after applying pre-stack depth migration (PSDM) with the initial interval velocity model for each seismic line. Non-horizontality was observed in the CDP groups obtained from the PSDM application with the initial interval velocity model and grid tomography and horizon-based tomography methods were used to eliminate this error. Following tomography, PSDM was re-applied with the updated interval velocity model, and the data processing steps were repeated iteratively until the CDP groups became completely horizontal. The aim of the study is to obtain depth sections that provide the most accurate approach to the subsurface in Iskenderun Bay by applying pre stack depth migration and to explain how the grid tomography and horizon-based tomography methods used in pre-stack depth migration yield results in imaging shallow and deep layers, faults and foldings by making comparisons between the obtained sections.