Institute of Computational Mathematics and Mathematical Geophysics SB RAS

International Conference on Mathematical Methods in Geophysics «MMG-2008»

Akademgorodok, Novosibirsk, Russia, October 13-15, 2008

Abstracts

Mathematical Simulation in Geophysical Problems. Electromagnetic Methods

3D simulation in electromagnetic logging for eccentricity effect estimation

Khitsenko E.V.

Baker Hughes Inc. (Novosibirsk)

The paper describes simulation of electromagnetic field when a logging tool is not centered with a borehole. Medium is supposed to have axial symmetry relative to the borehole and three-dimensionality is only due to the eccentric tool which has low-conductivity mandrel of cylindrical shape. The problem is solved under the assumption that electromagnetic field is quasistationary.

Dimension of a problem is a critical question in 3D finite element modeling. In order to reduce computational costs, the axisymmetric part is separated from the total 3D field. This part is calculated in 2D statement with high accuracy. The remainder is obtained by 3D modeling using a rather coarse grid. Vector basis functions on hexahedral elements are used in 3D modeling and node-based basis functions on rectangular elements are used in 2D modeling.

Examples of electromagnetic field calculations depending on the value of tool eccentricity and their analysis are given. It is shown that the method developed allows us to model responses of the eccentric tool with rather high accuracy and it can be used for eccentricity effect investigation.

Note. Abstracts are published in author's edition

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