地球物理联合反演新框架研究

A new framework for geophysical joint inversion

在以往联合反演研究中,人们往往关注某些关键技术,很少关注联合反演的框架;此外,精细联合反演的初始建模人为性较强,反演结果对初始模型依赖较大。对于这些不足,提出了联合反演研究的新框架,即"多次建模,综合约束,分步反演"的策略。在此框架里,基于多种约束条件,初始建模和联合反演是阶段式实现的。以大地电磁(MT)和地震联合反演为例对新框架进行了诠释,并设计了典型的玄武岩模型来检验新框架。模型试验中,MT和地震方法均表现出了各自的局限性,在联合反演新框架指导下,通过电阻率和速度联合反演,大地电磁和地震两种方法取长补短,选取最常见的初始模型成功解决了玄武岩下伏地层形态不清的问题。与以往要求精细的初始模型的联合反演相比,新框架可以明显降低初始建模过程中人为因素的影响,在一定程度上降低了反演结果对初始模型的依赖程度。

For previous geophysical joint inversion research,geophysicists'concerns usually are some key techniques rather than its framework.In addition,an initial model building for rigorous joint inversions is strongly dependent on artificial judgments,and results considerably rely on the initial model.Therefore,we provide a new framework for geophysical joint inversion,which is called as'multiple modeling,integrated constraints,and step-by-step inversion'.In this framwork,model buildings and joint inversions are realized in stages based on multiple types of constraints.We take a joint inversion of magnetotelluric(MT)and seismic data for example to illustrate the new framework,and design a typical basalt model to test the new framework.MT and seismic methods show their limitations in the single model test.Then,we apply the joint inversion to complement each other based on the new framework,and study the distribution of strata under basalt using a common initial model.Comparing with the formerly joint inversion needing a detailed initial model,the new method can reduce the influence of human factors during the initial model building,and lower the reliance of the result on the initial model to some extent.