Research On Seismic Noise Suppression Method Based On Empirical Mode Decomposition

Having high-quality seismic imaging data is the basis for searching for oil and gas resources.However,in the process of obtaining seismic data,both the internal and external environment of the machinery will produce random noise interference,thereby reducing the signal-to-noise ratio of the data and affecting the accuracy of the overlay profile for stratigraphic description.Therefore,based on Empirical Mode Decomposition method and combined with other methods,the suppression of random noise interference in seismic signals is studied.the main content is:The modal aliasing problem of intrinsic mode function(IMF)in Empirical Mode Decomposition(EMD)algorithm is improved.Ensemble Empirical Mode Decomposition(EEMD),Complete Ensemble Empirical Mode Decomposition(CEEMD)and improved Adaptive Complete Ensemble Empirical Mode Decomposition(CEEMDAN)algorithms are proposed respectively.Through the analysis results of decomposition of analog signals,it is considered that the CEEMDAN algorithm is more efficient in the screening process of using EMD method to decompose auxiliary noise and add it to the original signal IMF.While solving the modal mixing problem,the obtained IMF component is more efficient and the residual amount of auxiliary noise is the least.Therefore,this algorithm is used as the basis of the joint method,and two joint methods are proposed to suppress random noise interference.Joint method 1,based on the permutation entropy(PE)of the original signal,the threshold is set to eliminate the ’ abnormal signal ’ in the original time series,and the CEEMDAN algorithm is used to decompose the original signal to obtain several IMF,and the optimal noise reduction model is established to obtain the optimal objective function solution;Joint method 2,using the correlation characteristics of adjacent signals in mutual information entropy method(MIE),the IMF decomposed by CEEMDAN is divided into high and low frequency signals,and the wavelet transform(WT)adaptive threshold method is used to suppress the random noise in the high frequency components of IMF.The experimental results show that the two combined methods have good noise suppression effect.The two combined methods are applied to actual seismic data processing,and the combined method 2 has better effect of suppressing random noise and higher SNR.Using method 2 to suppress noise,the reflection co-phase axis is smoother and more continuous,and the characterization of the structural part is more distinct,which improves the quality of seismic imaging and meets the requirements of seismic data processing as far as possible.