基于乘子法的地震波波速和介质密度的多参数稳健反演

Multi-parameter Robust Inversion of Seismic Wave Velocity and Medium Density Based on Multiplier Method

地震波速和介质密度的多参数全波形反演能够充分利用地震数据的运动学和动力学信息,精确重构地下介质模型参数,在地下介质描述与岩性解释中扮演着重要角色。针对地震波多参数全波形反演对初始模型依赖程度高、不同参数之间存在串扰噪声及反演精度不高的缺陷,提出一种基于多尺度策略的多参数乘子法反演框架。将时间域多尺度策略与乘子法相结合,首先进行低频带反演,获取模型空间大尺度信息;随后采用乘子法更新迭代,并将低频带反演结果作为高频带初始模型进行逐频带反演,在每一个尺度下均采用乘子法更新迭代。简单透射模型及1994BP标准地质模型的实验表明:基于多尺度策略的乘子法反演算法具有较好的稳健性与适用性,即使初始模型较差时,仍能获得较好的反演结果,且在不降低地震波速反演精度的同时,提高密度的反演精度。

The seismic multi-parameter full waveform inversion combining wave velocity and medium density can fully utilize the kinematic and dynamic information of seismic data to reconstruct the parameters of underground medium,which plays an important role in geological interpretation of seismic data.However,the multi-parameter full waveform inversion of seismic wave is highly dependent on the initial model,and there is crosstalk noise between different parameters,which restricts the accuracy of the inversion results.Therefore,a multi-parameter multiplier inversion framework was proposed based on the multiscale strategy.Firstly,low-frequency inversion was carried out to obtain large-scale information in the model space.Subsequently,Lagrangian multipliers were introduced to improve the inversion objective function,and the iterative update was completed.Finally,the low-frequency inversion results were used as the initial high-frequency model for band by band inversion.The experiments of the simple transmission model and the 1994BP standard model show that the multiplier inversion algorithm based on multiscale strategy has good robustness and applicability.Even if the initial model is poor,it can still obtain better inversion results,and improve the inversion accuracy of density without reducing the velocity inversion accuracy.