ELECTROMAGNETIC INVERSION MODEL REDUCTION

摘要

Various methods for performing inversion of data obtained from a CSEM survey in order to determine resistivity values in a surveyed space are disclosed. A method includes initializing an objective functional dependent measured and modeled electric field data and iteratively minimizing the objective functional to produce an estimated set of expansion coefficients for generating a multi-dimensional record of resistivity values. The set of expansion coefficients is dependent on a resistivity model, which in turn is used to generate an electric field model in the form of a multi-dimensional grid having a number of grid points. Thus, instead of performing the inversion for each point in the grid, the record of resistivity values is generated based on the set of coefficients. The number of coefficients may be at least one decimal order of magnitude less than the number of grid points, and thus the computational effort is reduced.