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Two-dimensional Joint Inversion Of Gravity,Magnetic And Resistivity Data With Cross-gradient Constraints

Posted on:2016-12-10Degree:MasterType:Thesis
Country:ChinaCandidate:F TangFull Text:PDF
GTID:2180330461995661Subject:Earth Exploration and Information Technology
Abstract/Summary:PDF Full Text Request
It is now common practice to perform collocated gravity, magnetic and electrical resistivity surveys that complement each other in the search for more accurate characterization of the subsurface in many field situations. Models obtained by separate inversions of respective data sets are not in good accord considering of the ambiguity of inversion, the disadvantages and limitations of each method. If we consider the assumption that different physical properties are similar in structural features, for instance, gravity, magnetic and electrical resistivity mentioned in this paper have the same structures, a bettermodel can be obtained by joint inversion scheme incorporating the cross-gradient term which consists of different model gradients into objective function, Our algorithm aims to develop a consistent structural model for remnant density, magnetic susceptibility and electrical resistivity. We used the analytical method to calculate gravity and magnetic anomaly, and finite element method to solve resistivity forward problem. We obtain the gravity, magnetic and resistivity model by smoothest model constraints with regularization method.Meanwhile, we introduced the logarithm barrier method to constrain the density contrast and magnetic susceptibility, in order to keep the properties positive. We can draw the conclusion that results from joint inversion are indeed superior to those from separate inversions in values and shapes after applying this algorithm to several theoretical models.Therefore, the 2-D joint inversion scheme based on cross-gradient constraints is verified to be correct and valid.
Keywords/Search Tags:density contrast, Magnetic susceptibility, electrical resistivity, Cross-gradient, Joint inversion
PDF Full Text Request
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