Study On Seismic Data Rugged Surface Migration Imaging

The southeastern region of China is mainly mountainous and hilly,with great difference in surface elevation and outcropping of rock formations.The velocity of complex subsurface structure changes dramatically,the formation dip angle is large,and the velocity modeling is difficult.The inaccurate velocity will bring adverse effects on the subsequent nmo,residual statics and other processing,and greatly reduce the accuracy of migration imaging.The near-surface velocity model can be accurately solved by using the refraction wave or tomographic static correction based on the first arrival.The surface offset trace set can be extracted by attribute migration,which can be used to update the velocity,improve the accuracy of the velocity model,and facilitate the fluctuation surface migration of seismic data.In this paper,a theoretical model is used to analyze the influence of the near-surface velocity inaccuracy of the terraced monoclinic model on the subsequent migration imaging,and the influence of the selection of different datum levels on the imaging in the static correction of the complex salt dome model.In the migration imaging,the calculation strategy of combining static correction processing with undulating surface migration is adopted to process the model data and the actual data of the mountain.The analysis of the treatment results shows that:1.In the model data test with accurate velocity modeling,the true surface imaging without static correction has the highest imaging accuracy;2.In the near surface modeling complex,difficult mountain in actual data experiment,near-surface velocity model is difficult to accurately calculate,static correction processing does not meet the theoretical assumptions,then at the right on the datum velocity modeling and migration imaging surface model can be simplified,reduce the influence of near surface factors,and get better imaging results;3.It is an effective method to improve the accuracy of velocity modeling to update the velocity of common imaging point trace set in offset domain,Multiple iterations can effectively reduce the remaining velocity;4.Differences between specific true surface velocity changes and established velocity models should be analyzed.At the same time,tomographic inversion is used to improve the accuracy of velocity model;In general,depth migration of undulating surface can play an important role in processing seismic data with complex near-surface conditions,and its imaging effect is obviously better than other migration methods.