Combination Of Direct Current Resistivity Data From Multiple Electrode Arrays And Its Joint Inversion With Gravity Data

Electrical resistivity tomography（ERT）is increasingly used in near-surface fields.However,the highly heterogeneous shallow medium and limitation of the measurement scale often affect the accuracy of the electrical resistivity inversion imaging,especially involving complex and multi-scale problems of fluid transport and transformation.To make full use of geophysical data sets,reduce the non-uniqueness of inversion,and enhance the ability to characterize heterogeneous shallow media,this paper conduct research on the joint inversion of multiple single-attribute（resistivity）datasets from different electrode arrays and the joint inversion of electrical resistivity and gravity data with spanning physical properties.In the context of multiple single-attribute（resistivity）datasets,we first introduce the weighted combined inversion algorithm based on the Jacobian matrix and apply it to theoretical model tests and a field example of detecting the noble tomb of the Yue Kingdom in Xiaomantou Hill,Shaoxing City,respectively.We find that weighted combined inversion alleviates the poor spatial resolution of individual inversion but still suffers from the domination effect of the dominant dataset.On this basis,the coupling strategy with intrinsic parameter relationship is proposed and tested on theoretical hydrological models and the field example.The results reveal that the joint inversion with the intrinsic parameter relationship coupling can obtain better geoelectric models,enhancing and mitigating the spatial resolution and domination effects of dominant DC resistivity datasets,respectively.Furthermore,to study the highly heterogeneous fluid-CO₂ migration,the cross-gradient joint inversion of large-scale resistivity and gravity data are utilized to supplement additional information on mass distribution and to identify the relatively high-resistivity characteristics of gas or proto-rock origin.The results reveal conductive anomalies associated with the fluid-rich Po?átky-Plesnáfault zone（PPFZ）and its subsidiary structures beneath the Hartou?ov mofette field（HMF）,including fluid-CO₂channels and newfound fracture pathways of vertical fluids flow.The characterization of fluid-CO₂ migration shows the superiority of the joint inversion over individual inversion in recovering sedimentary sequence,strata thickness,and resistivity amplitude,and it also demonstrates the feasibility of cross-attribute joint inversion to enhance resistivity structure.