Study On Synchronous Geophysical Joint Inversion

The joint inversion technique can effectively improve the quality and credibility of the inversion results.However,due to the asynchronous correction of data errors and model updates during the inversion process,the synchronous joint inversion,which embodies the idea of joint inversion more,is often not as effective as the sequential joint inversion in practical applications.To solve this problem,this paper conducts research on synchronous joint inversion.Firstly,the synchronous joint inversion model is analyzed and summarized,and the joint inversion is divided into three models: single-dataset inversion multi-parameter(SJIMS),multi-dataset inversion of the same parameter(SJISM),and multi-dataset inversion of multiple parameters(SJIMM)from the perspective of dataset and inversion physical properties.On the basis of regularization technology,the objective function of synchronous joint inversion is uniformly defined,the key problems existing in synchronous joint inversion are analyzed,and the synchronization technology of synchronous joint inversion is studied.For the dataset balance problem of SJIMS and SJIMM inversion models,a dataset balancing scheme based on the normalization of the number of different datasets is proposed.For SJISM and SJIMM inversion models,the influence of model constraint scale factor on inversion caused by large variation of parameter value intervals and different data sensitivity is discussed.The combined inversion resistivity and permittivity of radio frequency geodetic electromagnetism(RMT),synchronous combined inversion resistivity and conductivity of AMT measured data,synchronous combined inversion resistivity and conductivity of audio geodetic electromagnetism(AMT)and DC resistivity(DCR),DCR and seismic traveltime imaging were used as examples.In addition,the synchronous joint inversion research based on ADMM distribution optimization method and FCM clustering joint constraint algorithm is further carried out,and a selection scheme for FCM joint constraint weight increases with the number of iterations is proposed.Theoretical analysis and model examples show that the balance between datasets,the balance of inversion parameters by orders of magnitude,and the balance of model constraints have serious effects on synchronous joint inversion.The proposed balanced scheme of data fitting term and model constraint term equilibrium joint inversion scheme is effective and feasible.In addition,the known prior physical properties are introduced into the joint inversion objective function by additional ADMM distribution optimization method and FCM clustering joint constraint,which can improve the quality of the inversion model to varying degrees.A selection scheme in which the weight of FCM joint constraint increases with the number of iterations is proposed,which can effectively avoid the problem of excessive FCM joint constraint in the early stage of inversion.