Application Of Gaussian Beam Prestack Depth Migration In Rugged Seabed

In response to the sudden increase in water depth of the rugged seabed in deep waters,strong seafloor ups and downs,and repeated changes in the inclination of the seabed,seismic data will show chaotic reflections,obvious multiple waves,severely developed side waves,basement planes even unable to image,and sag structures,The low signal-to-noise ratio of the middle and deep layers is the problem of the degradation of seismic data imaging quality.This paper first uses the Gaussian beam prestack depth migration imaging method to analyze and discuss the imaging effect under rugged seabed conditions in deep water.By using different velocity models,the method is proved to be reasonable.Secondly,three factors that affect the effect of Gaussian beam shift are discussed.Aiming at the discontinuity of the seawater velocity model interface,the velocity model is locally smoothed by selecting an appropriate smooth velocity model method,and the smoothed velocity model is used to improve the migration results as a whole.In view of the lack of imaging data of the steep dip angle structure at the boundary of the sea speed model,the wavefront construction method is used to carry out ray tracing to simulate the seismic wave field under the rugged seabed and analyze the kinematic characteristics of the seismic wave in the deep water area.By improving the design of the seismic data acquisition and observation system and adopting a large offset for target imaging,all fine structure imaging can be perfected.The energy distribution of seismic illumination is used to analyze the energy illumination of the rugged seabed to find the reason for the poor imaging effect of the middle and deep layers,select the appropriate and effective shot point information,and perform migration imaging to eliminate the false structure of the middle and deep layers.Finally,the feasibility of the method is verified through actual ocean data.