The Research Of Surface Related Multiple Elimination Based On Focal Transform

For Marine seismic data,due to the strong reflection interface formed by the contact between sea water surface and air,multiple wave phenomenon is common and has strong energy,which will interfere with migration imaging of seismic data,greatly affect seismic data processing and interpretation,and ultimately reduce the reliability and accuracy of imaging profile.Multiple elimination is a key and difficult problem in seismic data processing.Therefore,this thesis focuses on the surface related multiple elimination and researches the surface multiple elimination method based on focusing transformation.Surface-related Multiple Elimination(SRME)is a common method for ocean data Multiple Elimination.It consists of two steps: prediction and adaptive reduction.However,adaptive reduction may damage effective wave energy.Therefore,this thesis studies Closed-Loop surface related multiple wave elimination method(Closed-Loop SRME: Cl-SRME),the method takes primary wave and surface operator as inversion parameters and estimates primary wave by full-wave field inversion,which can compensate for the damage of effective wave energy caused by adaptive subtracting when SRME supposes surface related multiple waves,and the stability of the method is verified by model test.However,similar to the SRME method,the CL-SRME method requires seismic data to be full-wave field data,and the lack of seismic trace prevents surface related multiple wave elimination processing,which limits the practical application of this method.In view of the lack of seismic data,this thesis deduced the focus shift interpolation based on the theory of the SRME denoising method,this method by building focus operator,will be focused to transform domain,time domain data thus isolated regional and noise signal,then set up complete denoising threshold to remove noise window area interpolation application,get the full wave field data,The effectiveness of this method is proved by model test.Combined with Cl-SRME method,a closed-loop surface related multiple elimination method(FCL-SRME)based on focusing transformation was proposed,which realized surface multiple elimination under the condition of seismic trace missing.Simulation data and Pluto data tests verified the feasibility and reliability of the method.It provides a new method for multiple wave elimination in the absence of seismic trace,which is of great significance to reservoir description.