Research on Spectral Whitening Method of Seismic While Drilling Ahead Detection Signals Based on VMD

Seismic source of seismic while drilling ahead detection is consistent and uncontrollable,which requires to convert continuity source records into equivalent pulse source records by cross-correlation to obtain effective reflected signals.However,as the signal often contain dominant frequencies with narrow frequency band and relatively large amplitude,so the method of cross-correlation processing will lead to serious interference.This article proposes to apply the Hilbert spectral whitening method which based on VMD(variational mode decomposition) to signals of seismic while drilling ahead detection.Firstly,this method decomposes the seismic signals into multiple IMF(intrinsic mode function) with VMD,then the IMF is decomposed by Hilbert transform,finally,the Hilbert spectrum is whitened by a whitening filter.The numerical simulation results show that the Hilbert spectrum whitening method which based on VMD can not only ensure well consistency of signals for each trace,but also equalize the different frequency components of signals,effectively suppress the false lineups in the cross-correlation records,and accelerate the attenuation of the sidelobe of the main peak.The method proposed in the article is applied to the actual data of a tunnel in Yangzhuang coal mine,Huaibei,Anhui province,and the fault structure in front of the tunnel face is successfully detected,which shows that the method is very practical.