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Anisotropy Sensitivity Analysis with 2.5D CSEM Inversion of Broadside DataNormal access

Authors: L. Masnaghetti, F. Ceci and A. Lovatini
Event name: 73rd EAGE Conference and Exhibition incorporating SPE EUROPEC 2011
Session: Electromagnetic Methods II
Publication date: 23 May 2011
DOI: 10.3997/2214-4609.20149046
Organisations: SPE, EAGE
Language: English
Info: Extended abstract, PDF ( 764.04Kb )
Price: € 20

Resistivity well logs and practical experience indicate that the resistivity of the subsurface can be characterized by a significant degree of electrical anisotropy. In this paper, we analyze the possibility to resolve electrical anisotropy with controlled-source electromagnetics (CSEM), by comparing the results of 2.5D inversions of synthetic datasets with different acquisition geometries. We also present the results of the application of the 2.5D inversion scheme augmented with broadside data used for the study on a real CSEM dataset acquired offshore Brazil. The study consists of a comparison of the results of anisotropic inversion with three different survey geometries, using a 2.5D forward modeling and inversion scheme that allows us to simulate data in broadside configuration. The analysis shows that offline data must be incorporated in the inversion process to fully recover the horizontal resistivity component and that the roles of transmitter and receivers can be exchanged without losing the capability to constrain anisotropy during inversion if the 2D assumption is fulfilled. The application of the inversion scheme to real data demonstrates how 2.5D methods can be extended with the inclusion of broadside data to provide additional tools for the inversion and interpretation workflow.

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