Research On The Deghosting Method For Dual-sensor Technique In Marine Seismic Explortion

In marine seismic exploration,the sea surface is a good reflection interface.Ghost appears during the seismic wave propagation process because of the sea surface reflection.Ghost is an usual kind of strong reflection which is followed with the primary reflection after a delay time,it intervenes with the primary reflection each other,their seismic events are mixed together on the record.Moreover,as for effects of ghost,there are periodic notches in the spectrum of seismic data and the frequency bandwidth is limited which leads to a part of low frequency and high frequency information is missing.Therefore,it is necessary to remove ghost reflection from seismic data.Dual-sensor acquisition technology puts both hydrophone and geophone at the same location on cable,because their responses to seismic wave field are different,they have the same polarity for the up-going wave field while the opposite polarity for the down-going wave field.So combining dual-sensor data can remove ghost,extend the frequency bandwidth and improve the resolution of seismic data.Based on the research of dual-sensor and other broadband marine technology,this paper studies about ghost formation mechanism and its influence on spectrum,and analyzes both sensors’ working principle and their characteristics.In practice,dual-sensor cannot be directly combined as they are different about SNR,frequency,amplitude and other aspects because of influences of their self-performance and external conditions,so it needed to remove noise and match the phase,frequency and amplitude before combining.This paper uses matching filter method for dual-sensor summation on the basis of characteristics of dual-sensor.And this paper also studies ODG and cross-ghosting method about dual-sensor combining,they all achieve the purpose of removing ghost by ricker wavelet,numerical simulation and actual profile data processing.This paper presents a new dual-sensor summation methods for cross-ghosting based on F-K domain which obtains a calibration factor by matched filter.It makes two sensors’ record the same form by hydrophone record convoluted with geophone ghost and geophone record convoluted with hydrophone ghost.Both the simulated and practical data processing have removed ghost and the frequency band is broadened with disappear of notches and its signal-to-noise ratio is higher.These all above verify the validity of this method.