Method Study On Time Domain Registration Of P-and C-Waves

P-wave exploration shows such problems as less information,fewer inversion parameters and poor prediction accuracy facing to complex geological conditions.The Pand C-wave exploration can obtain abundant seismic information.However,there are great differences in data acquisition and subsequent processing between P-and S-waves.Therefore,it is very important to solve the problem of time domain registration in P-and C-waves seismic profiles.This paper starts with the generation principle of P-and C-waves,the time-distance equation,and analyses the dynamic and kinematic characteristic of them.Then,the effects of velocity ratio,amplitude,frequency and waveform on the matching are studied.The method of P-and C-waves matching in this paper is DTW(dynamic time warping)algorithm,which stemed from DP(dynamic programming)method.DTW algorithm is commonly used in speech sequence matching research.It mainly includes four steps: alignment error,accumulation error,backtracking optimal path and sequence matching.It will be accompanied by some artificial constraints to improve the optimal degree of the solution.Compared with conventional methods,DTW algorithm is applied to the actual seismic data and synthetic data to verify.It is found that the correlation coefficient after matching has been significantly improved,matching results are optimized,the velocity ratio of P-and S-waves can be calculated from time shifts,and then the velocity ratio model of underground media can be obtained.DTW with rough sampling intervals(SDTW,smooth dynamic time warping)is robust in noisy sampling sequence.The DIW(dynamic image warping)algorithm accumulates the alignment errors in DTW algorithm,and smooth the corrugation of time shifts and velocity ratio of P-and S-waves.Finally,the calculation results are further smoothed by SDIW(smooth dynamic image warping)based on method improvement.It is found that each smoothing module needs reasonable settings in order to achieve the balance between accuracy and smoothness,and give full play to the advantages of the above methods,so as to achieve the most practical results.