Nonlinear Inversion in Induction Logging Using the Modified Gradient Method

摘要

A method for reconstructing the electrical conductivity profile of a contrastingobject in an embedding medium is applied to the problem of induction logging as is known in the oil industry. The conductivity of the formation and the unknown electromagnetic fields are simultaneously reconstructed in an iterative way using a conjugate-gradient type of algorithm. In the algorithm it is assumed that the conductivity is a positive quantity. This fact, together with the knowledge that the contrasting domain is constrained in some test domain, constitute the only a priori information about the configuration that is needed. Results of a number of numerical examples are presented which demonstrate the performance of the present inversion scheme. (Copyright (c) 1995 Laboratory of Electromagnetic Research.)