Scholarly record

COMPARISON BETWEEN FREQUENCY-DOMAIN HELICOPTER ELECTROMAGNETIC DATA INVERSION RESULTS BASED ON NUMERICAL SOLUTION OF FAST HANKEL COEFFICIENTS AND LAPLACE’S METHODS

D. Rajabi, A. A. Amiri, A. Kamkar-Rouhani, A. Moradzadeh

Abstract

Nowadays, airborne electromagnetic methods are widely used to investigate subsurface areas. One of these methods is helicopter electromagnetic method. The basis of inverse modeling of frequency-domain HEM data is to solve Mundry’s integral numerically. Various methods have been invented for numerical solution of this integral, such as Laplace transform, fast Hankel coefficients and Jacobian methods. To analyze helicopter electromagnetic data, we need inverse programs which can assist us to achieve the best or accurate interpretation results. Considering that forward modeling program results can improve or degrade the accuracy of an inversion program, thus, we need to concentrate of the preliminary model results. The purpose of this paper is to present and compare the algorithms based on numerical solution of fast Hankel coefficients and analytical Laplace’s methods, and then investigation of the advantages and disadvantages of each method. For this, the results obtained from these algorithms have been investigated using inverse modeling codes. In this regard, we have found that forward modeling program using Laplace’s method is much faster than Hankel numerical solution method though writing a code based on Laplace method for this purpose is more difficult than the Hankel method. Also, by accurate selection of relevant parameters for the media, we can see that the final results quite approach to initial model parameters.

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