Research On Deghosting Method For OBC

With the deepening of exploration of marine oil and gas resources in China,marine broadband seismic exploration technology has been greatly developed.In marine seismic exploration,the interface between seawater and air is a strong wave impedance interface with a reflection coefficient of-0.8 to-1.Upward waves in marine seismic exploration will continue to reflect downward after exposure to the surface of the sea,and are received by the detector,called ghost waves.The existence of ghost waves makes the ocean seismic data appear trapped,which seriously affects the effective bandwidth of seismic data and reduces the quality of seismic data.Repressing ghost waves,compensating for trapping points,and widening seismic bands are the key and difficult points in the process of marine broadband seismic processing.The ocean bottom cable technology is the main marine broadband seismic exploration technology in shallow waters.The data ghost wave is seriously developed,and it is urgent to study the special ghost wave suppression method and technology.This paper has carried out research works.Through literature review and investigation,the existing marine seismic broadband exploration technology and the deghosting method were dissected and analyzed.Based on the formation mechanism of ghost waves,the frequency and polarity characteristics of ghost waves are analyzed by forward modeling.The influence of different cable depths on the spectrum of seismic data is also discussed.For the oceanbottom cable exploration technology,we analyze the time difference between the primary wave and the ghost wave propagation under plane wave conditions.Introducing the Radon transform and designing the Radon transform algorithm for suppressing ghost waves.We used the model and actual data for trial processing,improved the stability of the algorithm module,and optimized the parameter range.Finally,the method was applied to the actual ocean bottom cable data in the Bohai Bay Basin,which proves the effectiveness and feasibility of the proposed method.The analysis of seismic profiles and spectra before and after suppression of ghost waves show that this method can suppress ghost waves very well and false events caused by the ghosts is eliminated,indicating that the method has a good application prospect.