Elastic reverse time migration based on P/S wave-mode decoupling and wavefield decomposition
The noise in the Elastic Wave Reverse Time Migration(ERTM)imaging mainly comes from the crosstalk noise generated by the coupling of the P-wave and S-wave fields and the low frequency noise generated by the cross-correlation imaging of the co-path source vector wavefield and receiver vector wavefield.Noise can affect reverse time migration.This paper studies migration noise suppression in ERTM.Firstly,the elastic wave field numerical simulation is realized by using high precision staggered mesh finite difference method based on the first-order velocity-stress equations.Then based on the time domain vector separation equation,the pure P-wave and S-wave fields are extracted to effectively suppress crosstalk noise in the imaging profile.And then on the basis of the decoupling of the P-wave and S-wave,based on the optical flow vector,the traveling wave separation in different directions of the source wavefield and the receiver wavefield is realized,and the cross-correlation imaging is carried out.The sixteen reference profiles are correlation weighted superposition to effectively suppress the low wave number noise,and finally the elastic wave reverse time migration imaging profile based on elastic wave-mode separation and optical flow vector wavefield decomposition is obtained.The calculation of theoretical model data shows that the separation of the wave field can be achieved well based on the time domain vector separation equation,and the amplitude and phase of the separated wave field will not be distorted.The RTM profile based on the decoupling of source wavefield and receiver wavefield can effectively suppress the crosstalk noise and improve the profile quality.The reverse time migration method based on the optical flow vector wavefield decomposition can realize the traveling wave separation of the source wavefield and the receiver wavefield more accurately and stably.The reverse time migration profile obtained by this method,the continuity of the in-phase axis is further improved,the profile quality is improved,and high precision imaging is realized.
Elastic Wave Reverse Time Migration(ERTM)P/S wave-mode decouplingOptical flow vectorWavefield decomposition
万方数据
维普
