Patent ID: 8014988
Filing Date: 2011-09-06
Classification: G01V

Abstract:
1. A method for generating a three-dimensional (3D) resistivity model for a subsurface region from one-dimensional (1D) inversion of measured electromagnetic field data from a controlled-source electromagnetic survey of the region, said method comprising: (a) generating an initial resistivity data volume for the subsurface region through 1D inversion of the measured electromagnetic field data said 1D referring to the subsurface region's vertical dimension; (b) solving Maxwell's electromagnetic field equations in three dimensions, assuming the initial resistivity data volume and a selected frequency from the survey source's frequency spectrum, for selected source/receiver locations from the survey, thereby producing calculated electromagnetic field values corresponding to measured survey data; (c) decomposing the measured data to the frequency domain and selecting the component of the data corresponding to the selected frequency; (d) dividing a measured field value from the selected data component by a calculated field value, for different source-receiver pairs along a plurality of source towlines, yielding a set of ratios; (e) assigning an (x,y,z) position to each ratio, in consideration of the locations of the source and receiver pair associated with each ratio, thereby creating a ratio data volume; and (f) multiplying the initial resistivity data volume by a function of the ratio data volume, location-by-location, to generate a 3D resistivity model corresponding to the selected frequency.