Near-Bit Ultradeep Measurement System for Geosteering and Formation Evaluation

A method to determine a property of a formation traversed by a drilling tool, comprising:

• providing a drilling tool that comprises a near-bit resistivity tool, a deep-reading electromagnetic logging tool, and a drill bit, wherein a distance between near-bit resistivity tool and the drill bit is smaller than a distance between the deep-reading electromagnetic logging tool and the drill bit;
• adjusting a stratigraphic model for the property of the formation by iterative forward modeling using measured responses from the deep-reading electromagnetic logging tool to obtain an adjusted stratigraphic model;
• and
• refining the adjusted stratigraphic model by iterative for forward modeling using measure responses from the near-bit resistivity tool and the gamma-ray detector to obtain a refined stratigraphic model.