弹性波逆时偏移的角度域共成像点道集提取方法

Angle-domain common-image gather extraction based on elastic reverse time migration

对于多分量地震勘探,由于介质中纵、横波的耦合作用,多波角道集存在能量串扰和低波数噪声干扰等问题。针对横波Poynting矢量构建过程中存在的应力串扰问题,基于解耦延拓方程及伪横波应力构建方法,对质点振动速度和应力进行解耦,实现了无能量串扰的纵波和横波Poynting矢量构建;在基于Poynting矢量提取PP波反射角和PS波反射角的基础上,提出了基于弹性逆时偏移的PP波和PS波角道集提取方法;针对PP波角度域共成像点道集存在的低波数噪声干扰问题,提出了角度域共成像点道集的角度衰减叠加策略,提高了偏移成像精度。应用模型数据验证了方法的正确性。

Due to the coupling effect of P-and S-waves in the medium,multi-wave angle-domain common-image gathers(ADCIGs)encounter the problems such as energy crosstalk and low wavenumber noise in multicomponent seismic exploration.To solve the stress crosstalk problem in the construction of the Poynting vector of S-waves,this study uses the decoupled wave equation and pseudo-Swave stress construction method to decouple the particle vibration velocity and stress,and the Poynting vectors of the P-and S-waves are constructed without energy crosstalk.Then,the PPwave and PS-wave reflected angles are extracted given the Poynting vectors.On this basis,this paper proposes the PP-wave and PS-wave ADCIG extraction method based on the elastic reverse time migration(ERTM).Considering the low wavenumber noise in PP-wave ADCIGs,an angle attenuation superposition strategy for ADCIGs is proposed to improve the migration imaging accuracy.The model test verifies the correctness of the method.