Print Email Facebook Twitter Inversion of Electromagnetic Induction Log in Anisotropic Media using an Adjoint Integral Equation Method Title Inversion of Electromagnetic Induction Log in Anisotropic Media using an Adjoint Integral Equation Method Author Saputera, D.H. (University of Bergen) Jakobsen, M. (University of Bergen) Jahani, N. (NORCE Norwegian Research Centre AS) van Dongen, K.W.A. (TU Delft ImPhys/Medical Imaging; TU Delft ImPhys/Van Dongen goup) Alyaev, S. (NORCE Norwegian Research Centre AS) Eikrem, K.S. (NORCE Norwegian Research Centre AS) Date 2024 Abstract Inversion of electromagnetic induction log while drilling provides structural information around borehole for geosteering decision process. Imaging a complex three-dimensional (3D) anisotropic formation is very challenging due to the significant cost of the forward solver. To overcome this challenge, we have developed an inversion algorithm using an adjoint Integral Equation Method for logging while drilling scenarios in anisotropic media with several inexpensive approaches in this study. We use a quasi-Newton method with L-BFGS algorithm and implement a matrix-free adjoint Integral Equation method for efficient update of inverted model parameters. In addition, we propose the use of limited number of iterations for solving the adjoint equation as an approximation to the gradient for a faster computation time. To regularize the inverted models, we adopt the use of multiplicative regularization and weighted L2 total variation. Additionally, we impose priori information in our formulations, such as 2D parameterization and the range of conductivity values. We show a numerical example of logging while drilling inversion on a 2.5D faulted anisotropic formation. Numerical experiments show that our inversion workflow shows a good structural agreement of the inverted model within the sensitive range of the tool. To reference this document use: http://resolver.tudelft.nl/uuid:2622426a-c0f9-4227-99ab-70062eb26e49 DOI https://doi.org/10.3997/2214-4609.2024101259 Embargo date 2024-12-10 Event 85th EAGE Annual Conference & Exhibition 2024, 2024-06-10 → 2024-06-13, NOVA Spektrum Convention Centre, Oslo, Lillestrøm, Norway Bibliographical note Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. Part of collection Institutional Repository Document type conference paper Rights © 2024 D.H. Saputera, M. Jakobsen, N. Jahani, K.W.A. van Dongen, S. Alyaev, K.S. Eikrem Files file embargo until 2024-12-10