Research On Ocean Bottom Seismometer And Sparker Source Cable Seismic Data Processing Method

With social progress,the development and exploration of new energy are becoming more and more significant.As important clean energy,gas hydrate is one of the critical parts in new energy exploration and development.Today,a growing number of people begin to study the technology of gas hydrate exploration and development.The research shows that most of gas hydrate in China's marine field mainly distributes at the depths of 300 m beneath the seafloor in the range of shallow and high precision exploration.Thus,this paper proposes two kinds of imaging methods on shallow marine seismic exploration as follows:Ocean Bottom Seismometer(OBS)data and seismic imaging technology of sparker source towed.In the process of seismic data acquisition,the advantages of OBS deployed on the seafloor are low interference by the noise of swell and wave with high overall signal to noise ratio(SNR),and of great help to improve seafloor imaging level with the collected shear wave information.However,on account of the high cost of the OBS and the small number of its deployment,such factors led to the narrow range of lighting of the collected seismic data;meanwhile,due to the OBS deployed beneath the seafloor and the source located below the sea level,shot-receiver points were not on the same floor,which made the collected seismic data not meet the law of hyperbola and thus it was impossible to determine the underground velocity model with the method of conventional pick up velocity spectrum.In this paper,on the basis of the existing research results,the narrow range of lighting was solved by multiple imaging technology,shot-receiver points not on the same level by velocity inversion to estimate velocity model and the suitable bin size and the migration parameter by bin optimization and migration parameter to improve the resolution of seismic exploration imaging.Sparker source is the important technology equipment in marine seismic exploration.It is not only environmentally friendly,safe and low-cost,but also has wide frequency bandwidth and high frequency for the collected seismic data that issuitable for the exploration and development of gas hydrate.However,the data collected by sparker source also have some problems,such as irregular wavelet,serious ghost wave interference,complex noise,etc;meanwhile,constrained by acquisition conditions,there are some problems existing in energy out of focus in velocity spectrum for the short towline data of mini offset.In this paper,according to the problems above,complex noise was solved by combined noise attenuation technology;zero-phase deconvolution and predictive deconvolution were used to suppress ghost effect,broaden bandwidth and improve the resolution of seismic exploration.Through repeated tests and the study of imaging methods,the result suggests that the designed data processing flow of the OBS and the sparker is reasonable and is able to achieve seismic section with good imaging effect and clear geological phenomena which have a very well instructive function for marine seismic exploration and processing,and the exploration and development of gas hydrate.