Research On Multiple Wave Suppression Method Of Seabed Seismic Based On Dual-sensor Matching

At present,the main way of offshore oil and gas exploration is marine seismic exploration.In the process of marine seismic exploration,the surface of sea water can be regarded as a good reflection interface.In the process of seismic wave propagation,reflection occurs when passing through the sea water reflector,and multiple waves,also known as ghost waves or reverberations,occur at the receiving end of OBN.Ghost wave is a kind of common interference wave.It follows the first wave and has a delay time.It interferes with the first wave,which confuses the ghost wave and the first wave in the seismic record.Moreover,ghost waves are periodic notch points in the spectrum,which limits the width of the frequency band,and at the same time,some effective low-frequency and high-frequency information is missing.Therefore,it is necessary to remove ghost waves from seismic data.The dual detector acquisition technology locates the pressure detector and the vertical velocity detector in the same position,and carries on the signal acquisition at the same time.Because the polarity of the response of the dual geophone to the upward wave field of seismic wave propagation is the same,but the polarity of the response to the downward wave field is the opposite.Therefore,ghost wave can be effectively suppressed by synthetic processing,thus broadening the frequency band of seismic data.And the resolution has also been improved to some extent.On the basis of the research on the methods of ghost suppression by dual-detector and other broadband acquisition at home and abroad,the formation mechanism of ghost wave and its influence on seismic data are studied,and the basic principle and characteristics of dualdetector are analyzed.Because of the different structure and performance of the two geophones and the influence of the external ocean conditions,the phase,amplitude and frequency of the two geophones are different in the actual situation,so they can not be synthesized directly.So before merging,we need to do a good job of denoising,phase,frequency and amplitude matching and other processing.On This paper,studies the characteristics of double-check data,and concludes that they are different in frequency,phase and amplitude,and further matches the land and water inspection data.In the aspect of frequency matching,because the frequency band of water inspection data is wider than that of land inspection data,and the conventional band-pass filtering will cause the loss of effective signals in land and water inspection records,this paper uses spectral whitening method to widen the frequency band of land inspection records,so as to realize the frequency matching of land and water inspection data.In the aspect of phase matching,this paper introduces the similarity coefficient method based on the conventional phase scanning matching,and verifies the feasibility and validity of this method through numerical simulation and actual data processing.Similarity coefficient method can save a lot of cross-correlation and self-correlation processes,and save a lot of time.In the aspect of amplitude matching,it is not accurate to multiply the land survey data with a fixed coefficient and then add it to the water survey data.Therefore,the matched filtering method is used to process the amplitude matching.Through the above data processing steps of land and water inspection,the matching and merging of double inspection data are realized,and the ghost wave suppression is achieved.The actual data processing results show that the multiples are suppressed well,the phase axis becomes clear,the signal-to-noise ratio of seismic data is improved,and the frequency band is widened.