Enhanced real-time determination of resistivity anisotropy and dip using multifrequency and multicomponent induction logging

Abstract

Multicomponent induction (MCI) logging is able to provide a wealth of measurements at multiple subarrays and frequencies that can be used to evaluate complex subsurface formations. Real-time and postprocessing inversion methods have been introduced by various researchers for determining formation resistivity anisotropy (horizontal and vertical resistivity or conductivity), dip, and dip azimuth/strike using MCI measurements. The majority of these methods are based on single-frequency information. We have developed an enhanced real-time method and relevant workflow for determining formation resistivity anisotropy, dip, and dip azimuth using multifrequency MCI information. This enhanced method can be used to improve accuracy in formation evaluation applications, such as reservoir identification, hydrocarbon/water saturation calculation, and geologic and structural interpretation. Enhancements over the present single-frequency data processing include: (1) optimal harmonization of multiple single-frequency inverted logs, (2) robust determination of dip and dip azimuth angle for low-resistivity anisotropy ratios, (3) practical data-quality evaluation that takes into account the effects of formation resistivity, anisotropy ratio, and dip parameters, and (4) a new integrated workflow that can be used to determine formation anisotropy, true dip, and dip azimuth by integrating processed relative dip and azimuth and borehole directional logging data. Finally, all of these data process enhancements have been validated with synthetic data and field log data.