Research On Borehole Seismic P Wave And S Wave Separation And Seismic Imaging Method

Compared with conventional seismic data,borehole seismic data has the advantages of high precision and high resolution,and borehole seismic data can clearly display the geological structure and petrophysicals near the well.By performing more precise imaging of geological structure near the borehole,it is a good supplement to conventional seismic data.As the targets for oil and gas E&D become more and more complex,it is necessary to research borehole seismic data processing.At present,borehole seismic exploration mainly uses primary wave source,and a large number of converted shear waves will be generated during the propagation.For borehole seismic data with complex wave fields,extracting pure P wave and S wavefield can improve the accuracy of seismic imaging.Therefore,the processing and imaging of P wave and S wave from borehole seismic data are researched.This paper focuses on the separation of P wave and S wave and imaging in borehole seismic data processing.The characteristics of borehole seismic observation system are analyzed,base on which,the elasic wave equation forward algorithm is designed,and according to the forward results,the borehole seismic wave field is analyzed.The high-resolution Radon transform polarization filtering method is researched base on the characteristics of borehole seismic propagation,and the P wave and S wave are separated in the τ-p domain.To obtain pure P wave and S wave,an angle filtering method is proposed,which apply the difference of propagation angles to separate wave filed when the seismic wave arriving at the geophone.The reverse time migration is applied to the borehole seismic,in which the normalized crosscorrelation imaging condition is adopted,and the generation mechanism of low-frequency noise is analyzed.During the cross-correlation imaging process,the Laplacian filter is used to suppress low-frequency noise,and the imaging result is optimized.The model and actual data processing results show that the method used in this paper can effectively separate the P wave and the S wave.The reverse time migration and imaging technology can pefectly restore the real condition of underground structure,and produce high resolution and high signal-to-noise ratio imaging results.