• journal_title：Geophysics
• Contributor：Chester J. Weiss ; Gregory A. Newman
• Publisher：Society of Exploration Geophysicists
• Date：2003-
• Format：text/html
• Language：en
• Identifier：10.1190/1.1581044
• journal_abbrev：Geophysics
• issn：0016-8033
• volume：68
• issue：3
• firstpage：922
• section：ELECTRICAL AND ELECTROMAGNETIC METHODS

A practical limitation in the use of generalized 3D forward modeling algorithms for inversion of electromagnetic data is the high computational cost of solving large, ill-conditioned systems of linear equations arising from the discretization of the governing Maxwell equations. To address this problem, a new class of pre-conditioners has recently been proposed which is based on a Helmholtz decomposition of the electric field in the low induction number (LIN) regime. This paper further develops that idea and introduces a LIN preconditioner which can be applied to problems characterized by a fully generalized anisotropic medium. Included are sample calculations demonstrating a reduction by two orders of magnitude in the number of “quasi-minimal residual” iterates and a speedup by a factor of approximately four in the solution time for one forward calculation. Also included are results previously unobtainable by standard Jacobi preconditioning for simulating multicomponent induction sonde response in a horizontal well within a crossbedded formation.