Study On Wave-equation Active And Passive Interferometry Subsurface Imaging

Geophysical interferometry imaging technology is an important research content in the field of geophysical data processing and target imaging.Interferometry technology is based on the derivation of Green's function formula,and signal processing methods such as cross-correlation,cross-coherence and deconvolution are adopted to process geophysical signals in order to enhance target reflection,suppress noise interferometry and reconstruct virtual source data.For seismic data from active sources such as pulse source,interferometry technology can be used to suppress background noise and enhance the application of target response signal or observation data type conversion.For geophysical data of passive sources such as noise source and transient source,interferometry technology can be used to restore and reconstruct virtual source data,so as to realize target imaging and medium change monitoring in strong interferometry environment.Interferometry imaging technology has a wide application prospect in shallow underground space detection,natural seismic noise imaging and mineral resources reservoir monitoring.In this paper,we are aiming at active and passive source interferometric subsurface imaging technology,the basic principles of interferometry technology based on three typical signal sources(pulse source,transient source and noise source)are derived in detail.The basic mathematical principles of interferometry technology are derived according to the classification of sound wave,elastic wave and electromagnetic wave which are widely used in geophysics.The basic mathematical principles of different signal sources under different physical fields such as seismic wave field and electromagnetic wave field are summarized in detail.On this basis,the finite difference numerical calculation method of acoustic wave,elastic wave and electromagnetic wave is applied to the numerical simulation of interferometry imaging technology and the test of actual data.Finally,the application of four typical wave equation active and passive source interferometry imaging techniques is introduced.The first method is seismic velocity tomography based on 4-D interferometry imaging technology.Instead of inverting absolute traveltimes,differential traveltimes are calculated by interferometry technology.Based on the wave equation velocity tomography method,we can conduct interferometry velocity inversion,and the small-scale time-lapse seismic velocity is obtained by differential traveltimes.The second method is research on the application of interferometry interpolation of marine active seismic data based on steady-state interferometry technology,which improves the problem of data loss caused by excessive offset in the process of marine seismic data acquisition.The third method is active source surface wave inversion imaging based on interferometry technology,the virtual seismic data is reconstructed by interferometry technology through a few shots,and the inversion results similar to conventional acquisition,which greatly improves the calculation efficiency.Finally,the method of passive source electromagnetic interferometry in well radar reservoir monitoring is proposed,the typical reservoirs such as geothermy are monitored by interferometry imaging with well radar technology by constructing high-frequency electromagnetic noise signal source.Through different model tests,we can get high precision imaging results of reservoir structure by applied passive source interferometry technology in well radar monitoring.In summary,in this paper,we summarize the basic mathematical principles of interferometry technology of geophysics,such as seismic and electromagnetic,and test the application of interferometry technology with the finite difference method systematically.The application of four typical active and passive interferometry techniques prove that the wave equation interferometry imaging technique can be applied to active and passive source seismic and well radar data interpolation,time shift monitoring and velocity imaging effectively.The research of this paper provides basic theoretical basis and typical application for the development of interferometry technology in geophysics.The research results of this paper are of important significance to expand and improve the application of interferometry technology in active and passive source technology of geophysics.