A Fast Inversion Method For Multicomponent Induction Log Data

Summary A new multicomponent induction tool has been developed for detecting resistivity anisotropy of the formation. This new tool comprises of three mutually orthogonal transmitter-receiver coil configurations measuring all components of the magnetic field tensor. To provide the horizontal and vertical resistivities of the formation at well site, we developed a fast, robust, and hands-off inversion method. The method describes the layered formation using equally thick thin layers. A 1-D vertically layered forward modeling code is used to generate the synthetic data. The formation resistivities are updated iteratively by the difference between the synthetic data and the measured data without computing a sensitivity matrix. In a vertical well, the horizontal resistivity is inverted from the Hzz * component first, and then the vertical resistivity is inverted from the Hxx or Hyy component. In a deviated well, we use the same methodology, but we apply a constraint to derive horizontal and vertical resistivities simultaneously. We test the method on synthetic examples and we will show that the algorithm is fast and robust.